/*
 * Copyright (C) 2006 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.widget;

import android.annotation.IdRes;
import android.annotation.NonNull;
import android.annotation.Nullable;
import android.content.Context;
import android.content.Intent;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.os.Trace;
import android.util.AttributeSet;
import android.util.Log;
import android.util.MathUtils;
import android.util.SparseBooleanArray;
import android.view.FocusFinder;
import android.view.KeyEvent;
import android.view.SoundEffectConstants;
import android.view.View;
import android.view.ViewDebug;
import android.view.ViewGroup;
import android.view.ViewHierarchyEncoder;
import android.view.ViewParent;
import android.view.ViewRootImpl;
import android.view.accessibility.AccessibilityNodeInfo;
import android.view.accessibility.AccessibilityNodeInfo.AccessibilityAction;
import android.view.accessibility.AccessibilityNodeInfo.CollectionInfo;
import android.view.accessibility.AccessibilityNodeInfo.CollectionItemInfo;
import android.view.accessibility.AccessibilityNodeProvider;
import android.widget.RemoteViews.RemoteView;

import com.android.internal.R;

import com.google.android.collect.Lists;

import java.util.ArrayList;
import java.util.List;
import java.util.function.Predicate;

/*
 * Implementation Notes:
 *
 * Some terminology:
 *
 *     index    - index of the items that are currently visible
 *     position - index of the items in the cursor
 */


Displays a vertically-scrollable collection of views, where each view is positioned immediatelybelow the previous view in the list. For a more modern, flexible, and performant approach to displaying lists, use RecyclerView.
To display a list, you can include a list view in your layout XML file:
<ListView
     android:id="@+id/list_view"
     android:layout_width="match_parent"
     android:layout_height="match_parent" />
A list view is an 
adapter view that does not know the details, such as type and contents, of the views it contains. Instead list view requests views on demand from a ListAdapter as needed, such as to display new views as the user scrolls up or down.
In order to display items in the list, call setAdapter(ListAdapter adapter) to associate an adapter with the list. For a simple example, see the discussion of filling an adapter view with text in the 
Layouts guide.
To display a more custom view for each item in your dataset, implement a ListAdapter. For example, extend BaseAdapter and create and configure the view for each data item in getView(...):
 
private class MyAdapter extends BaseAdapter {
     // override other abstract methods here
     @Override
     public View getView(int position, View convertView, ViewGroup container) {
         if (convertView == null) {
             convertView = getLayoutInflater().inflate(R.layout.list_item, container, false);
         }
         ((TextView) convertView.findViewById(android.R.id.text1))
                 .setText(getItem(position));
         return convertView;
     }
 }
ListView attempts to reuse view objects in order to improve performance and avoid a lag in response to user scrolls. To take advantage of this feature, check if the convertView provided to getView(...) is null before creating or inflating a new view object. See 
Making ListView Scrolling Smooth for more ways to ensure a smooth user experience.
For a more complete example of creating a custom adapter, see the

    Custom Choice List sample app.
To specify an action when a user clicks or taps on a single list item, see

    Handling click events.
To learn how to populate a list view with a CursorAdapter, see the discussion of filling an
adapter view with text in the

Layouts guide.
See 
    Using a Loader
to learn how to avoid blocking the main thread when using a cursor.
Note, many examples use ListActivity or ListFragment to display a list view. Instead, favor the more flexible approach when writing your own app: use a more generic Activity subclass or Fragment subclass and add a list view to the layout or view hierarchy directly. This approach gives you more direct control of the list view and adapter.
@attr
ref android.R.styleable#ListView_entries
@attr
ref android.R.styleable#ListView_divider
@attr
ref android.R.styleable#ListView_dividerHeight
@attr
ref android.R.styleable#ListView_headerDividersEnabled
@attr
ref android.R.styleable#ListView_footerDividersEnabled/**
 * <p>Displays a vertically-scrollable collection of views, where each view is positioned
 * immediatelybelow the previous view in the list.  For a more modern, flexible, and performant
 * approach to displaying lists, use {@link android.support.v7.widget.RecyclerView}.</p>
 *
 * <p>To display a list, you can include a list view in your layout XML file:</p>
 *
 * <pre>&lt;ListView
 *      android:id="@+id/list_view"
 *      android:layout_width="match_parent"
 *      android:layout_height="match_parent" /&gt;</pre>
 *
 * <p>A list view is an <a href="{@docRoot}guide/topics/ui/declaring-layout.html#AdapterViews">
 * adapter view</a> that does not know the details, such as type and contents, of the views it
 * contains. Instead list view requests views on demand from a {@link ListAdapter} as needed,
 * such as to display new views as the user scrolls up or down.</p>
 *
 * <p>In order to display items in the list, call {@link #setAdapter(ListAdapter adapter)}
 * to associate an adapter with the list.  For a simple example, see the discussion of filling an
 * adapter view with text in the
 * <a href="{@docRoot}guide/topics/ui/declaring-layout.html#FillingTheLayout">
 * Layouts</a> guide.</p>
 *
 * <p>To display a more custom view for each item in your dataset, implement a ListAdapter.
 * For example, extend {@link BaseAdapter} and create and configure the view for each data item in
 * {@code getView(...)}:</p>
 *
 *  <pre>private class MyAdapter extends BaseAdapter {
 *
 *      // override other abstract methods here
 *
 *      &#64;Override
 *      public View getView(int position, View convertView, ViewGroup container) {
 *          if (convertView == null) {
 *              convertView = getLayoutInflater().inflate(R.layout.list_item, container, false);
 *          }
 *
 *          ((TextView) convertView.findViewById(android.R.id.text1))
 *                  .setText(getItem(position));
 *          return convertView;
 *      }
 *  }</pre>
 *
 * <p class="note">ListView attempts to reuse view objects in order to improve performance and
 * avoid a lag in response to user scrolls.  To take advantage of this feature, check if the
 * {@code convertView} provided to {@code getView(...)} is null before creating or inflating a new
 * view object.  See
 * <a href="{@docRoot}training/improving-layouts/smooth-scrolling.html">
 * Making ListView Scrolling Smooth</a> for more ways to ensure a smooth user experience.</p>
 *
 * <p>For a more complete example of creating a custom adapter, see the
 * <a href="{@docRoot}samples/CustomChoiceList/index.html">
 *     Custom Choice List</a> sample app.</p>
 *
 * <p>To specify an action when a user clicks or taps on a single list item, see
 * <a href="{@docRoot}guide/topics/ui/declaring-layout.html#HandlingUserSelections">
 *     Handling click events</a>.</p>
 *
 * <p>To learn how to populate a list view with a CursorAdapter, see the discussion of filling an
 * adapter view with text in the
 * <a href="{@docRoot}guide/topics/ui/declaring-layout.html#FillingTheLayout">
 * Layouts</a> guide.
 * See <a href="{@docRoot}guide/topics/ui/layout/listview.html">
 *     Using a Loader</a>
 * to learn how to avoid blocking the main thread when using a cursor.</p>
 *
 * <p class="note">Note, many examples use {@link android.app.ListActivity ListActivity}
 * or {@link android.app.ListFragment ListFragment}
 * to display a list view. Instead, favor the more flexible approach when writing your own app:
 * use a more generic Activity subclass or Fragment subclass and add a list view to the layout
 * or view hierarchy directly.  This approach gives you more direct control of the
 * list view and adapter.</p>
 *
 * @attr ref android.R.styleable#ListView_entries
 * @attr ref android.R.styleable#ListView_divider
 * @attr ref android.R.styleable#ListView_dividerHeight
 * @attr ref android.R.styleable#ListView_headerDividersEnabled
 * @attr ref android.R.styleable#ListView_footerDividersEnabled
 */
@RemoteView
public class ListView extends AbsListView {
    static final String TAG = "ListView";

    
Used to indicate a no preference for a position type.
/**
     * Used to indicate a no preference for a position type.
     */
    static final int NO_POSITION = -1;

    
When arrow scrolling, ListView will never scroll more than this factor
times the height of the list.
/**
     * When arrow scrolling, ListView will never scroll more than this factor
     * times the height of the list.
     */
    private static final float MAX_SCROLL_FACTOR = 0.33f;

    
When arrow scrolling, need a certain amount of pixels to preview next
items.  This is usually the fading edge, but if that is small enough,
we want to make sure we preview at least this many pixels.
/**
     * When arrow scrolling, need a certain amount of pixels to preview next
     * items.  This is usually the fading edge, but if that is small enough,
     * we want to make sure we preview at least this many pixels.
     */
    private static final int MIN_SCROLL_PREVIEW_PIXELS = 2;

    
A class that represents a fixed view in a list, for example a header at the top
or a footer at the bottom.
/**
     * A class that represents a fixed view in a list, for example a header at the top
     * or a footer at the bottom.
     */
    public class FixedViewInfo {
        
The view to add to the list /** The view to add to the list */
        public View view;
        
The data backing the view. This is returned from Adapter.getItem(int). /** The data backing the view. This is returned from {@link ListAdapter#getItem(int)}. */
        public Object data;
        
true if the fixed view should be selectable in the list /** <code>true</code> if the fixed view should be selectable in the list */
        public boolean isSelectable;
    }

    ArrayList<FixedViewInfo> mHeaderViewInfos = Lists.newArrayList();
    ArrayList<FixedViewInfo> mFooterViewInfos = Lists.newArrayList();

    Drawable mDivider;
    int mDividerHeight;

    Drawable mOverScrollHeader;
    Drawable mOverScrollFooter;

    private boolean mIsCacheColorOpaque;
    private boolean mDividerIsOpaque;

    private boolean mHeaderDividersEnabled;
    private boolean mFooterDividersEnabled;

    private boolean mAreAllItemsSelectable = true;

    private boolean mItemsCanFocus = false;

    // used for temporary calculations.
    private final Rect mTempRect = new Rect();
    private Paint mDividerPaint;

    // the single allocated result per list view; kinda cheesey but avoids
    // allocating these thingies too often.
    private final ArrowScrollFocusResult mArrowScrollFocusResult = new ArrowScrollFocusResult();

    // Keeps focused children visible through resizes
    private FocusSelector mFocusSelector;

    public ListView(Context context) {
        this(context, null);
    }

    public ListView(Context context, AttributeSet attrs) {
        this(context, attrs, R.attr.listViewStyle);
    }

    public ListView(Context context, AttributeSet attrs, int defStyleAttr) {
        this(context, attrs, defStyleAttr, 0);
    }

    public ListView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);

        final TypedArray a = context.obtainStyledAttributes(
                attrs, R.styleable.ListView, defStyleAttr, defStyleRes);

        final CharSequence[] entries = a.getTextArray(R.styleable.ListView_entries);
        if (entries != null) {
            setAdapter(new ArrayAdapter<>(context, R.layout.simple_list_item_1, entries));
        }

        final Drawable d = a.getDrawable(R.styleable.ListView_divider);
        if (d != null) {
            // Use an implicit divider height which may be explicitly
            // overridden by android:dividerHeight further down.
            setDivider(d);
        }

        final Drawable osHeader = a.getDrawable(R.styleable.ListView_overScrollHeader);
        if (osHeader != null) {
            setOverscrollHeader(osHeader);
        }

        final Drawable osFooter = a.getDrawable(R.styleable.ListView_overScrollFooter);
        if (osFooter != null) {
            setOverscrollFooter(osFooter);
        }

        // Use an explicit divider height, if specified.
        if (a.hasValueOrEmpty(R.styleable.ListView_dividerHeight)) {
            final int dividerHeight = a.getDimensionPixelSize(
                    R.styleable.ListView_dividerHeight, 0);
            if (dividerHeight != 0) {
                setDividerHeight(dividerHeight);
            }
        }

        mHeaderDividersEnabled = a.getBoolean(R.styleable.ListView_headerDividersEnabled, true);
        mFooterDividersEnabled = a.getBoolean(R.styleable.ListView_footerDividersEnabled, true);

        a.recycle();
    }

    
Returns:
The maximum amount a list view will scroll in response to
  an arrow event./**
     * @return The maximum amount a list view will scroll in response to
     *   an arrow event.
     */
    public int getMaxScrollAmount() {
        return (int) (MAX_SCROLL_FACTOR * (mBottom - mTop));
    }

    
Make sure views are touching the top or bottom edge, as appropriate for
our gravity
/**
     * Make sure views are touching the top or bottom edge, as appropriate for
     * our gravity
     */
    private void adjustViewsUpOrDown() {
        final int childCount = getChildCount();
        int delta;

        if (childCount > 0) {
            View child;

            if (!mStackFromBottom) {
                // Uh-oh -- we came up short. Slide all views up to make them
                // align with the top
                child = getChildAt(0);
                delta = child.getTop() - mListPadding.top;
                if (mFirstPosition != 0) {
                    // It's OK to have some space above the first item if it is
                    // part of the vertical spacing
                    delta -= mDividerHeight;
                }
                if (delta < 0) {
                    // We only are looking to see if we are too low, not too high
                    delta = 0;
                }
            } else {
                // we are too high, slide all views down to align with bottom
                child = getChildAt(childCount - 1);
                delta = child.getBottom() - (getHeight() - mListPadding.bottom);

                if (mFirstPosition + childCount < mItemCount) {
                    // It's OK to have some space below the last item if it is
                    // part of the vertical spacing
                    delta += mDividerHeight;
                }

                if (delta > 0) {
                    delta = 0;
                }
            }

            if (delta != 0) {
                offsetChildrenTopAndBottom(-delta);
            }
        }
    }

    
Add a fixed view to appear at the top of the list. If this method is
called more than once, the views will appear in the order they were
added. Views added using this call can take focus if they want.
 Note: When first introduced, this method could only be called before setting the adapter with setAdapter(ListAdapter). Starting with VERSION_CODES.KITKAT, this method may be called at any time. If the ListView's adapter does not extend HeaderViewListAdapter, it will be wrapped with a supporting instance of WrapperListAdapter. 
Params:
v – The view to add.
data – Data to associate with this view
isSelectable – whether the item is selectable/**
     * Add a fixed view to appear at the top of the list. If this method is
     * called more than once, the views will appear in the order they were
     * added. Views added using this call can take focus if they want.
     * <p>
     * Note: When first introduced, this method could only be called before
     * setting the adapter with {@link #setAdapter(ListAdapter)}. Starting with
     * {@link android.os.Build.VERSION_CODES#KITKAT}, this method may be
     * called at any time. If the ListView's adapter does not extend
     * {@link HeaderViewListAdapter}, it will be wrapped with a supporting
     * instance of {@link WrapperListAdapter}.
     *
     * @param v The view to add.
     * @param data Data to associate with this view
     * @param isSelectable whether the item is selectable
     */
    public void addHeaderView(View v, Object data, boolean isSelectable) {
        if (v.getParent() != null && v.getParent() != this) {
            if (Log.isLoggable(TAG, Log.WARN)) {
                Log.w(TAG, "The specified child already has a parent. "
                           + "You must call removeView() on the child's parent first.");
            }
        }
        final FixedViewInfo info = new FixedViewInfo();
        info.view = v;
        info.data = data;
        info.isSelectable = isSelectable;
        mHeaderViewInfos.add(info);
        mAreAllItemsSelectable &= isSelectable;

        // Wrap the adapter if it wasn't already wrapped.
        if (mAdapter != null) {
            if (!(mAdapter instanceof HeaderViewListAdapter)) {
                wrapHeaderListAdapterInternal();
            }

            // In the case of re-adding a header view, or adding one later on,
            // we need to notify the observer.
            if (mDataSetObserver != null) {
                mDataSetObserver.onChanged();
            }
        }
    }

    
Add a fixed view to appear at the top of the list. If addHeaderView is
called more than once, the views will appear in the order they were
added. Views added using this call can take focus if they want.
 Note: When first introduced, this method could only be called before setting the adapter with setAdapter(ListAdapter). Starting with VERSION_CODES.KITKAT, this method may be called at any time. If the ListView's adapter does not extend HeaderViewListAdapter, it will be wrapped with a supporting instance of WrapperListAdapter. 
Params:
v – The view to add./**
     * Add a fixed view to appear at the top of the list. If addHeaderView is
     * called more than once, the views will appear in the order they were
     * added. Views added using this call can take focus if they want.
     * <p>
     * Note: When first introduced, this method could only be called before
     * setting the adapter with {@link #setAdapter(ListAdapter)}. Starting with
     * {@link android.os.Build.VERSION_CODES#KITKAT}, this method may be
     * called at any time. If the ListView's adapter does not extend
     * {@link HeaderViewListAdapter}, it will be wrapped with a supporting
     * instance of {@link WrapperListAdapter}.
     *
     * @param v The view to add.
     */
    public void addHeaderView(View v) {
        addHeaderView(v, null, true);
    }

    @Override
    public int getHeaderViewsCount() {
        return mHeaderViewInfos.size();
    }

    
Removes a previously-added header view.
Params:
v – The view to remove
Returns:
true if the view was removed, false if the view was not a header
        view/**
     * Removes a previously-added header view.
     *
     * @param v The view to remove
     * @return true if the view was removed, false if the view was not a header
     *         view
     */
    public boolean removeHeaderView(View v) {
        if (mHeaderViewInfos.size() > 0) {
            boolean result = false;
            if (mAdapter != null && ((HeaderViewListAdapter) mAdapter).removeHeader(v)) {
                if (mDataSetObserver != null) {
                    mDataSetObserver.onChanged();
                }
                result = true;
            }
            removeFixedViewInfo(v, mHeaderViewInfos);
            return result;
        }
        return false;
    }

    private void removeFixedViewInfo(View v, ArrayList<FixedViewInfo> where) {
        int len = where.size();
        for (int i = 0; i < len; ++i) {
            FixedViewInfo info = where.get(i);
            if (info.view == v) {
                where.remove(i);
                break;
            }
        }
    }

    
Add a fixed view to appear at the bottom of the list. If addFooterView is
called more than once, the views will appear in the order they were
added. Views added using this call can take focus if they want.
 Note: When first introduced, this method could only be called before setting the adapter with setAdapter(ListAdapter). Starting with VERSION_CODES.KITKAT, this method may be called at any time. If the ListView's adapter does not extend HeaderViewListAdapter, it will be wrapped with a supporting instance of WrapperListAdapter. 
Params:
v – The view to add.
data – Data to associate with this view
isSelectable – true if the footer view can be selected/**
     * Add a fixed view to appear at the bottom of the list. If addFooterView is
     * called more than once, the views will appear in the order they were
     * added. Views added using this call can take focus if they want.
     * <p>
     * Note: When first introduced, this method could only be called before
     * setting the adapter with {@link #setAdapter(ListAdapter)}. Starting with
     * {@link android.os.Build.VERSION_CODES#KITKAT}, this method may be
     * called at any time. If the ListView's adapter does not extend
     * {@link HeaderViewListAdapter}, it will be wrapped with a supporting
     * instance of {@link WrapperListAdapter}.
     *
     * @param v The view to add.
     * @param data Data to associate with this view
     * @param isSelectable true if the footer view can be selected
     */
    public void addFooterView(View v, Object data, boolean isSelectable) {
        if (v.getParent() != null && v.getParent() != this) {
            if (Log.isLoggable(TAG, Log.WARN)) {
                Log.w(TAG, "The specified child already has a parent. "
                           + "You must call removeView() on the child's parent first.");
            }
        }

        final FixedViewInfo info = new FixedViewInfo();
        info.view = v;
        info.data = data;
        info.isSelectable = isSelectable;
        mFooterViewInfos.add(info);
        mAreAllItemsSelectable &= isSelectable;

        // Wrap the adapter if it wasn't already wrapped.
        if (mAdapter != null) {
            if (!(mAdapter instanceof HeaderViewListAdapter)) {
                wrapHeaderListAdapterInternal();
            }

            // In the case of re-adding a footer view, or adding one later on,
            // we need to notify the observer.
            if (mDataSetObserver != null) {
                mDataSetObserver.onChanged();
            }
        }
    }

    
Add a fixed view to appear at the bottom of the list. If addFooterView is
called more than once, the views will appear in the order they were
added. Views added using this call can take focus if they want.
 Note: When first introduced, this method could only be called before setting the adapter with setAdapter(ListAdapter). Starting with VERSION_CODES.KITKAT, this method may be called at any time. If the ListView's adapter does not extend HeaderViewListAdapter, it will be wrapped with a supporting instance of WrapperListAdapter. 
Params:
v – The view to add./**
     * Add a fixed view to appear at the bottom of the list. If addFooterView is
     * called more than once, the views will appear in the order they were
     * added. Views added using this call can take focus if they want.
     * <p>
     * Note: When first introduced, this method could only be called before
     * setting the adapter with {@link #setAdapter(ListAdapter)}. Starting with
     * {@link android.os.Build.VERSION_CODES#KITKAT}, this method may be
     * called at any time. If the ListView's adapter does not extend
     * {@link HeaderViewListAdapter}, it will be wrapped with a supporting
     * instance of {@link WrapperListAdapter}.
     *
     * @param v The view to add.
     */
    public void addFooterView(View v) {
        addFooterView(v, null, true);
    }

    @Override
    public int getFooterViewsCount() {
        return mFooterViewInfos.size();
    }

    
Removes a previously-added footer view.
Params:
v – The view to remove
Returns:

true if the view was removed, false if the view was not a footer view/**
     * Removes a previously-added footer view.
     *
     * @param v The view to remove
     * @return
     * true if the view was removed, false if the view was not a footer view
     */
    public boolean removeFooterView(View v) {
        if (mFooterViewInfos.size() > 0) {
            boolean result = false;
            if (mAdapter != null && ((HeaderViewListAdapter) mAdapter).removeFooter(v)) {
                if (mDataSetObserver != null) {
                    mDataSetObserver.onChanged();
                }
                result = true;
            }
            removeFixedViewInfo(v, mFooterViewInfos);
            return result;
        }
        return false;
    }

    
Returns the adapter currently in use in this ListView. The returned adapter might not be the same adapter passed to setAdapter(ListAdapter) but might be a WrapperListAdapter. 
See Also:
setAdapter(ListAdapter)
Returns:
The adapter currently used to display data in this ListView./**
     * Returns the adapter currently in use in this ListView. The returned adapter
     * might not be the same adapter passed to {@link #setAdapter(ListAdapter)} but
     * might be a {@link WrapperListAdapter}.
     *
     * @return The adapter currently used to display data in this ListView.
     *
     * @see #setAdapter(ListAdapter)
     */
    @Override
    public ListAdapter getAdapter() {
        return mAdapter;
    }

    
Sets up this AbsListView to use a remote views adapter which connects to a RemoteViewsService
through the specified intent.
Params:
intent – the intent used to identify the RemoteViewsService for the adapter to connect to./**
     * Sets up this AbsListView to use a remote views adapter which connects to a RemoteViewsService
     * through the specified intent.
     * @param intent the intent used to identify the RemoteViewsService for the adapter to connect to.
     */
    @android.view.RemotableViewMethod(asyncImpl="setRemoteViewsAdapterAsync")
    public void setRemoteViewsAdapter(Intent intent) {
        super.setRemoteViewsAdapter(intent);
    }

    
Sets the data behind this ListView. The adapter passed to this method may be wrapped by a WrapperListAdapter, depending on the ListView features currently in use. For instance, adding headers and/or footers will cause the adapter to be wrapped. 
Params:
adapter – The ListAdapter which is responsible for maintaining the
       data backing this list and for producing a view to represent an
       item in that data set.
See Also:
getAdapter()/**
     * Sets the data behind this ListView.
     *
     * The adapter passed to this method may be wrapped by a {@link WrapperListAdapter},
     * depending on the ListView features currently in use. For instance, adding
     * headers and/or footers will cause the adapter to be wrapped.
     *
     * @param adapter The ListAdapter which is responsible for maintaining the
     *        data backing this list and for producing a view to represent an
     *        item in that data set.
     *
     * @see #getAdapter()
     */
    @Override
    public void setAdapter(ListAdapter adapter) {
        if (mAdapter != null && mDataSetObserver != null) {
            mAdapter.unregisterDataSetObserver(mDataSetObserver);
        }

        resetList();
        mRecycler.clear();

        if (mHeaderViewInfos.size() > 0|| mFooterViewInfos.size() > 0) {
            mAdapter = wrapHeaderListAdapterInternal(mHeaderViewInfos, mFooterViewInfos, adapter);
        } else {
            mAdapter = adapter;
        }

        mOldSelectedPosition = INVALID_POSITION;
        mOldSelectedRowId = INVALID_ROW_ID;

        // AbsListView#setAdapter will update choice mode states.
        super.setAdapter(adapter);

        if (mAdapter != null) {
            mAreAllItemsSelectable = mAdapter.areAllItemsEnabled();
            mOldItemCount = mItemCount;
            mItemCount = mAdapter.getCount();
            checkFocus();

            mDataSetObserver = new AdapterDataSetObserver();
            mAdapter.registerDataSetObserver(mDataSetObserver);

            mRecycler.setViewTypeCount(mAdapter.getViewTypeCount());

            int position;
            if (mStackFromBottom) {
                position = lookForSelectablePosition(mItemCount - 1, false);
            } else {
                position = lookForSelectablePosition(0, true);
            }
            setSelectedPositionInt(position);
            setNextSelectedPositionInt(position);

            if (mItemCount == 0) {
                // Nothing selected
                checkSelectionChanged();
            }
        } else {
            mAreAllItemsSelectable = true;
            checkFocus();
            // Nothing selected
            checkSelectionChanged();
        }

        requestLayout();
    }

    
The list is empty. Clear everything out.
/**
     * The list is empty. Clear everything out.
     */
    @Override
    void resetList() {
        // The parent's resetList() will remove all views from the layout so we need to
        // cleanup the state of our footers and headers
        clearRecycledState(mHeaderViewInfos);
        clearRecycledState(mFooterViewInfos);

        super.resetList();

        mLayoutMode = LAYOUT_NORMAL;
    }

    private void clearRecycledState(ArrayList<FixedViewInfo> infos) {
        if (infos != null) {
            final int count = infos.size();

            for (int i = 0; i < count; i++) {
                final View child = infos.get(i).view;
                final ViewGroup.LayoutParams params = child.getLayoutParams();
                if (checkLayoutParams(params)) {
                    ((LayoutParams) params).recycledHeaderFooter = false;
                }
            }
        }
    }

    
Returns:
Whether the list needs to show the top fading edge/**
     * @return Whether the list needs to show the top fading edge
     */
    private boolean showingTopFadingEdge() {
        final int listTop = mScrollY + mListPadding.top;
        return (mFirstPosition > 0) || (getChildAt(0).getTop() > listTop);
    }

    
Returns:
Whether the list needs to show the bottom fading edge/**
     * @return Whether the list needs to show the bottom fading edge
     */
    private boolean showingBottomFadingEdge() {
        final int childCount = getChildCount();
        final int bottomOfBottomChild = getChildAt(childCount - 1).getBottom();
        final int lastVisiblePosition = mFirstPosition + childCount - 1;

        final int listBottom = mScrollY + getHeight() - mListPadding.bottom;

        return (lastVisiblePosition < mItemCount - 1)
                         || (bottomOfBottomChild < listBottom);
    }


    @Override
    public boolean requestChildRectangleOnScreen(View child, Rect rect, boolean immediate) {

        int rectTopWithinChild = rect.top;

        // offset so rect is in coordinates of the this view
        rect.offset(child.getLeft(), child.getTop());
        rect.offset(-child.getScrollX(), -child.getScrollY());

        final int height = getHeight();
        int listUnfadedTop = getScrollY();
        int listUnfadedBottom = listUnfadedTop + height;
        final int fadingEdge = getVerticalFadingEdgeLength();

        if (showingTopFadingEdge()) {
            // leave room for top fading edge as long as rect isn't at very top
            if ((mSelectedPosition > 0) || (rectTopWithinChild > fadingEdge)) {
                listUnfadedTop += fadingEdge;
            }
        }

        int childCount = getChildCount();
        int bottomOfBottomChild = getChildAt(childCount - 1).getBottom();

        if (showingBottomFadingEdge()) {
            // leave room for bottom fading edge as long as rect isn't at very bottom
            if ((mSelectedPosition < mItemCount - 1)
                    || (rect.bottom < (bottomOfBottomChild - fadingEdge))) {
                listUnfadedBottom -= fadingEdge;
            }
        }

        int scrollYDelta = 0;

        if (rect.bottom > listUnfadedBottom && rect.top > listUnfadedTop) {
            // need to MOVE DOWN to get it in view: move down just enough so
            // that the entire rectangle is in view (or at least the first
            // screen size chunk).

            if (rect.height() > height) {
                // just enough to get screen size chunk on
                scrollYDelta += (rect.top - listUnfadedTop);
            } else {
                // get entire rect at bottom of screen
                scrollYDelta += (rect.bottom - listUnfadedBottom);
            }

            // make sure we aren't scrolling beyond the end of our children
            int distanceToBottom = bottomOfBottomChild - listUnfadedBottom;
            scrollYDelta = Math.min(scrollYDelta, distanceToBottom);
        } else if (rect.top < listUnfadedTop && rect.bottom < listUnfadedBottom) {
            // need to MOVE UP to get it in view: move up just enough so that
            // entire rectangle is in view (or at least the first screen
            // size chunk of it).

            if (rect.height() > height) {
                // screen size chunk
                scrollYDelta -= (listUnfadedBottom - rect.bottom);
            } else {
                // entire rect at top
                scrollYDelta -= (listUnfadedTop - rect.top);
            }

            // make sure we aren't scrolling any further than the top our children
            int top = getChildAt(0).getTop();
            int deltaToTop = top - listUnfadedTop;
            scrollYDelta = Math.max(scrollYDelta, deltaToTop);
        }

        final boolean scroll = scrollYDelta != 0;
        if (scroll) {
            scrollListItemsBy(-scrollYDelta);
            positionSelector(INVALID_POSITION, child);
            mSelectedTop = child.getTop();
            invalidate();
        }
        return scroll;
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    void fillGap(boolean down) {
        final int count = getChildCount();
        if (down) {
            int paddingTop = 0;
            if ((mGroupFlags & CLIP_TO_PADDING_MASK) == CLIP_TO_PADDING_MASK) {
                paddingTop = getListPaddingTop();
            }
            final int startOffset = count > 0 ? getChildAt(count - 1).getBottom() + mDividerHeight :
                    paddingTop;
            fillDown(mFirstPosition + count, startOffset);
            correctTooHigh(getChildCount());
        } else {
            int paddingBottom = 0;
            if ((mGroupFlags & CLIP_TO_PADDING_MASK) == CLIP_TO_PADDING_MASK) {
                paddingBottom = getListPaddingBottom();
            }
            final int startOffset = count > 0 ? getChildAt(0).getTop() - mDividerHeight :
                    getHeight() - paddingBottom;
            fillUp(mFirstPosition - 1, startOffset);
            correctTooLow(getChildCount());
        }
    }

    
Fills the list from pos down to the end of the list view.
Params:
pos – The first position to put in the list
nextTop – The location where the top of the item associated with pos
       should be drawn
Returns:
The view that is currently selected, if it happens to be in the
        range that we draw./**
     * Fills the list from pos down to the end of the list view.
     *
     * @param pos The first position to put in the list
     *
     * @param nextTop The location where the top of the item associated with pos
     *        should be drawn
     *
     * @return The view that is currently selected, if it happens to be in the
     *         range that we draw.
     */
    private View fillDown(int pos, int nextTop) {
        View selectedView = null;

        int end = (mBottom - mTop);
        if ((mGroupFlags & CLIP_TO_PADDING_MASK) == CLIP_TO_PADDING_MASK) {
            end -= mListPadding.bottom;
        }

        while (nextTop < end && pos < mItemCount) {
            // is this the selected item?
            boolean selected = pos == mSelectedPosition;
            View child = makeAndAddView(pos, nextTop, true, mListPadding.left, selected);

            nextTop = child.getBottom() + mDividerHeight;
            if (selected) {
                selectedView = child;
            }
            pos++;
        }

        setVisibleRangeHint(mFirstPosition, mFirstPosition + getChildCount() - 1);
        return selectedView;
    }

    
Fills the list from pos up to the top of the list view.
Params:
pos – The first position to put in the list
nextBottom – The location where the bottom of the item associated
       with pos should be drawn
Returns:
The view that is currently selected/**
     * Fills the list from pos up to the top of the list view.
     *
     * @param pos The first position to put in the list
     *
     * @param nextBottom The location where the bottom of the item associated
     *        with pos should be drawn
     *
     * @return The view that is currently selected
     */
    private View fillUp(int pos, int nextBottom) {
        View selectedView = null;

        int end = 0;
        if ((mGroupFlags & CLIP_TO_PADDING_MASK) == CLIP_TO_PADDING_MASK) {
            end = mListPadding.top;
        }

        while (nextBottom > end && pos >= 0) {
            // is this the selected item?
            boolean selected = pos == mSelectedPosition;
            View child = makeAndAddView(pos, nextBottom, false, mListPadding.left, selected);
            nextBottom = child.getTop() - mDividerHeight;
            if (selected) {
                selectedView = child;
            }
            pos--;
        }

        mFirstPosition = pos + 1;
        setVisibleRangeHint(mFirstPosition, mFirstPosition + getChildCount() - 1);
        return selectedView;
    }

    
Fills the list from top to bottom, starting with mFirstPosition
Params:
nextTop – The location where the top of the first item should be
       drawn
Returns:
The view that is currently selected/**
     * Fills the list from top to bottom, starting with mFirstPosition
     *
     * @param nextTop The location where the top of the first item should be
     *        drawn
     *
     * @return The view that is currently selected
     */
    private View fillFromTop(int nextTop) {
        mFirstPosition = Math.min(mFirstPosition, mSelectedPosition);
        mFirstPosition = Math.min(mFirstPosition, mItemCount - 1);
        if (mFirstPosition < 0) {
            mFirstPosition = 0;
        }
        return fillDown(mFirstPosition, nextTop);
    }


    
Put mSelectedPosition in the middle of the screen and then build up and
down from there. This method forces mSelectedPosition to the center.
Params:
childrenTop – Top of the area in which children can be drawn, as
       measured in pixels
childrenBottom – Bottom of the area in which children can be drawn,
       as measured in pixels
Returns:
Currently selected view/**
     * Put mSelectedPosition in the middle of the screen and then build up and
     * down from there. This method forces mSelectedPosition to the center.
     *
     * @param childrenTop Top of the area in which children can be drawn, as
     *        measured in pixels
     * @param childrenBottom Bottom of the area in which children can be drawn,
     *        as measured in pixels
     * @return Currently selected view
     */
    private View fillFromMiddle(int childrenTop, int childrenBottom) {
        int height = childrenBottom - childrenTop;

        int position = reconcileSelectedPosition();

        View sel = makeAndAddView(position, childrenTop, true,
                mListPadding.left, true);
        mFirstPosition = position;

        int selHeight = sel.getMeasuredHeight();
        if (selHeight <= height) {
            sel.offsetTopAndBottom((height - selHeight) / 2);
        }

        fillAboveAndBelow(sel, position);

        if (!mStackFromBottom) {
            correctTooHigh(getChildCount());
        } else {
            correctTooLow(getChildCount());
        }

        return sel;
    }

    
Once the selected view as been placed, fill up the visible area above and
below it.
Params:
sel – The selected view
position – The position corresponding to sel/**
     * Once the selected view as been placed, fill up the visible area above and
     * below it.
     *
     * @param sel The selected view
     * @param position The position corresponding to sel
     */
    private void fillAboveAndBelow(View sel, int position) {
        final int dividerHeight = mDividerHeight;
        if (!mStackFromBottom) {
            fillUp(position - 1, sel.getTop() - dividerHeight);
            adjustViewsUpOrDown();
            fillDown(position + 1, sel.getBottom() + dividerHeight);
        } else {
            fillDown(position + 1, sel.getBottom() + dividerHeight);
            adjustViewsUpOrDown();
            fillUp(position - 1, sel.getTop() - dividerHeight);
        }
    }


    
Fills the grid based on positioning the new selection at a specific
location. The selection may be moved so that it does not intersect the
faded edges. The grid is then filled upwards and downwards from there.
Params:
selectedTop – Where the selected item should be
childrenTop – Where to start drawing children
childrenBottom – Last pixel where children can be drawn
Returns:
The view that currently has selection/**
     * Fills the grid based on positioning the new selection at a specific
     * location. The selection may be moved so that it does not intersect the
     * faded edges. The grid is then filled upwards and downwards from there.
     *
     * @param selectedTop Where the selected item should be
     * @param childrenTop Where to start drawing children
     * @param childrenBottom Last pixel where children can be drawn
     * @return The view that currently has selection
     */
    private View fillFromSelection(int selectedTop, int childrenTop, int childrenBottom) {
        int fadingEdgeLength = getVerticalFadingEdgeLength();
        final int selectedPosition = mSelectedPosition;

        View sel;

        final int topSelectionPixel = getTopSelectionPixel(childrenTop, fadingEdgeLength,
                selectedPosition);
        final int bottomSelectionPixel = getBottomSelectionPixel(childrenBottom, fadingEdgeLength,
                selectedPosition);

        sel = makeAndAddView(selectedPosition, selectedTop, true, mListPadding.left, true);


        // Some of the newly selected item extends below the bottom of the list
        if (sel.getBottom() > bottomSelectionPixel) {
            // Find space available above the selection into which we can scroll
            // upwards
            final int spaceAbove = sel.getTop() - topSelectionPixel;

            // Find space required to bring the bottom of the selected item
            // fully into view
            final int spaceBelow = sel.getBottom() - bottomSelectionPixel;
            final int offset = Math.min(spaceAbove, spaceBelow);

            // Now offset the selected item to get it into view
            sel.offsetTopAndBottom(-offset);
        } else if (sel.getTop() < topSelectionPixel) {
            // Find space required to bring the top of the selected item fully
            // into view
            final int spaceAbove = topSelectionPixel - sel.getTop();

            // Find space available below the selection into which we can scroll
            // downwards
            final int spaceBelow = bottomSelectionPixel - sel.getBottom();
            final int offset = Math.min(spaceAbove, spaceBelow);

            // Offset the selected item to get it into view
            sel.offsetTopAndBottom(offset);
        }

        // Fill in views above and below
        fillAboveAndBelow(sel, selectedPosition);

        if (!mStackFromBottom) {
            correctTooHigh(getChildCount());
        } else {
            correctTooLow(getChildCount());
        }

        return sel;
    }

    
Calculate the bottom-most pixel we can draw the selection into
Params:
childrenBottom – Bottom pixel were children can be drawn
fadingEdgeLength – Length of the fading edge in pixels, if present
selectedPosition – The position that will be selected
Returns:
The bottom-most pixel we can draw the selection into/**
     * Calculate the bottom-most pixel we can draw the selection into
     *
     * @param childrenBottom Bottom pixel were children can be drawn
     * @param fadingEdgeLength Length of the fading edge in pixels, if present
     * @param selectedPosition The position that will be selected
     * @return The bottom-most pixel we can draw the selection into
     */
    private int getBottomSelectionPixel(int childrenBottom, int fadingEdgeLength,
            int selectedPosition) {
        int bottomSelectionPixel = childrenBottom;
        if (selectedPosition != mItemCount - 1) {
            bottomSelectionPixel -= fadingEdgeLength;
        }
        return bottomSelectionPixel;
    }

    
Calculate the top-most pixel we can draw the selection into
Params:
childrenTop – Top pixel were children can be drawn
fadingEdgeLength – Length of the fading edge in pixels, if present
selectedPosition – The position that will be selected
Returns:
The top-most pixel we can draw the selection into/**
     * Calculate the top-most pixel we can draw the selection into
     *
     * @param childrenTop Top pixel were children can be drawn
     * @param fadingEdgeLength Length of the fading edge in pixels, if present
     * @param selectedPosition The position that will be selected
     * @return The top-most pixel we can draw the selection into
     */
    private int getTopSelectionPixel(int childrenTop, int fadingEdgeLength, int selectedPosition) {
        // first pixel we can draw the selection into
        int topSelectionPixel = childrenTop;
        if (selectedPosition > 0) {
            topSelectionPixel += fadingEdgeLength;
        }
        return topSelectionPixel;
    }

    
Smoothly scroll to the specified adapter position. The view will
scroll such that the indicated position is displayed.
Params:
position – Scroll to this adapter position./**
     * Smoothly scroll to the specified adapter position. The view will
     * scroll such that the indicated position is displayed.
     * @param position Scroll to this adapter position.
     */
    @android.view.RemotableViewMethod
    public void smoothScrollToPosition(int position) {
        super.smoothScrollToPosition(position);
    }

    
Smoothly scroll to the specified adapter position offset. The view will
scroll such that the indicated position is displayed.
Params:
offset – The amount to offset from the adapter position to scroll to./**
     * Smoothly scroll to the specified adapter position offset. The view will
     * scroll such that the indicated position is displayed.
     * @param offset The amount to offset from the adapter position to scroll to.
     */
    @android.view.RemotableViewMethod
    public void smoothScrollByOffset(int offset) {
        super.smoothScrollByOffset(offset);
    }

    
Fills the list based on positioning the new selection relative to the old
selection. The new selection will be placed at, above, or below the
location of the new selection depending on how the selection is moving.
The selection will then be pinned to the visible part of the screen,
excluding the edges that are faded. The list is then filled upwards and
downwards from there.
Params:
oldSel – The old selected view. Useful for trying to put the new
       selection in the same place
newSel – The view that is to become selected. Useful for trying to
       put the new selection in the same place
delta – Which way we are moving
childrenTop – Where to start drawing children
childrenBottom – Last pixel where children can be drawn
Returns:
The view that currently has selection/**
     * Fills the list based on positioning the new selection relative to the old
     * selection. The new selection will be placed at, above, or below the
     * location of the new selection depending on how the selection is moving.
     * The selection will then be pinned to the visible part of the screen,
     * excluding the edges that are faded. The list is then filled upwards and
     * downwards from there.
     *
     * @param oldSel The old selected view. Useful for trying to put the new
     *        selection in the same place
     * @param newSel The view that is to become selected. Useful for trying to
     *        put the new selection in the same place
     * @param delta Which way we are moving
     * @param childrenTop Where to start drawing children
     * @param childrenBottom Last pixel where children can be drawn
     * @return The view that currently has selection
     */
    private View moveSelection(View oldSel, View newSel, int delta, int childrenTop,
            int childrenBottom) {
        int fadingEdgeLength = getVerticalFadingEdgeLength();
        final int selectedPosition = mSelectedPosition;

        View sel;

        final int topSelectionPixel = getTopSelectionPixel(childrenTop, fadingEdgeLength,
                selectedPosition);
        final int bottomSelectionPixel = getBottomSelectionPixel(childrenTop, fadingEdgeLength,
                selectedPosition);

        if (delta > 0) {
            /*
             * Case 1: Scrolling down.
             */

            /*
             *     Before           After
             *    |       |        |       |
             *    +-------+        +-------+
             *    |   A   |        |   A   |
             *    |   1   |   =>   +-------+
             *    +-------+        |   B   |
             *    |   B   |        |   2   |
             *    +-------+        +-------+
             *    |       |        |       |
             *
             *    Try to keep the top of the previously selected item where it was.
             *    oldSel = A
             *    sel = B
             */

            // Put oldSel (A) where it belongs
            oldSel = makeAndAddView(selectedPosition - 1, oldSel.getTop(), true,
                    mListPadding.left, false);

            final int dividerHeight = mDividerHeight;

            // Now put the new selection (B) below that
            sel = makeAndAddView(selectedPosition, oldSel.getBottom() + dividerHeight, true,
                    mListPadding.left, true);

            // Some of the newly selected item extends below the bottom of the list
            if (sel.getBottom() > bottomSelectionPixel) {

                // Find space available above the selection into which we can scroll upwards
                int spaceAbove = sel.getTop() - topSelectionPixel;

                // Find space required to bring the bottom of the selected item fully into view
                int spaceBelow = sel.getBottom() - bottomSelectionPixel;

                // Don't scroll more than half the height of the list
                int halfVerticalSpace = (childrenBottom - childrenTop) / 2;
                int offset = Math.min(spaceAbove, spaceBelow);
                offset = Math.min(offset, halfVerticalSpace);

                // We placed oldSel, so offset that item
                oldSel.offsetTopAndBottom(-offset);
                // Now offset the selected item to get it into view
                sel.offsetTopAndBottom(-offset);
            }

            // Fill in views above and below
            if (!mStackFromBottom) {
                fillUp(mSelectedPosition - 2, sel.getTop() - dividerHeight);
                adjustViewsUpOrDown();
                fillDown(mSelectedPosition + 1, sel.getBottom() + dividerHeight);
            } else {
                fillDown(mSelectedPosition + 1, sel.getBottom() + dividerHeight);
                adjustViewsUpOrDown();
                fillUp(mSelectedPosition - 2, sel.getTop() - dividerHeight);
            }
        } else if (delta < 0) {
            /*
             * Case 2: Scrolling up.
             */

            /*
             *     Before           After
             *    |       |        |       |
             *    +-------+        +-------+
             *    |   A   |        |   A   |
             *    +-------+   =>   |   1   |
             *    |   B   |        +-------+
             *    |   2   |        |   B   |
             *    +-------+        +-------+
             *    |       |        |       |
             *
             *    Try to keep the top of the item about to become selected where it was.
             *    newSel = A
             *    olSel = B
             */

            if (newSel != null) {
                // Try to position the top of newSel (A) where it was before it was selected
                sel = makeAndAddView(selectedPosition, newSel.getTop(), true, mListPadding.left,
                        true);
            } else {
                // If (A) was not on screen and so did not have a view, position
                // it above the oldSel (B)
                sel = makeAndAddView(selectedPosition, oldSel.getTop(), false, mListPadding.left,
                        true);
            }

            // Some of the newly selected item extends above the top of the list
            if (sel.getTop() < topSelectionPixel) {
                // Find space required to bring the top of the selected item fully into view
                int spaceAbove = topSelectionPixel - sel.getTop();

               // Find space available below the selection into which we can scroll downwards
                int spaceBelow = bottomSelectionPixel - sel.getBottom();

                // Don't scroll more than half the height of the list
                int halfVerticalSpace = (childrenBottom - childrenTop) / 2;
                int offset = Math.min(spaceAbove, spaceBelow);
                offset = Math.min(offset, halfVerticalSpace);

                // Offset the selected item to get it into view
                sel.offsetTopAndBottom(offset);
            }

            // Fill in views above and below
            fillAboveAndBelow(sel, selectedPosition);
        } else {

            int oldTop = oldSel.getTop();

            /*
             * Case 3: Staying still
             */
            sel = makeAndAddView(selectedPosition, oldTop, true, mListPadding.left, true);

            // We're staying still...
            if (oldTop < childrenTop) {
                // ... but the top of the old selection was off screen.
                // (This can happen if the data changes size out from under us)
                int newBottom = sel.getBottom();
                if (newBottom < childrenTop + 20) {
                    // Not enough visible -- bring it onscreen
                    sel.offsetTopAndBottom(childrenTop - sel.getTop());
                }
            }

            // Fill in views above and below
            fillAboveAndBelow(sel, selectedPosition);
        }

        return sel;
    }

    private class FocusSelector implements Runnable {
        // the selector is waiting to set selection on the list view
        private static final int STATE_SET_SELECTION = 1;
        // the selector set the selection on the list view, waiting for a layoutChildren pass
        private static final int STATE_WAIT_FOR_LAYOUT = 2;
        // the selector's selection has been honored and it is waiting to request focus on the
        // target child.
        private static final int STATE_REQUEST_FOCUS = 3;

        private int mAction;
        private int mPosition;
        private int mPositionTop;

        FocusSelector setupForSetSelection(int position, int top) {
            mPosition = position;
            mPositionTop = top;
            mAction = STATE_SET_SELECTION;
            return this;
        }

        public void run() {
            if (mAction == STATE_SET_SELECTION) {
                setSelectionFromTop(mPosition, mPositionTop);
                mAction = STATE_WAIT_FOR_LAYOUT;
            } else if (mAction == STATE_REQUEST_FOCUS) {
                final int childIndex = mPosition - mFirstPosition;
                final View child = getChildAt(childIndex);
                if (child != null) {
                    child.requestFocus();
                }
                mAction = -1;
            }
        }

        @Nullable Runnable setupFocusIfValid(int position) {
            if (mAction != STATE_WAIT_FOR_LAYOUT || position != mPosition) {
                return null;
            }
            mAction = STATE_REQUEST_FOCUS;
            return this;
        }

        void onLayoutComplete() {
            if (mAction == STATE_WAIT_FOR_LAYOUT) {
                mAction = -1;
            }
        }
    }

    @Override
    protected void onDetachedFromWindow() {
        if (mFocusSelector != null) {
            removeCallbacks(mFocusSelector);
            mFocusSelector = null;
        }
        super.onDetachedFromWindow();
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        if (getChildCount() > 0) {
            View focusedChild = getFocusedChild();
            if (focusedChild != null) {
                final int childPosition = mFirstPosition + indexOfChild(focusedChild);
                final int childBottom = focusedChild.getBottom();
                final int offset = Math.max(0, childBottom - (h - mPaddingTop));
                final int top = focusedChild.getTop() - offset;
                if (mFocusSelector == null) {
                    mFocusSelector = new FocusSelector();
                }
                post(mFocusSelector.setupForSetSelection(childPosition, top));
            }
        }
        super.onSizeChanged(w, h, oldw, oldh);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        // Sets up mListPadding
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);

        final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
        final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
        int widthSize = MeasureSpec.getSize(widthMeasureSpec);
        int heightSize = MeasureSpec.getSize(heightMeasureSpec);

        int childWidth = 0;
        int childHeight = 0;
        int childState = 0;

        mItemCount = mAdapter == null ? 0 : mAdapter.getCount();
        if (mItemCount > 0 && (widthMode == MeasureSpec.UNSPECIFIED
                || heightMode == MeasureSpec.UNSPECIFIED)) {
            final View child = obtainView(0, mIsScrap);

            // Lay out child directly against the parent measure spec so that
            // we can obtain exected minimum width and height.
            measureScrapChild(child, 0, widthMeasureSpec, heightSize);

            childWidth = child.getMeasuredWidth();
            childHeight = child.getMeasuredHeight();
            childState = combineMeasuredStates(childState, child.getMeasuredState());

            if (recycleOnMeasure() && mRecycler.shouldRecycleViewType(
                    ((LayoutParams) child.getLayoutParams()).viewType)) {
                mRecycler.addScrapView(child, 0);
            }
        }

        if (widthMode == MeasureSpec.UNSPECIFIED) {
            widthSize = mListPadding.left + mListPadding.right + childWidth +
                    getVerticalScrollbarWidth();
        } else {
            widthSize |= (childState & MEASURED_STATE_MASK);
        }

        if (heightMode == MeasureSpec.UNSPECIFIED) {
            heightSize = mListPadding.top + mListPadding.bottom + childHeight +
                    getVerticalFadingEdgeLength() * 2;
        }

        if (heightMode == MeasureSpec.AT_MOST) {
            // TODO: after first layout we should maybe start at the first visible position, not 0
            heightSize = measureHeightOfChildren(widthMeasureSpec, 0, NO_POSITION, heightSize, -1);
        }

        setMeasuredDimension(widthSize, heightSize);

        mWidthMeasureSpec = widthMeasureSpec;
    }

    private void measureScrapChild(View child, int position, int widthMeasureSpec, int heightHint) {
        LayoutParams p = (LayoutParams) child.getLayoutParams();
        if (p == null) {
            p = (AbsListView.LayoutParams) generateDefaultLayoutParams();
            child.setLayoutParams(p);
        }
        p.viewType = mAdapter.getItemViewType(position);
        p.isEnabled = mAdapter.isEnabled(position);
        p.forceAdd = true;

        final int childWidthSpec = ViewGroup.getChildMeasureSpec(widthMeasureSpec,
                mListPadding.left + mListPadding.right, p.width);
        final int lpHeight = p.height;
        final int childHeightSpec;
        if (lpHeight > 0) {
            childHeightSpec = MeasureSpec.makeMeasureSpec(lpHeight, MeasureSpec.EXACTLY);
        } else {
            childHeightSpec = MeasureSpec.makeSafeMeasureSpec(heightHint, MeasureSpec.UNSPECIFIED);
        }
        child.measure(childWidthSpec, childHeightSpec);

        // Since this view was measured directly aginst the parent measure
        // spec, we must measure it again before reuse.
        child.forceLayout();
    }

    
Returns:
True to recycle the views used to measure this ListView in
        UNSPECIFIED/AT_MOST modes, false otherwise.
@hide
/**
     * @return True to recycle the views used to measure this ListView in
     *         UNSPECIFIED/AT_MOST modes, false otherwise.
     * @hide
     */
    @ViewDebug.ExportedProperty(category = "list")
    protected boolean recycleOnMeasure() {
        return true;
    }

    
Measures the height of the given range of children (inclusive) and
returns the height with this ListView's padding and divider heights
included. If maxHeight is provided, the measuring will stop when the
current height reaches maxHeight.
Params:
widthMeasureSpec – The width measure spec to be given to a child's View.measure(int, int).
startPosition – The position of the first child to be shown.
endPosition – The (inclusive) position of the last child to be shown. Specify NO_POSITION if the last child should be the last available child from the adapter.
maxHeight – The maximum height that will be returned (if all the
           children don't fit in this value, this value will be
           returned).
disallowPartialChildPosition – In general, whether the returned
           height should only contain entire children. This is more
           powerful--it is the first inclusive position at which partial
           children will not be allowed. Example: it looks nice to have
           at least 3 completely visible children, and in portrait this
           will most likely fit; but in landscape there could be times
           when even 2 children can not be completely shown, so a value
           of 2 (remember, inclusive) would be good (assuming
           startPosition is 0).
Returns:
The height of this ListView with the given children./**
     * Measures the height of the given range of children (inclusive) and
     * returns the height with this ListView's padding and divider heights
     * included. If maxHeight is provided, the measuring will stop when the
     * current height reaches maxHeight.
     *
     * @param widthMeasureSpec The width measure spec to be given to a child's
     *            {@link View#measure(int, int)}.
     * @param startPosition The position of the first child to be shown.
     * @param endPosition The (inclusive) position of the last child to be
     *            shown. Specify {@link #NO_POSITION} if the last child should be
     *            the last available child from the adapter.
     * @param maxHeight The maximum height that will be returned (if all the
     *            children don't fit in this value, this value will be
     *            returned).
     * @param disallowPartialChildPosition In general, whether the returned
     *            height should only contain entire children. This is more
     *            powerful--it is the first inclusive position at which partial
     *            children will not be allowed. Example: it looks nice to have
     *            at least 3 completely visible children, and in portrait this
     *            will most likely fit; but in landscape there could be times
     *            when even 2 children can not be completely shown, so a value
     *            of 2 (remember, inclusive) would be good (assuming
     *            startPosition is 0).
     * @return The height of this ListView with the given children.
     */
    final int measureHeightOfChildren(int widthMeasureSpec, int startPosition, int endPosition,
            int maxHeight, int disallowPartialChildPosition) {
        final ListAdapter adapter = mAdapter;
        if (adapter == null) {
            return mListPadding.top + mListPadding.bottom;
        }

        // Include the padding of the list
        int returnedHeight = mListPadding.top + mListPadding.bottom;
        final int dividerHeight = mDividerHeight;
        // The previous height value that was less than maxHeight and contained
        // no partial children
        int prevHeightWithoutPartialChild = 0;
        int i;
        View child;

        // mItemCount - 1 since endPosition parameter is inclusive
        endPosition = (endPosition == NO_POSITION) ? adapter.getCount() - 1 : endPosition;
        final AbsListView.RecycleBin recycleBin = mRecycler;
        final boolean recyle = recycleOnMeasure();
        final boolean[] isScrap = mIsScrap;

        for (i = startPosition; i <= endPosition; ++i) {
            child = obtainView(i, isScrap);

            measureScrapChild(child, i, widthMeasureSpec, maxHeight);

            if (i > 0) {
                // Count the divider for all but one child
                returnedHeight += dividerHeight;
            }

            // Recycle the view before we possibly return from the method
            if (recyle && recycleBin.shouldRecycleViewType(
                    ((LayoutParams) child.getLayoutParams()).viewType)) {
                recycleBin.addScrapView(child, -1);
            }

            returnedHeight += child.getMeasuredHeight();

            if (returnedHeight >= maxHeight) {
                // We went over, figure out which height to return.  If returnedHeight > maxHeight,
                // then the i'th position did not fit completely.
                return (disallowPartialChildPosition >= 0) // Disallowing is enabled (> -1)
                            && (i > disallowPartialChildPosition) // We've past the min pos
                            && (prevHeightWithoutPartialChild > 0) // We have a prev height
                            && (returnedHeight != maxHeight) // i'th child did not fit completely
                        ? prevHeightWithoutPartialChild
                        : maxHeight;
            }

            if ((disallowPartialChildPosition >= 0) && (i >= disallowPartialChildPosition)) {
                prevHeightWithoutPartialChild = returnedHeight;
            }
        }

        // At this point, we went through the range of children, and they each
        // completely fit, so return the returnedHeight
        return returnedHeight;
    }

    @Override
    int findMotionRow(int y) {
        int childCount = getChildCount();
        if (childCount > 0) {
            if (!mStackFromBottom) {
                for (int i = 0; i < childCount; i++) {
                    View v = getChildAt(i);
                    if (y <= v.getBottom()) {
                        return mFirstPosition + i;
                    }
                }
            } else {
                for (int i = childCount - 1; i >= 0; i--) {
                    View v = getChildAt(i);
                    if (y >= v.getTop()) {
                        return mFirstPosition + i;
                    }
                }
            }
        }
        return INVALID_POSITION;
    }

    
Put a specific item at a specific location on the screen and then build
up and down from there.
Params:
position – The reference view to use as the starting point
top – Pixel offset from the top of this view to the top of the
       reference view.
Returns:
The selected view, or null if the selected view is outside the
        visible area./**
     * Put a specific item at a specific location on the screen and then build
     * up and down from there.
     *
     * @param position The reference view to use as the starting point
     * @param top Pixel offset from the top of this view to the top of the
     *        reference view.
     *
     * @return The selected view, or null if the selected view is outside the
     *         visible area.
     */
    private View fillSpecific(int position, int top) {
        boolean tempIsSelected = position == mSelectedPosition;
        View temp = makeAndAddView(position, top, true, mListPadding.left, tempIsSelected);
        // Possibly changed again in fillUp if we add rows above this one.
        mFirstPosition = position;

        View above;
        View below;

        final int dividerHeight = mDividerHeight;
        if (!mStackFromBottom) {
            above = fillUp(position - 1, temp.getTop() - dividerHeight);
            // This will correct for the top of the first view not touching the top of the list
            adjustViewsUpOrDown();
            below = fillDown(position + 1, temp.getBottom() + dividerHeight);
            int childCount = getChildCount();
            if (childCount > 0) {
                correctTooHigh(childCount);
            }
        } else {
            below = fillDown(position + 1, temp.getBottom() + dividerHeight);
            // This will correct for the bottom of the last view not touching the bottom of the list
            adjustViewsUpOrDown();
            above = fillUp(position - 1, temp.getTop() - dividerHeight);
            int childCount = getChildCount();
            if (childCount > 0) {
                 correctTooLow(childCount);
            }
        }

        if (tempIsSelected) {
            return temp;
        } else if (above != null) {
            return above;
        } else {
            return below;
        }
    }

    
Check if we have dragged the bottom of the list too high (we have pushed the
top element off the top of the screen when we did not need to). Correct by sliding
everything back down.
Params:
childCount – Number of children/**
     * Check if we have dragged the bottom of the list too high (we have pushed the
     * top element off the top of the screen when we did not need to). Correct by sliding
     * everything back down.
     *
     * @param childCount Number of children
     */
    private void correctTooHigh(int childCount) {
        // First see if the last item is visible. If it is not, it is OK for the
        // top of the list to be pushed up.
        int lastPosition = mFirstPosition + childCount - 1;
        if (lastPosition == mItemCount - 1 && childCount > 0) {

            // Get the last child ...
            final View lastChild = getChildAt(childCount - 1);

            // ... and its bottom edge
            final int lastBottom = lastChild.getBottom();

            // This is bottom of our drawable area
            final int end = (mBottom - mTop) - mListPadding.bottom;

            // This is how far the bottom edge of the last view is from the bottom of the
            // drawable area
            int bottomOffset = end - lastBottom;
            View firstChild = getChildAt(0);
            final int firstTop = firstChild.getTop();

            // Make sure we are 1) Too high, and 2) Either there are more rows above the
            // first row or the first row is scrolled off the top of the drawable area
            if (bottomOffset > 0 && (mFirstPosition > 0 || firstTop < mListPadding.top))  {
                if (mFirstPosition == 0) {
                    // Don't pull the top too far down
                    bottomOffset = Math.min(bottomOffset, mListPadding.top - firstTop);
                }
                // Move everything down
                offsetChildrenTopAndBottom(bottomOffset);
                if (mFirstPosition > 0) {
                    // Fill the gap that was opened above mFirstPosition with more rows, if
                    // possible
                    fillUp(mFirstPosition - 1, firstChild.getTop() - mDividerHeight);
                    // Close up the remaining gap
                    adjustViewsUpOrDown();
                }

            }
        }
    }

    
Check if we have dragged the bottom of the list too low (we have pushed the
bottom element off the bottom of the screen when we did not need to). Correct by sliding
everything back up.
Params:
childCount – Number of children/**
     * Check if we have dragged the bottom of the list too low (we have pushed the
     * bottom element off the bottom of the screen when we did not need to). Correct by sliding
     * everything back up.
     *
     * @param childCount Number of children
     */
    private void correctTooLow(int childCount) {
        // First see if the first item is visible. If it is not, it is OK for the
        // bottom of the list to be pushed down.
        if (mFirstPosition == 0 && childCount > 0) {

            // Get the first child ...
            final View firstChild = getChildAt(0);

            // ... and its top edge
            final int firstTop = firstChild.getTop();

            // This is top of our drawable area
            final int start = mListPadding.top;

            // This is bottom of our drawable area
            final int end = (mBottom - mTop) - mListPadding.bottom;

            // This is how far the top edge of the first view is from the top of the
            // drawable area
            int topOffset = firstTop - start;
            View lastChild = getChildAt(childCount - 1);
            final int lastBottom = lastChild.getBottom();
            int lastPosition = mFirstPosition + childCount - 1;

            // Make sure we are 1) Too low, and 2) Either there are more rows below the
            // last row or the last row is scrolled off the bottom of the drawable area
            if (topOffset > 0) {
                if (lastPosition < mItemCount - 1 || lastBottom > end)  {
                    if (lastPosition == mItemCount - 1) {
                        // Don't pull the bottom too far up
                        topOffset = Math.min(topOffset, lastBottom - end);
                    }
                    // Move everything up
                    offsetChildrenTopAndBottom(-topOffset);
                    if (lastPosition < mItemCount - 1) {
                        // Fill the gap that was opened below the last position with more rows, if
                        // possible
                        fillDown(lastPosition + 1, lastChild.getBottom() + mDividerHeight);
                        // Close up the remaining gap
                        adjustViewsUpOrDown();
                    }
                } else if (lastPosition == mItemCount - 1) {
                    adjustViewsUpOrDown();
                }
            }
        }
    }

    @Override
    protected void layoutChildren() {
        final boolean blockLayoutRequests = mBlockLayoutRequests;
        if (blockLayoutRequests) {
            return;
        }

        mBlockLayoutRequests = true;

        try {
            super.layoutChildren();

            invalidate();

            if (mAdapter == null) {
                resetList();
                invokeOnItemScrollListener();
                return;
            }

            final int childrenTop = mListPadding.top;
            final int childrenBottom = mBottom - mTop - mListPadding.bottom;
            final int childCount = getChildCount();

            int index = 0;
            int delta = 0;

            View sel;
            View oldSel = null;
            View oldFirst = null;
            View newSel = null;

            // Remember stuff we will need down below
            switch (mLayoutMode) {
            case LAYOUT_SET_SELECTION:
                index = mNextSelectedPosition - mFirstPosition;
                if (index >= 0 && index < childCount) {
                    newSel = getChildAt(index);
                }
                break;
            case LAYOUT_FORCE_TOP:
            case LAYOUT_FORCE_BOTTOM:
            case LAYOUT_SPECIFIC:
            case LAYOUT_SYNC:
                break;
            case LAYOUT_MOVE_SELECTION:
            default:
                // Remember the previously selected view
                index = mSelectedPosition - mFirstPosition;
                if (index >= 0 && index < childCount) {
                    oldSel = getChildAt(index);
                }

                // Remember the previous first child
                oldFirst = getChildAt(0);

                if (mNextSelectedPosition >= 0) {
                    delta = mNextSelectedPosition - mSelectedPosition;
                }

                // Caution: newSel might be null
                newSel = getChildAt(index + delta);
            }


            boolean dataChanged = mDataChanged;
            if (dataChanged) {
                handleDataChanged();
            }

            // Handle the empty set by removing all views that are visible
            // and calling it a day
            if (mItemCount == 0) {
                resetList();
                invokeOnItemScrollListener();
                return;
            } else if (mItemCount != mAdapter.getCount()) {
                throw new IllegalStateException("The content of the adapter has changed but "
                        + "ListView did not receive a notification. Make sure the content of "
                        + "your adapter is not modified from a background thread, but only from "
                        + "the UI thread. Make sure your adapter calls notifyDataSetChanged() "
                        + "when its content changes. [in ListView(" + getId() + ", " + getClass()
                        + ") with Adapter(" + mAdapter.getClass() + ")]");
            }

            setSelectedPositionInt(mNextSelectedPosition);

            AccessibilityNodeInfo accessibilityFocusLayoutRestoreNode = null;
            View accessibilityFocusLayoutRestoreView = null;
            int accessibilityFocusPosition = INVALID_POSITION;

            // Remember which child, if any, had accessibility focus. This must
            // occur before recycling any views, since that will clear
            // accessibility focus.
            final ViewRootImpl viewRootImpl = getViewRootImpl();
            if (viewRootImpl != null) {
                final View focusHost = viewRootImpl.getAccessibilityFocusedHost();
                if (focusHost != null) {
                    final View focusChild = getAccessibilityFocusedChild(focusHost);
                    if (focusChild != null) {
                        if (!dataChanged || isDirectChildHeaderOrFooter(focusChild)
                                || (focusChild.hasTransientState() && mAdapterHasStableIds)) {
                            // The views won't be changing, so try to maintain
                            // focus on the current host and virtual view.
                            accessibilityFocusLayoutRestoreView = focusHost;
                            accessibilityFocusLayoutRestoreNode = viewRootImpl
                                    .getAccessibilityFocusedVirtualView();
                        }

                        // If all else fails, maintain focus at the same
                        // position.
                        accessibilityFocusPosition = getPositionForView(focusChild);
                    }
                }
            }

            View focusLayoutRestoreDirectChild = null;
            View focusLayoutRestoreView = null;

            // Take focus back to us temporarily to avoid the eventual call to
            // clear focus when removing the focused child below from messing
            // things up when ViewAncestor assigns focus back to someone else.
            final View focusedChild = getFocusedChild();
            if (focusedChild != null) {
                // TODO: in some cases focusedChild.getParent() == null

                // We can remember the focused view to restore after re-layout
                // if the data hasn't changed, or if the focused position is a
                // header or footer.
                if (!dataChanged || isDirectChildHeaderOrFooter(focusedChild)
                        || focusedChild.hasTransientState() || mAdapterHasStableIds) {
                    focusLayoutRestoreDirectChild = focusedChild;
                    // Remember the specific view that had focus.
                    focusLayoutRestoreView = findFocus();
                    if (focusLayoutRestoreView != null) {
                        // Tell it we are going to mess with it.
                        focusLayoutRestoreView.dispatchStartTemporaryDetach();
                    }
                }
                requestFocus();
            }

            // Pull all children into the RecycleBin.
            // These views will be reused if possible
            final int firstPosition = mFirstPosition;
            final RecycleBin recycleBin = mRecycler;
            if (dataChanged) {
                for (int i = 0; i < childCount; i++) {
                    recycleBin.addScrapView(getChildAt(i), firstPosition+i);
                }
            } else {
                recycleBin.fillActiveViews(childCount, firstPosition);
            }

            // Clear out old views
            detachAllViewsFromParent();
            recycleBin.removeSkippedScrap();

            switch (mLayoutMode) {
            case LAYOUT_SET_SELECTION:
                if (newSel != null) {
                    sel = fillFromSelection(newSel.getTop(), childrenTop, childrenBottom);
                } else {
                    sel = fillFromMiddle(childrenTop, childrenBottom);
                }
                break;
            case LAYOUT_SYNC:
                sel = fillSpecific(mSyncPosition, mSpecificTop);
                break;
            case LAYOUT_FORCE_BOTTOM:
                sel = fillUp(mItemCount - 1, childrenBottom);
                adjustViewsUpOrDown();
                break;
            case LAYOUT_FORCE_TOP:
                mFirstPosition = 0;
                sel = fillFromTop(childrenTop);
                adjustViewsUpOrDown();
                break;
            case LAYOUT_SPECIFIC:
                final int selectedPosition = reconcileSelectedPosition();
                sel = fillSpecific(selectedPosition, mSpecificTop);
                /**
                 * When ListView is resized, FocusSelector requests an async selection for the
                 * previously focused item to make sure it is still visible. If the item is not
                 * selectable, it won't regain focus so instead we call FocusSelector
                 * to directly request focus on the view after it is visible.
                 */
                if (sel == null && mFocusSelector != null) {
                    final Runnable focusRunnable = mFocusSelector
                            .setupFocusIfValid(selectedPosition);
                    if (focusRunnable != null) {
                        post(focusRunnable);
                    }
                }
                break;
            case LAYOUT_MOVE_SELECTION:
                sel = moveSelection(oldSel, newSel, delta, childrenTop, childrenBottom);
                break;
            default:
                if (childCount == 0) {
                    if (!mStackFromBottom) {
                        final int position = lookForSelectablePosition(0, true);
                        setSelectedPositionInt(position);
                        sel = fillFromTop(childrenTop);
                    } else {
                        final int position = lookForSelectablePosition(mItemCount - 1, false);
                        setSelectedPositionInt(position);
                        sel = fillUp(mItemCount - 1, childrenBottom);
                    }
                } else {
                    if (mSelectedPosition >= 0 && mSelectedPosition < mItemCount) {
                        sel = fillSpecific(mSelectedPosition,
                                oldSel == null ? childrenTop : oldSel.getTop());
                    } else if (mFirstPosition < mItemCount) {
                        sel = fillSpecific(mFirstPosition,
                                oldFirst == null ? childrenTop : oldFirst.getTop());
                    } else {
                        sel = fillSpecific(0, childrenTop);
                    }
                }
                break;
            }

            // Flush any cached views that did not get reused above
            recycleBin.scrapActiveViews();

            // remove any header/footer that has been temp detached and not re-attached
            removeUnusedFixedViews(mHeaderViewInfos);
            removeUnusedFixedViews(mFooterViewInfos);

            if (sel != null) {
                // The current selected item should get focus if items are
                // focusable.
                if (mItemsCanFocus && hasFocus() && !sel.hasFocus()) {
                    final boolean focusWasTaken = (sel == focusLayoutRestoreDirectChild &&
                            focusLayoutRestoreView != null &&
                            focusLayoutRestoreView.requestFocus()) || sel.requestFocus();
                    if (!focusWasTaken) {
                        // Selected item didn't take focus, but we still want to
                        // make sure something else outside of the selected view
                        // has focus.
                        final View focused = getFocusedChild();
                        if (focused != null) {
                            focused.clearFocus();
                        }
                        positionSelector(INVALID_POSITION, sel);
                    } else {
                        sel.setSelected(false);
                        mSelectorRect.setEmpty();
                    }
                } else {
                    positionSelector(INVALID_POSITION, sel);
                }
                mSelectedTop = sel.getTop();
            } else {
                final boolean inTouchMode = mTouchMode == TOUCH_MODE_TAP
                        || mTouchMode == TOUCH_MODE_DONE_WAITING;
                if (inTouchMode) {
                    // If the user's finger is down, select the motion position.
                    final View child = getChildAt(mMotionPosition - mFirstPosition);
                    if (child != null) {
                        positionSelector(mMotionPosition, child);
                    }
                } else if (mSelectorPosition != INVALID_POSITION) {
                    // If we had previously positioned the selector somewhere,
                    // put it back there. It might not match up with the data,
                    // but it's transitioning out so it's not a big deal.
                    final View child = getChildAt(mSelectorPosition - mFirstPosition);
                    if (child != null) {
                        positionSelector(mSelectorPosition, child);
                    }
                } else {
                    // Otherwise, clear selection.
                    mSelectedTop = 0;
                    mSelectorRect.setEmpty();
                }

                // Even if there is not selected position, we may need to
                // restore focus (i.e. something focusable in touch mode).
                if (hasFocus() && focusLayoutRestoreView != null) {
                    focusLayoutRestoreView.requestFocus();
                }
            }

            // Attempt to restore accessibility focus, if necessary.
            if (viewRootImpl != null) {
                final View newAccessibilityFocusedView = viewRootImpl.getAccessibilityFocusedHost();
                if (newAccessibilityFocusedView == null) {
                    if (accessibilityFocusLayoutRestoreView != null
                            && accessibilityFocusLayoutRestoreView.isAttachedToWindow()) {
                        final AccessibilityNodeProvider provider =
                                accessibilityFocusLayoutRestoreView.getAccessibilityNodeProvider();
                        if (accessibilityFocusLayoutRestoreNode != null && provider != null) {
                            final int virtualViewId = AccessibilityNodeInfo.getVirtualDescendantId(
                                    accessibilityFocusLayoutRestoreNode.getSourceNodeId());
                            provider.performAction(virtualViewId,
                                    AccessibilityNodeInfo.ACTION_ACCESSIBILITY_FOCUS, null);
                        } else {
                            accessibilityFocusLayoutRestoreView.requestAccessibilityFocus();
                        }
                    } else if (accessibilityFocusPosition != INVALID_POSITION) {
                        // Bound the position within the visible children.
                        final int position = MathUtils.constrain(
                                accessibilityFocusPosition - mFirstPosition, 0,
                                getChildCount() - 1);
                        final View restoreView = getChildAt(position);
                        if (restoreView != null) {
                            restoreView.requestAccessibilityFocus();
                        }
                    }
                }
            }

            // Tell focus view we are done mucking with it, if it is still in
            // our view hierarchy.
            if (focusLayoutRestoreView != null
                    && focusLayoutRestoreView.getWindowToken() != null) {
                focusLayoutRestoreView.dispatchFinishTemporaryDetach();
            }

            mLayoutMode = LAYOUT_NORMAL;
            mDataChanged = false;
            if (mPositionScrollAfterLayout != null) {
                post(mPositionScrollAfterLayout);
                mPositionScrollAfterLayout = null;
            }
            mNeedSync = false;
            setNextSelectedPositionInt(mSelectedPosition);

            updateScrollIndicators();

            if (mItemCount > 0) {
                checkSelectionChanged();
            }

            invokeOnItemScrollListener();
        } finally {
            if (mFocusSelector != null) {
                mFocusSelector.onLayoutComplete();
            }
            if (!blockLayoutRequests) {
                mBlockLayoutRequests = false;
            }
        }
    }

    @Override
    boolean trackMotionScroll(int deltaY, int incrementalDeltaY) {
        final boolean result = super.trackMotionScroll(deltaY, incrementalDeltaY);
        removeUnusedFixedViews(mHeaderViewInfos);
        removeUnusedFixedViews(mFooterViewInfos);
        return result;
    }

    
Header and Footer views are not scrapped / recycled like other views but they are still
detached from the ViewGroup. After a layout operation, call this method to remove such views.
Params:
infoList – The info list to be traversed/**
     * Header and Footer views are not scrapped / recycled like other views but they are still
     * detached from the ViewGroup. After a layout operation, call this method to remove such views.
     *
     * @param infoList The info list to be traversed
     */
    private void removeUnusedFixedViews(@Nullable List<FixedViewInfo> infoList) {
        if (infoList == null) {
            return;
        }
        for (int i = infoList.size() - 1; i >= 0; i--) {
            final FixedViewInfo fixedViewInfo = infoList.get(i);
            final View view = fixedViewInfo.view;
            final LayoutParams lp = (LayoutParams) view.getLayoutParams();
            if (view.getParent() == null && lp != null && lp.recycledHeaderFooter) {
                removeDetachedView(view, false);
                lp.recycledHeaderFooter = false;
            }

        }
    }

    
Params:
child – a direct child of this list.
Returns:
Whether child is a header or footer view./**
     * @param child a direct child of this list.
     * @return Whether child is a header or footer view.
     */
    private boolean isDirectChildHeaderOrFooter(View child) {
        final ArrayList<FixedViewInfo> headers = mHeaderViewInfos;
        final int numHeaders = headers.size();
        for (int i = 0; i < numHeaders; i++) {
            if (child == headers.get(i).view) {
                return true;
            }
        }

        final ArrayList<FixedViewInfo> footers = mFooterViewInfos;
        final int numFooters = footers.size();
        for (int i = 0; i < numFooters; i++) {
            if (child == footers.get(i).view) {
                return true;
            }
        }

        return false;
    }

    
Obtains the view and adds it to our list of children. The view can be
made fresh, converted from an unused view, or used as is if it was in
the recycle bin.
Params:
position – logical position in the list
y – top or bottom edge of the view to add
flow – true to align top edge to y, false to align bottom edge to y
childrenLeft – left edge where children should be positioned
selected – true if the position is selected, false otherwise
Returns:
the view that was added/**
     * Obtains the view and adds it to our list of children. The view can be
     * made fresh, converted from an unused view, or used as is if it was in
     * the recycle bin.
     *
     * @param position logical position in the list
     * @param y top or bottom edge of the view to add
     * @param flow {@code true} to align top edge to y, {@code false} to align
     *             bottom edge to y
     * @param childrenLeft left edge where children should be positioned
     * @param selected {@code true} if the position is selected, {@code false}
     *                 otherwise
     * @return the view that was added
     */
    private View makeAndAddView(int position, int y, boolean flow, int childrenLeft,
            boolean selected) {
        if (!mDataChanged) {
            // Try to use an existing view for this position.
            final View activeView = mRecycler.getActiveView(position);
            if (activeView != null) {
                // Found it. We're reusing an existing child, so it just needs
                // to be positioned like a scrap view.
                setupChild(activeView, position, y, flow, childrenLeft, selected, true);
                return activeView;
            }
        }

        // Make a new view for this position, or convert an unused view if
        // possible.
        final View child = obtainView(position, mIsScrap);

        // This needs to be positioned and measured.
        setupChild(child, position, y, flow, childrenLeft, selected, mIsScrap[0]);

        return child;
    }

    
Adds a view as a child and make sure it is measured (if necessary) and
positioned properly.
Params:
child – the view to add
position – the position of this child
y – the y position relative to which this view will be positioned
flowDown – true to align top edge to y, false to align bottom edge to y
childrenLeft – left edge where children should be positioned
selected – true if the position is selected, false otherwise
isAttachedToWindow – true if the view is already attached to the window, e.g. whether it was reused, or false otherwise/**
     * Adds a view as a child and make sure it is measured (if necessary) and
     * positioned properly.
     *
     * @param child the view to add
     * @param position the position of this child
     * @param y the y position relative to which this view will be positioned
     * @param flowDown {@code true} to align top edge to y, {@code false} to
     *                 align bottom edge to y
     * @param childrenLeft left edge where children should be positioned
     * @param selected {@code true} if the position is selected, {@code false}
     *                 otherwise
     * @param isAttachedToWindow {@code true} if the view is already attached
     *                           to the window, e.g. whether it was reused, or
     *                           {@code false} otherwise
     */
    private void setupChild(View child, int position, int y, boolean flowDown, int childrenLeft,
            boolean selected, boolean isAttachedToWindow) {
        Trace.traceBegin(Trace.TRACE_TAG_VIEW, "setupListItem");

        final boolean isSelected = selected && shouldShowSelector();
        final boolean updateChildSelected = isSelected != child.isSelected();
        final int mode = mTouchMode;
        final boolean isPressed = mode > TOUCH_MODE_DOWN && mode < TOUCH_MODE_SCROLL
                && mMotionPosition == position;
        final boolean updateChildPressed = isPressed != child.isPressed();
        final boolean needToMeasure = !isAttachedToWindow || updateChildSelected
                || child.isLayoutRequested();

        // Respect layout params that are already in the view. Otherwise make
        // some up...
        AbsListView.LayoutParams p = (AbsListView.LayoutParams) child.getLayoutParams();
        if (p == null) {
            p = (AbsListView.LayoutParams) generateDefaultLayoutParams();
        }
        p.viewType = mAdapter.getItemViewType(position);
        p.isEnabled = mAdapter.isEnabled(position);

        // Set up view state before attaching the view, since we may need to
        // rely on the jumpDrawablesToCurrentState() call that occurs as part
        // of view attachment.
        if (updateChildSelected) {
            child.setSelected(isSelected);
        }

        if (updateChildPressed) {
            child.setPressed(isPressed);
        }

        if (mChoiceMode != CHOICE_MODE_NONE && mCheckStates != null) {
            if (child instanceof Checkable) {
                ((Checkable) child).setChecked(mCheckStates.get(position));
            } else if (getContext().getApplicationInfo().targetSdkVersion
                    >= android.os.Build.VERSION_CODES.HONEYCOMB) {
                child.setActivated(mCheckStates.get(position));
            }
        }

        if ((isAttachedToWindow && !p.forceAdd) || (p.recycledHeaderFooter
                && p.viewType == AdapterView.ITEM_VIEW_TYPE_HEADER_OR_FOOTER)) {
            attachViewToParent(child, flowDown ? -1 : 0, p);

            // If the view was previously attached for a different position,
            // then manually jump the drawables.
            if (isAttachedToWindow
                    && (((AbsListView.LayoutParams) child.getLayoutParams()).scrappedFromPosition)
                            != position) {
                child.jumpDrawablesToCurrentState();
            }
        } else {
            p.forceAdd = false;
            if (p.viewType == AdapterView.ITEM_VIEW_TYPE_HEADER_OR_FOOTER) {
                p.recycledHeaderFooter = true;
            }
            addViewInLayout(child, flowDown ? -1 : 0, p, true);
            // add view in layout will reset the RTL properties. We have to re-resolve them
            child.resolveRtlPropertiesIfNeeded();
        }

        if (needToMeasure) {
            final int childWidthSpec = ViewGroup.getChildMeasureSpec(mWidthMeasureSpec,
                    mListPadding.left + mListPadding.right, p.width);
            final int lpHeight = p.height;
            final int childHeightSpec;
            if (lpHeight > 0) {
                childHeightSpec = MeasureSpec.makeMeasureSpec(lpHeight, MeasureSpec.EXACTLY);
            } else {
                childHeightSpec = MeasureSpec.makeSafeMeasureSpec(getMeasuredHeight(),
                        MeasureSpec.UNSPECIFIED);
            }
            child.measure(childWidthSpec, childHeightSpec);
        } else {
            cleanupLayoutState(child);
        }

        final int w = child.getMeasuredWidth();
        final int h = child.getMeasuredHeight();
        final int childTop = flowDown ? y : y - h;

        if (needToMeasure) {
            final int childRight = childrenLeft + w;
            final int childBottom = childTop + h;
            child.layout(childrenLeft, childTop, childRight, childBottom);
        } else {
            child.offsetLeftAndRight(childrenLeft - child.getLeft());
            child.offsetTopAndBottom(childTop - child.getTop());
        }

        if (mCachingStarted && !child.isDrawingCacheEnabled()) {
            child.setDrawingCacheEnabled(true);
        }

        Trace.traceEnd(Trace.TRACE_TAG_VIEW);
    }

    @Override
    protected boolean canAnimate() {
        return super.canAnimate() && mItemCount > 0;
    }

    
Sets the currently selected item. If in touch mode, the item will not be selected
but it will still be positioned appropriately. If the specified selection position
is less than 0, then the item at position 0 will be selected.
Params:
position – Index (starting at 0) of the data item to be selected./**
     * Sets the currently selected item. If in touch mode, the item will not be selected
     * but it will still be positioned appropriately. If the specified selection position
     * is less than 0, then the item at position 0 will be selected.
     *
     * @param position Index (starting at 0) of the data item to be selected.
     */
    @Override
    public void setSelection(int position) {
        setSelectionFromTop(position, 0);
    }

    
Makes the item at the supplied position selected.
Params:
position – the position of the item to select/**
     * Makes the item at the supplied position selected.
     *
     * @param position the position of the item to select
     */
    @Override
    void setSelectionInt(int position) {
        setNextSelectedPositionInt(position);
        boolean awakeScrollbars = false;

        final int selectedPosition = mSelectedPosition;

        if (selectedPosition >= 0) {
            if (position == selectedPosition - 1) {
                awakeScrollbars = true;
            } else if (position == selectedPosition + 1) {
                awakeScrollbars = true;
            }
        }

        if (mPositionScroller != null) {
            mPositionScroller.stop();
        }

        layoutChildren();

        if (awakeScrollbars) {
            awakenScrollBars();
        }
    }

    
Find a position that can be selected (i.e., is not a separator).
Params:
position – The starting position to look at.
lookDown – Whether to look down for other positions.
Returns:
The next selectable position starting at position and then searching either up or down. Returns AdapterView<ListAdapter>.INVALID_POSITION if nothing can be found./**
     * Find a position that can be selected (i.e., is not a separator).
     *
     * @param position The starting position to look at.
     * @param lookDown Whether to look down for other positions.
     * @return The next selectable position starting at position and then searching either up or
     *         down. Returns {@link #INVALID_POSITION} if nothing can be found.
     */
    @Override
    int lookForSelectablePosition(int position, boolean lookDown) {
        final ListAdapter adapter = mAdapter;
        if (adapter == null || isInTouchMode()) {
            return INVALID_POSITION;
        }

        final int count = adapter.getCount();
        if (!mAreAllItemsSelectable) {
            if (lookDown) {
                position = Math.max(0, position);
                while (position < count && !adapter.isEnabled(position)) {
                    position++;
                }
            } else {
                position = Math.min(position, count - 1);
                while (position >= 0 && !adapter.isEnabled(position)) {
                    position--;
                }
            }
        }

        if (position < 0 || position >= count) {
            return INVALID_POSITION;
        }

        return position;
    }

    
Find a position that can be selected (i.e., is not a separator). If there
are no selectable positions in the specified direction from the starting
position, searches in the opposite direction from the starting position
to the current position.
Params:
current – the current position
position – the starting position
lookDown – whether to look down for other positions
Returns:
the next selectable position, or AdapterView<ListAdapter>.INVALID_POSITION if nothing can be found/**
     * Find a position that can be selected (i.e., is not a separator). If there
     * are no selectable positions in the specified direction from the starting
     * position, searches in the opposite direction from the starting position
     * to the current position.
     *
     * @param current the current position
     * @param position the starting position
     * @param lookDown whether to look down for other positions
     * @return the next selectable position, or {@link #INVALID_POSITION} if
     *         nothing can be found
     */
    int lookForSelectablePositionAfter(int current, int position, boolean lookDown) {
        final ListAdapter adapter = mAdapter;
        if (adapter == null || isInTouchMode()) {
            return INVALID_POSITION;
        }

        // First check after the starting position in the specified direction.
        final int after = lookForSelectablePosition(position, lookDown);
        if (after != INVALID_POSITION) {
            return after;
        }

        // Then check between the starting position and the current position.
        final int count = adapter.getCount();
        current = MathUtils.constrain(current, -1, count - 1);
        if (lookDown) {
            position = Math.min(position - 1, count - 1);
            while ((position > current) && !adapter.isEnabled(position)) {
                position--;
            }
            if (position <= current) {
                return INVALID_POSITION;
            }
        } else {
            position = Math.max(0, position + 1);
            while ((position < current) && !adapter.isEnabled(position)) {
                position++;
            }
            if (position >= current) {
                return INVALID_POSITION;
            }
        }

        return position;
    }

    
setSelectionAfterHeaderView set the selection to be the first list item
after the header views.
/**
     * setSelectionAfterHeaderView set the selection to be the first list item
     * after the header views.
     */
    public void setSelectionAfterHeaderView() {
        final int count = getHeaderViewsCount();
        if (count > 0) {
            mNextSelectedPosition = 0;
            return;
        }

        if (mAdapter != null) {
            setSelection(count);
        } else {
            mNextSelectedPosition = count;
            mLayoutMode = LAYOUT_SET_SELECTION;
        }

    }

    @Override
    public boolean dispatchKeyEvent(KeyEvent event) {
        // Dispatch in the normal way
        boolean handled = super.dispatchKeyEvent(event);
        if (!handled) {
            // If we didn't handle it...
            View focused = getFocusedChild();
            if (focused != null && event.getAction() == KeyEvent.ACTION_DOWN) {
                // ... and our focused child didn't handle it
                // ... give it to ourselves so we can scroll if necessary
                handled = onKeyDown(event.getKeyCode(), event);
            }
        }
        return handled;
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        return commonKey(keyCode, 1, event);
    }

    @Override
    public boolean onKeyMultiple(int keyCode, int repeatCount, KeyEvent event) {
        return commonKey(keyCode, repeatCount, event);
    }

    @Override
    public boolean onKeyUp(int keyCode, KeyEvent event) {
        return commonKey(keyCode, 1, event);
    }

    private boolean commonKey(int keyCode, int count, KeyEvent event) {
        if (mAdapter == null || !isAttachedToWindow()) {
            return false;
        }

        if (mDataChanged) {
            layoutChildren();
        }

        boolean handled = false;
        int action = event.getAction();
        if (KeyEvent.isConfirmKey(keyCode)
                && event.hasNoModifiers() && action != KeyEvent.ACTION_UP) {
            handled = resurrectSelectionIfNeeded();
            if (!handled && event.getRepeatCount() == 0 && getChildCount() > 0) {
                keyPressed();
                handled = true;
            }
        }


        if (!handled && action != KeyEvent.ACTION_UP) {
            switch (keyCode) {
            case KeyEvent.KEYCODE_DPAD_UP:
                if (event.hasNoModifiers()) {
                    handled = resurrectSelectionIfNeeded();
                    if (!handled) {
                        while (count-- > 0) {
                            if (arrowScroll(FOCUS_UP)) {
                                handled = true;
                            } else {
                                break;
                            }
                        }
                    }
                } else if (event.hasModifiers(KeyEvent.META_ALT_ON)) {
                    handled = resurrectSelectionIfNeeded() || fullScroll(FOCUS_UP);
                }
                break;

            case KeyEvent.KEYCODE_DPAD_DOWN:
                if (event.hasNoModifiers()) {
                    handled = resurrectSelectionIfNeeded();
                    if (!handled) {
                        while (count-- > 0) {
                            if (arrowScroll(FOCUS_DOWN)) {
                                handled = true;
                            } else {
                                break;
                            }
                        }
                    }
                } else if (event.hasModifiers(KeyEvent.META_ALT_ON)) {
                    handled = resurrectSelectionIfNeeded() || fullScroll(FOCUS_DOWN);
                }
                break;

            case KeyEvent.KEYCODE_DPAD_LEFT:
                if (event.hasNoModifiers()) {
                    handled = handleHorizontalFocusWithinListItem(View.FOCUS_LEFT);
                }
                break;

            case KeyEvent.KEYCODE_DPAD_RIGHT:
                if (event.hasNoModifiers()) {
                    handled = handleHorizontalFocusWithinListItem(View.FOCUS_RIGHT);
                }
                break;

            case KeyEvent.KEYCODE_PAGE_UP:
                if (event.hasNoModifiers()) {
                    handled = resurrectSelectionIfNeeded() || pageScroll(FOCUS_UP);
                } else if (event.hasModifiers(KeyEvent.META_ALT_ON)) {
                    handled = resurrectSelectionIfNeeded() || fullScroll(FOCUS_UP);
                }
                break;

            case KeyEvent.KEYCODE_PAGE_DOWN:
                if (event.hasNoModifiers()) {
                    handled = resurrectSelectionIfNeeded() || pageScroll(FOCUS_DOWN);
                } else if (event.hasModifiers(KeyEvent.META_ALT_ON)) {
                    handled = resurrectSelectionIfNeeded() || fullScroll(FOCUS_DOWN);
                }
                break;

            case KeyEvent.KEYCODE_MOVE_HOME:
                if (event.hasNoModifiers()) {
                    handled = resurrectSelectionIfNeeded() || fullScroll(FOCUS_UP);
                }
                break;

            case KeyEvent.KEYCODE_MOVE_END:
                if (event.hasNoModifiers()) {
                    handled = resurrectSelectionIfNeeded() || fullScroll(FOCUS_DOWN);
                }
                break;

            case KeyEvent.KEYCODE_TAB:
                // This creates an asymmetry in TAB navigation order. At some
                // point in the future we may decide that it's preferable to
                // force the list selection to the top or bottom when receiving
                // TAB focus from another widget, but for now this is adequate.
                if (event.hasNoModifiers()) {
                    handled = resurrectSelectionIfNeeded() || arrowScroll(FOCUS_DOWN);
                } else if (event.hasModifiers(KeyEvent.META_SHIFT_ON)) {
                    handled = resurrectSelectionIfNeeded() || arrowScroll(FOCUS_UP);
                }
                break;
            }
        }

        if (handled) {
            return true;
        }

        if (sendToTextFilter(keyCode, count, event)) {
            return true;
        }

        switch (action) {
            case KeyEvent.ACTION_DOWN:
                return super.onKeyDown(keyCode, event);

            case KeyEvent.ACTION_UP:
                return super.onKeyUp(keyCode, event);

            case KeyEvent.ACTION_MULTIPLE:
                return super.onKeyMultiple(keyCode, count, event);

            default: // shouldn't happen
                return false;
        }
    }

    
Scrolls up or down by the number of items currently present on screen.
Params:
direction – either View.FOCUS_UP or View.FOCUS_DOWN
Returns:
whether selection was moved/**
     * Scrolls up or down by the number of items currently present on screen.
     *
     * @param direction either {@link View#FOCUS_UP} or {@link View#FOCUS_DOWN}
     * @return whether selection was moved
     */
    boolean pageScroll(int direction) {
        final int nextPage;
        final boolean down;

        if (direction == FOCUS_UP) {
            nextPage = Math.max(0, mSelectedPosition - getChildCount() - 1);
            down = false;
        } else if (direction == FOCUS_DOWN) {
            nextPage = Math.min(mItemCount - 1, mSelectedPosition + getChildCount() - 1);
            down = true;
        } else {
            return false;
        }

        if (nextPage >= 0) {
            final int position = lookForSelectablePositionAfter(mSelectedPosition, nextPage, down);
            if (position >= 0) {
                mLayoutMode = LAYOUT_SPECIFIC;
                mSpecificTop = mPaddingTop + getVerticalFadingEdgeLength();

                if (down && (position > (mItemCount - getChildCount()))) {
                    mLayoutMode = LAYOUT_FORCE_BOTTOM;
                }

                if (!down && (position < getChildCount())) {
                    mLayoutMode = LAYOUT_FORCE_TOP;
                }

                setSelectionInt(position);
                invokeOnItemScrollListener();
                if (!awakenScrollBars()) {
                    invalidate();
                }

                return true;
            }
        }

        return false;
    }

    
Go to the last or first item if possible (not worrying about panning
across or navigating within the internal focus of the currently selected
item.)
Params:
direction – either View.FOCUS_UP or View.FOCUS_DOWN
Returns:
whether selection was moved/**
     * Go to the last or first item if possible (not worrying about panning
     * across or navigating within the internal focus of the currently selected
     * item.)
     *
     * @param direction either {@link View#FOCUS_UP} or {@link View#FOCUS_DOWN}
     * @return whether selection was moved
     */
    boolean fullScroll(int direction) {
        boolean moved = false;
        if (direction == FOCUS_UP) {
            if (mSelectedPosition != 0) {
                final int position = lookForSelectablePositionAfter(mSelectedPosition, 0, true);
                if (position >= 0) {
                    mLayoutMode = LAYOUT_FORCE_TOP;
                    setSelectionInt(position);
                    invokeOnItemScrollListener();
                }
                moved = true;
            }
        } else if (direction == FOCUS_DOWN) {
            final int lastItem = (mItemCount - 1);
            if (mSelectedPosition < lastItem) {
                final int position = lookForSelectablePositionAfter(
                        mSelectedPosition, lastItem, false);
                if (position >= 0) {
                    mLayoutMode = LAYOUT_FORCE_BOTTOM;
                    setSelectionInt(position);
                    invokeOnItemScrollListener();
                }
                moved = true;
            }
        }

        if (moved && !awakenScrollBars()) {
            awakenScrollBars();
            invalidate();
        }

        return moved;
    }

    
To avoid horizontal focus searches changing the selected item, we
manually focus search within the selected item (as applicable), and
prevent focus from jumping to something within another item.
Params:
direction – one of {View.FOCUS_LEFT, View.FOCUS_RIGHT}
Returns:
Whether this consumes the key event./**
     * To avoid horizontal focus searches changing the selected item, we
     * manually focus search within the selected item (as applicable), and
     * prevent focus from jumping to something within another item.
     * @param direction one of {View.FOCUS_LEFT, View.FOCUS_RIGHT}
     * @return Whether this consumes the key event.
     */
    private boolean handleHorizontalFocusWithinListItem(int direction) {
        if (direction != View.FOCUS_LEFT && direction != View.FOCUS_RIGHT)  {
            throw new IllegalArgumentException("direction must be one of"
                    + " {View.FOCUS_LEFT, View.FOCUS_RIGHT}");
        }

        final int numChildren = getChildCount();
        if (mItemsCanFocus && numChildren > 0 && mSelectedPosition != INVALID_POSITION) {
            final View selectedView = getSelectedView();
            if (selectedView != null && selectedView.hasFocus() &&
                    selectedView instanceof ViewGroup) {

                final View currentFocus = selectedView.findFocus();
                final View nextFocus = FocusFinder.getInstance().findNextFocus(
                        (ViewGroup) selectedView, currentFocus, direction);
                if (nextFocus != null) {
                    // do the math to get interesting rect in next focus' coordinates
                    Rect focusedRect = mTempRect;
                    if (currentFocus != null) {
                        currentFocus.getFocusedRect(focusedRect);
                        offsetDescendantRectToMyCoords(currentFocus, focusedRect);
                        offsetRectIntoDescendantCoords(nextFocus, focusedRect);
                    } else {
                        focusedRect = null;
                    }
                    if (nextFocus.requestFocus(direction, focusedRect)) {
                        return true;
                    }
                }
                // we are blocking the key from being handled (by returning true)
                // if the global result is going to be some other view within this
                // list.  this is to acheive the overall goal of having
                // horizontal d-pad navigation remain in the current item.
                final View globalNextFocus = FocusFinder.getInstance().findNextFocus(
                        (ViewGroup) getRootView(), currentFocus, direction);
                if (globalNextFocus != null) {
                    return isViewAncestorOf(globalNextFocus, this);
                }
            }
        }
        return false;
    }

    
Scrolls to the next or previous item if possible.
Params:
direction – either View.FOCUS_UP or View.FOCUS_DOWN
Returns:
whether selection was moved/**
     * Scrolls to the next or previous item if possible.
     *
     * @param direction either {@link View#FOCUS_UP} or {@link View#FOCUS_DOWN}
     *
     * @return whether selection was moved
     */
    boolean arrowScroll(int direction) {
        try {
            mInLayout = true;
            final boolean handled = arrowScrollImpl(direction);
            if (handled) {
                playSoundEffect(SoundEffectConstants.getContantForFocusDirection(direction));
            }
            return handled;
        } finally {
            mInLayout = false;
        }
    }

    
Used by arrowScrollImpl(int) to help determine the next selected position to move to. This return a position in the direction given if the selected item is fully visible. 
Params:
selectedView – Current selected view to move from
selectedPos – Current selected position to move from
direction – Direction to move in
Returns:
Desired selected position after moving in the given direction/**
     * Used by {@link #arrowScrollImpl(int)} to help determine the next selected position
     * to move to. This return a position in the direction given if the selected item
     * is fully visible.
     *
     * @param selectedView Current selected view to move from
     * @param selectedPos Current selected position to move from
     * @param direction Direction to move in
     * @return Desired selected position after moving in the given direction
     */
    private final int nextSelectedPositionForDirection(
            View selectedView, int selectedPos, int direction) {
        int nextSelected;

        if (direction == View.FOCUS_DOWN) {
            final int listBottom = getHeight() - mListPadding.bottom;
            if (selectedView != null && selectedView.getBottom() <= listBottom) {
                nextSelected = selectedPos != INVALID_POSITION && selectedPos >= mFirstPosition ?
                        selectedPos + 1 :
                        mFirstPosition;
            } else {
                return INVALID_POSITION;
            }
        } else {
            final int listTop = mListPadding.top;
            if (selectedView != null && selectedView.getTop() >= listTop) {
                final int lastPos = mFirstPosition + getChildCount() - 1;
                nextSelected = selectedPos != INVALID_POSITION && selectedPos <= lastPos ?
                        selectedPos - 1 :
                        lastPos;
            } else {
                return INVALID_POSITION;
            }
        }

        if (nextSelected < 0 || nextSelected >= mAdapter.getCount()) {
            return INVALID_POSITION;
        }
        return lookForSelectablePosition(nextSelected, direction == View.FOCUS_DOWN);
    }

    
Handle an arrow scroll going up or down.  Take into account whether items are selectable,
whether there are focusable items etc.
Params:
direction – Either View.FOCUS_UP or View.FOCUS_DOWN.
Returns:
Whether any scrolling, selection or focus change occured./**
     * Handle an arrow scroll going up or down.  Take into account whether items are selectable,
     * whether there are focusable items etc.
     *
     * @param direction Either {@link android.view.View#FOCUS_UP} or {@link android.view.View#FOCUS_DOWN}.
     * @return Whether any scrolling, selection or focus change occured.
     */
    private boolean arrowScrollImpl(int direction) {
        if (getChildCount() <= 0) {
            return false;
        }

        View selectedView = getSelectedView();
        int selectedPos = mSelectedPosition;

        int nextSelectedPosition = nextSelectedPositionForDirection(selectedView, selectedPos, direction);
        int amountToScroll = amountToScroll(direction, nextSelectedPosition);

        // if we are moving focus, we may OVERRIDE the default behavior
        final ArrowScrollFocusResult focusResult = mItemsCanFocus ? arrowScrollFocused(direction) : null;
        if (focusResult != null) {
            nextSelectedPosition = focusResult.getSelectedPosition();
            amountToScroll = focusResult.getAmountToScroll();
        }

        boolean needToRedraw = focusResult != null;
        if (nextSelectedPosition != INVALID_POSITION) {
            handleNewSelectionChange(selectedView, direction, nextSelectedPosition, focusResult != null);
            setSelectedPositionInt(nextSelectedPosition);
            setNextSelectedPositionInt(nextSelectedPosition);
            selectedView = getSelectedView();
            selectedPos = nextSelectedPosition;
            if (mItemsCanFocus && focusResult == null) {
                // there was no new view found to take focus, make sure we
                // don't leave focus with the old selection
                final View focused = getFocusedChild();
                if (focused != null) {
                    focused.clearFocus();
                }
            }
            needToRedraw = true;
            checkSelectionChanged();
        }

        if (amountToScroll > 0) {
            scrollListItemsBy((direction == View.FOCUS_UP) ? amountToScroll : -amountToScroll);
            needToRedraw = true;
        }

        // if we didn't find a new focusable, make sure any existing focused
        // item that was panned off screen gives up focus.
        if (mItemsCanFocus && (focusResult == null)
                && selectedView != null && selectedView.hasFocus()) {
            final View focused = selectedView.findFocus();
            if (focused != null) {
                if (!isViewAncestorOf(focused, this) || distanceToView(focused) > 0) {
                    focused.clearFocus();
                }
            }
        }

        // if  the current selection is panned off, we need to remove the selection
        if (nextSelectedPosition == INVALID_POSITION && selectedView != null
                && !isViewAncestorOf(selectedView, this)) {
            selectedView = null;
            hideSelector();

            // but we don't want to set the ressurect position (that would make subsequent
            // unhandled key events bring back the item we just scrolled off!)
            mResurrectToPosition = INVALID_POSITION;
        }

        if (needToRedraw) {
            if (selectedView != null) {
                positionSelectorLikeFocus(selectedPos, selectedView);
                mSelectedTop = selectedView.getTop();
            }
            if (!awakenScrollBars()) {
                invalidate();
            }
            invokeOnItemScrollListener();
            return true;
        }

        return false;
    }

    
When selection changes, it is possible that the previously selected or the
next selected item will change its size.  If so, we need to offset some folks,
and re-layout the items as appropriate.
Params:
selectedView – The currently selected view (before changing selection).
  should be null if there was no previous selection.
direction – Either View.FOCUS_UP or View.FOCUS_DOWN.
newSelectedPosition – The position of the next selection.
newFocusAssigned – whether new focus was assigned.  This matters because
       when something has focus, we don't want to show selection (ugh)./**
     * When selection changes, it is possible that the previously selected or the
     * next selected item will change its size.  If so, we need to offset some folks,
     * and re-layout the items as appropriate.
     *
     * @param selectedView The currently selected view (before changing selection).
     *   should be <code>null</code> if there was no previous selection.
     * @param direction Either {@link android.view.View#FOCUS_UP} or
     *        {@link android.view.View#FOCUS_DOWN}.
     * @param newSelectedPosition The position of the next selection.
     * @param newFocusAssigned whether new focus was assigned.  This matters because
     *        when something has focus, we don't want to show selection (ugh).
     */
    private void handleNewSelectionChange(View selectedView, int direction, int newSelectedPosition,
            boolean newFocusAssigned) {
        if (newSelectedPosition == INVALID_POSITION) {
            throw new IllegalArgumentException("newSelectedPosition needs to be valid");
        }

        // whether or not we are moving down or up, we want to preserve the
        // top of whatever view is on top:
        // - moving down: the view that had selection
        // - moving up: the view that is getting selection
        View topView;
        View bottomView;
        int topViewIndex, bottomViewIndex;
        boolean topSelected = false;
        final int selectedIndex = mSelectedPosition - mFirstPosition;
        final int nextSelectedIndex = newSelectedPosition - mFirstPosition;
        if (direction == View.FOCUS_UP) {
            topViewIndex = nextSelectedIndex;
            bottomViewIndex = selectedIndex;
            topView = getChildAt(topViewIndex);
            bottomView = selectedView;
            topSelected = true;
        } else {
            topViewIndex = selectedIndex;
            bottomViewIndex = nextSelectedIndex;
            topView = selectedView;
            bottomView = getChildAt(bottomViewIndex);
        }

        final int numChildren = getChildCount();

        // start with top view: is it changing size?
        if (topView != null) {
            topView.setSelected(!newFocusAssigned && topSelected);
            measureAndAdjustDown(topView, topViewIndex, numChildren);
        }

        // is the bottom view changing size?
        if (bottomView != null) {
            bottomView.setSelected(!newFocusAssigned && !topSelected);
            measureAndAdjustDown(bottomView, bottomViewIndex, numChildren);
        }
    }

    
Re-measure a child, and if its height changes, lay it out preserving its
top, and adjust the children below it appropriately.
Params:
child – The child
childIndex – The view group index of the child.
numChildren – The number of children in the view group./**
     * Re-measure a child, and if its height changes, lay it out preserving its
     * top, and adjust the children below it appropriately.
     * @param child The child
     * @param childIndex The view group index of the child.
     * @param numChildren The number of children in the view group.
     */
    private void measureAndAdjustDown(View child, int childIndex, int numChildren) {
        int oldHeight = child.getHeight();
        measureItem(child);
        if (child.getMeasuredHeight() != oldHeight) {
            // lay out the view, preserving its top
            relayoutMeasuredItem(child);

            // adjust views below appropriately
            final int heightDelta = child.getMeasuredHeight() - oldHeight;
            for (int i = childIndex + 1; i < numChildren; i++) {
                getChildAt(i).offsetTopAndBottom(heightDelta);
            }
        }
    }

    
Measure a particular list child.
TODO: unify with setUpChild.
Params:
child – The child./**
     * Measure a particular list child.
     * TODO: unify with setUpChild.
     * @param child The child.
     */
    private void measureItem(View child) {
        ViewGroup.LayoutParams p = child.getLayoutParams();
        if (p == null) {
            p = new ViewGroup.LayoutParams(
                    ViewGroup.LayoutParams.MATCH_PARENT,
                    ViewGroup.LayoutParams.WRAP_CONTENT);
        }

        int childWidthSpec = ViewGroup.getChildMeasureSpec(mWidthMeasureSpec,
                mListPadding.left + mListPadding.right, p.width);
        int lpHeight = p.height;
        int childHeightSpec;
        if (lpHeight > 0) {
            childHeightSpec = MeasureSpec.makeMeasureSpec(lpHeight, MeasureSpec.EXACTLY);
        } else {
            childHeightSpec = MeasureSpec.makeSafeMeasureSpec(getMeasuredHeight(),
                    MeasureSpec.UNSPECIFIED);
        }
        child.measure(childWidthSpec, childHeightSpec);
    }

    
Layout a child that has been measured, preserving its top position.
TODO: unify with setUpChild.
Params:
child – The child./**
     * Layout a child that has been measured, preserving its top position.
     * TODO: unify with setUpChild.
     * @param child The child.
     */
    private void relayoutMeasuredItem(View child) {
        final int w = child.getMeasuredWidth();
        final int h = child.getMeasuredHeight();
        final int childLeft = mListPadding.left;
        final int childRight = childLeft + w;
        final int childTop = child.getTop();
        final int childBottom = childTop + h;
        child.layout(childLeft, childTop, childRight, childBottom);
    }

    
Returns:
The amount to preview next items when arrow srolling./**
     * @return The amount to preview next items when arrow srolling.
     */
    private int getArrowScrollPreviewLength() {
        return Math.max(MIN_SCROLL_PREVIEW_PIXELS, getVerticalFadingEdgeLength());
    }

    
Determine how much we need to scroll in order to get the next selected view visible, with a fading edge showing below as applicable. The amount is capped at getMaxScrollAmount() . 
Params:
direction – either View.FOCUS_UP or View.FOCUS_DOWN.
nextSelectedPosition – The position of the next selection, or AdapterView<ListAdapter>.INVALID_POSITION if there is no next selectable position
Returns:
The amount to scroll. Note: this is always positive!  Direction
        needs to be taken into account when actually scrolling./**
     * Determine how much we need to scroll in order to get the next selected view
     * visible, with a fading edge showing below as applicable.  The amount is
     * capped at {@link #getMaxScrollAmount()} .
     *
     * @param direction either {@link android.view.View#FOCUS_UP} or
     *        {@link android.view.View#FOCUS_DOWN}.
     * @param nextSelectedPosition The position of the next selection, or
     *        {@link #INVALID_POSITION} if there is no next selectable position
     * @return The amount to scroll. Note: this is always positive!  Direction
     *         needs to be taken into account when actually scrolling.
     */
    private int amountToScroll(int direction, int nextSelectedPosition) {
        final int listBottom = getHeight() - mListPadding.bottom;
        final int listTop = mListPadding.top;

        int numChildren = getChildCount();

        if (direction == View.FOCUS_DOWN) {
            int indexToMakeVisible = numChildren - 1;
            if (nextSelectedPosition != INVALID_POSITION) {
                indexToMakeVisible = nextSelectedPosition - mFirstPosition;
            }
            while (numChildren <= indexToMakeVisible) {
                // Child to view is not attached yet.
                addViewBelow(getChildAt(numChildren - 1), mFirstPosition + numChildren - 1);
                numChildren++;
            }
            final int positionToMakeVisible = mFirstPosition + indexToMakeVisible;
            final View viewToMakeVisible = getChildAt(indexToMakeVisible);

            int goalBottom = listBottom;
            if (positionToMakeVisible < mItemCount - 1) {
                goalBottom -= getArrowScrollPreviewLength();
            }

            if (viewToMakeVisible.getBottom() <= goalBottom) {
                // item is fully visible.
                return 0;
            }

            if (nextSelectedPosition != INVALID_POSITION
                    && (goalBottom - viewToMakeVisible.getTop()) >= getMaxScrollAmount()) {
                // item already has enough of it visible, changing selection is good enough
                return 0;
            }

            int amountToScroll = (viewToMakeVisible.getBottom() - goalBottom);

            if ((mFirstPosition + numChildren) == mItemCount) {
                // last is last in list -> make sure we don't scroll past it
                final int max = getChildAt(numChildren - 1).getBottom() - listBottom;
                amountToScroll = Math.min(amountToScroll, max);
            }

            return Math.min(amountToScroll, getMaxScrollAmount());
        } else {
            int indexToMakeVisible = 0;
            if (nextSelectedPosition != INVALID_POSITION) {
                indexToMakeVisible = nextSelectedPosition - mFirstPosition;
            }
            while (indexToMakeVisible < 0) {
                // Child to view is not attached yet.
                addViewAbove(getChildAt(0), mFirstPosition);
                mFirstPosition--;
                indexToMakeVisible = nextSelectedPosition - mFirstPosition;
            }
            final int positionToMakeVisible = mFirstPosition + indexToMakeVisible;
            final View viewToMakeVisible = getChildAt(indexToMakeVisible);
            int goalTop = listTop;
            if (positionToMakeVisible > 0) {
                goalTop += getArrowScrollPreviewLength();
            }
            if (viewToMakeVisible.getTop() >= goalTop) {
                // item is fully visible.
                return 0;
            }

            if (nextSelectedPosition != INVALID_POSITION &&
                    (viewToMakeVisible.getBottom() - goalTop) >= getMaxScrollAmount()) {
                // item already has enough of it visible, changing selection is good enough
                return 0;
            }

            int amountToScroll = (goalTop - viewToMakeVisible.getTop());
            if (mFirstPosition == 0) {
                // first is first in list -> make sure we don't scroll past it
                final int max = listTop - getChildAt(0).getTop();
                amountToScroll = Math.min(amountToScroll,  max);
            }
            return Math.min(amountToScroll, getMaxScrollAmount());
        }
    }

    
Holds results of focus aware arrow scrolling.
/**
     * Holds results of focus aware arrow scrolling.
     */
    static private class ArrowScrollFocusResult {
        private int mSelectedPosition;
        private int mAmountToScroll;

        
How ListView.arrowScrollFocused returns its values. /**
         * How {@link android.widget.ListView#arrowScrollFocused} returns its values.
         */
        void populate(int selectedPosition, int amountToScroll) {
            mSelectedPosition = selectedPosition;
            mAmountToScroll = amountToScroll;
        }

        public int getSelectedPosition() {
            return mSelectedPosition;
        }

        public int getAmountToScroll() {
            return mAmountToScroll;
        }
    }

    
Params:
direction – either View.FOCUS_UP or View.FOCUS_DOWN.
Returns:
The position of the next selectable position of the views that are currently visible, taking into account the fact that there might be no selection. Returns AdapterView<ListAdapter>.INVALID_POSITION if there is no selectable view on screen in the given direction./**
     * @param direction either {@link android.view.View#FOCUS_UP} or
     *        {@link android.view.View#FOCUS_DOWN}.
     * @return The position of the next selectable position of the views that
     *         are currently visible, taking into account the fact that there might
     *         be no selection.  Returns {@link #INVALID_POSITION} if there is no
     *         selectable view on screen in the given direction.
     */
    private int lookForSelectablePositionOnScreen(int direction) {
        final int firstPosition = mFirstPosition;
        if (direction == View.FOCUS_DOWN) {
            int startPos = (mSelectedPosition != INVALID_POSITION) ?
                    mSelectedPosition + 1 :
                    firstPosition;
            if (startPos >= mAdapter.getCount()) {
                return INVALID_POSITION;
            }
            if (startPos < firstPosition) {
                startPos = firstPosition;
            }

            final int lastVisiblePos = getLastVisiblePosition();
            final ListAdapter adapter = getAdapter();
            for (int pos = startPos; pos <= lastVisiblePos; pos++) {
                if (adapter.isEnabled(pos)
                        && getChildAt(pos - firstPosition).getVisibility() == View.VISIBLE) {
                    return pos;
                }
            }
        } else {
            int last = firstPosition + getChildCount() - 1;
            int startPos = (mSelectedPosition != INVALID_POSITION) ?
                    mSelectedPosition - 1 :
                    firstPosition + getChildCount() - 1;
            if (startPos < 0 || startPos >= mAdapter.getCount()) {
                return INVALID_POSITION;
            }
            if (startPos > last) {
                startPos = last;
            }

            final ListAdapter adapter = getAdapter();
            for (int pos = startPos; pos >= firstPosition; pos--) {
                if (adapter.isEnabled(pos)
                        && getChildAt(pos - firstPosition).getVisibility() == View.VISIBLE) {
                    return pos;
                }
            }
        }
        return INVALID_POSITION;
    }

    
Do an arrow scroll based on focus searching. If a new view is given focus, return the selection delta and amount to scroll via an ArrowScrollFocusResult, otherwise, return null. 
Params:
direction – either View.FOCUS_UP or View.FOCUS_DOWN.
Returns:
The result if focus has changed, or null./**
     * Do an arrow scroll based on focus searching.  If a new view is
     * given focus, return the selection delta and amount to scroll via
     * an {@link ArrowScrollFocusResult}, otherwise, return null.
     *
     * @param direction either {@link android.view.View#FOCUS_UP} or
     *        {@link android.view.View#FOCUS_DOWN}.
     * @return The result if focus has changed, or <code>null</code>.
     */
    private ArrowScrollFocusResult arrowScrollFocused(final int direction) {
        final View selectedView = getSelectedView();
        View newFocus;
        if (selectedView != null && selectedView.hasFocus()) {
            View oldFocus = selectedView.findFocus();
            newFocus = FocusFinder.getInstance().findNextFocus(this, oldFocus, direction);
        } else {
            if (direction == View.FOCUS_DOWN) {
                final boolean topFadingEdgeShowing = (mFirstPosition > 0);
                final int listTop = mListPadding.top +
                        (topFadingEdgeShowing ? getArrowScrollPreviewLength() : 0);
                final int ySearchPoint =
                        (selectedView != null && selectedView.getTop() > listTop) ?
                                selectedView.getTop() :
                                listTop;
                mTempRect.set(0, ySearchPoint, 0, ySearchPoint);
            } else {
                final boolean bottomFadingEdgeShowing =
                        (mFirstPosition + getChildCount() - 1) < mItemCount;
                final int listBottom = getHeight() - mListPadding.bottom -
                        (bottomFadingEdgeShowing ? getArrowScrollPreviewLength() : 0);
                final int ySearchPoint =
                        (selectedView != null && selectedView.getBottom() < listBottom) ?
                                selectedView.getBottom() :
                                listBottom;
                mTempRect.set(0, ySearchPoint, 0, ySearchPoint);
            }
            newFocus = FocusFinder.getInstance().findNextFocusFromRect(this, mTempRect, direction);
        }

        if (newFocus != null) {
            final int positionOfNewFocus = positionOfNewFocus(newFocus);

            // if the focus change is in a different new position, make sure
            // we aren't jumping over another selectable position
            if (mSelectedPosition != INVALID_POSITION && positionOfNewFocus != mSelectedPosition) {
                final int selectablePosition = lookForSelectablePositionOnScreen(direction);
                if (selectablePosition != INVALID_POSITION &&
                        ((direction == View.FOCUS_DOWN && selectablePosition < positionOfNewFocus) ||
                        (direction == View.FOCUS_UP && selectablePosition > positionOfNewFocus))) {
                    return null;
                }
            }

            int focusScroll = amountToScrollToNewFocus(direction, newFocus, positionOfNewFocus);

            final int maxScrollAmount = getMaxScrollAmount();
            if (focusScroll < maxScrollAmount) {
                // not moving too far, safe to give next view focus
                newFocus.requestFocus(direction);
                mArrowScrollFocusResult.populate(positionOfNewFocus, focusScroll);
                return mArrowScrollFocusResult;
            } else if (distanceToView(newFocus) < maxScrollAmount){
                // Case to consider:
                // too far to get entire next focusable on screen, but by going
                // max scroll amount, we are getting it at least partially in view,
                // so give it focus and scroll the max ammount.
                newFocus.requestFocus(direction);
                mArrowScrollFocusResult.populate(positionOfNewFocus, maxScrollAmount);
                return mArrowScrollFocusResult;
            }
        }
        return null;
    }

    
Params:
newFocus – The view that would have focus.
Returns:
the position that contains newFocus/**
     * @param newFocus The view that would have focus.
     * @return the position that contains newFocus
     */
    private int positionOfNewFocus(View newFocus) {
        final int numChildren = getChildCount();
        for (int i = 0; i < numChildren; i++) {
            final View child = getChildAt(i);
            if (isViewAncestorOf(newFocus, child)) {
                return mFirstPosition + i;
            }
        }
        throw new IllegalArgumentException("newFocus is not a child of any of the"
                + " children of the list!");
    }

    
Return true if child is an ancestor of parent, (or equal to the parent).
/**
     * Return true if child is an ancestor of parent, (or equal to the parent).
     */
    private boolean isViewAncestorOf(View child, View parent) {
        if (child == parent) {
            return true;
        }

        final ViewParent theParent = child.getParent();
        return (theParent instanceof ViewGroup) && isViewAncestorOf((View) theParent, parent);
    }

    
Determine how much we need to scroll in order to get newFocus in view.
Params:
direction – either View.FOCUS_UP or View.FOCUS_DOWN.
newFocus – The view that would take focus.
positionOfNewFocus – The position of the list item containing newFocus
Returns:
The amount to scroll.  Note: this is always positive!  Direction
  needs to be taken into account when actually scrolling./**
     * Determine how much we need to scroll in order to get newFocus in view.
     * @param direction either {@link android.view.View#FOCUS_UP} or
     *        {@link android.view.View#FOCUS_DOWN}.
     * @param newFocus The view that would take focus.
     * @param positionOfNewFocus The position of the list item containing newFocus
     * @return The amount to scroll.  Note: this is always positive!  Direction
     *   needs to be taken into account when actually scrolling.
     */
    private int amountToScrollToNewFocus(int direction, View newFocus, int positionOfNewFocus) {
        int amountToScroll = 0;
        newFocus.getDrawingRect(mTempRect);
        offsetDescendantRectToMyCoords(newFocus, mTempRect);
        if (direction == View.FOCUS_UP) {
            if (mTempRect.top < mListPadding.top) {
                amountToScroll = mListPadding.top - mTempRect.top;
                if (positionOfNewFocus > 0) {
                    amountToScroll += getArrowScrollPreviewLength();
                }
            }
        } else {
            final int listBottom = getHeight() - mListPadding.bottom;
            if (mTempRect.bottom > listBottom) {
                amountToScroll = mTempRect.bottom - listBottom;
                if (positionOfNewFocus < mItemCount - 1) {
                    amountToScroll += getArrowScrollPreviewLength();
                }
            }
        }
        return amountToScroll;
    }

    
Determine the distance to the nearest edge of a view in a particular
direction.
Params:
descendant – A descendant of this list.
Returns:
The distance, or 0 if the nearest edge is already on screen./**
     * Determine the distance to the nearest edge of a view in a particular
     * direction.
     *
     * @param descendant A descendant of this list.
     * @return The distance, or 0 if the nearest edge is already on screen.
     */
    private int distanceToView(View descendant) {
        int distance = 0;
        descendant.getDrawingRect(mTempRect);
        offsetDescendantRectToMyCoords(descendant, mTempRect);
        final int listBottom = mBottom - mTop - mListPadding.bottom;
        if (mTempRect.bottom < mListPadding.top) {
            distance = mListPadding.top - mTempRect.bottom;
        } else if (mTempRect.top > listBottom) {
            distance = mTempRect.top - listBottom;
        }
        return distance;
    }


    
Scroll the children by amount, adding a view at the end and removing
views that fall off as necessary.
Params:
amount – The amount (positive or negative) to scroll./**
     * Scroll the children by amount, adding a view at the end and removing
     * views that fall off as necessary.
     *
     * @param amount The amount (positive or negative) to scroll.
     */
    private void scrollListItemsBy(int amount) {
        offsetChildrenTopAndBottom(amount);

        final int listBottom = getHeight() - mListPadding.bottom;
        final int listTop = mListPadding.top;
        final AbsListView.RecycleBin recycleBin = mRecycler;

        if (amount < 0) {
            // shifted items up

            // may need to pan views into the bottom space
            int numChildren = getChildCount();
            View last = getChildAt(numChildren - 1);
            while (last.getBottom() < listBottom) {
                final int lastVisiblePosition = mFirstPosition + numChildren - 1;
                if (lastVisiblePosition < mItemCount - 1) {
                    last = addViewBelow(last, lastVisiblePosition);
                    numChildren++;
                } else {
                    break;
                }
            }

            // may have brought in the last child of the list that is skinnier
            // than the fading edge, thereby leaving space at the end.  need
            // to shift back
            if (last.getBottom() < listBottom) {
                offsetChildrenTopAndBottom(listBottom - last.getBottom());
            }

            // top views may be panned off screen
            View first = getChildAt(0);
            while (first.getBottom() < listTop) {
                AbsListView.LayoutParams layoutParams = (LayoutParams) first.getLayoutParams();
                if (recycleBin.shouldRecycleViewType(layoutParams.viewType)) {
                    recycleBin.addScrapView(first, mFirstPosition);
                }
                detachViewFromParent(first);
                first = getChildAt(0);
                mFirstPosition++;
            }
        } else {
            // shifted items down
            View first = getChildAt(0);

            // may need to pan views into top
            while ((first.getTop() > listTop) && (mFirstPosition > 0)) {
                first = addViewAbove(first, mFirstPosition);
                mFirstPosition--;
            }

            // may have brought the very first child of the list in too far and
            // need to shift it back
            if (first.getTop() > listTop) {
                offsetChildrenTopAndBottom(listTop - first.getTop());
            }

            int lastIndex = getChildCount() - 1;
            View last = getChildAt(lastIndex);

            // bottom view may be panned off screen
            while (last.getTop() > listBottom) {
                AbsListView.LayoutParams layoutParams = (LayoutParams) last.getLayoutParams();
                if (recycleBin.shouldRecycleViewType(layoutParams.viewType)) {
                    recycleBin.addScrapView(last, mFirstPosition+lastIndex);
                }
                detachViewFromParent(last);
                last = getChildAt(--lastIndex);
            }
        }
        recycleBin.fullyDetachScrapViews();
        removeUnusedFixedViews(mHeaderViewInfos);
        removeUnusedFixedViews(mFooterViewInfos);
    }

    private View addViewAbove(View theView, int position) {
        int abovePosition = position - 1;
        View view = obtainView(abovePosition, mIsScrap);
        int edgeOfNewChild = theView.getTop() - mDividerHeight;
        setupChild(view, abovePosition, edgeOfNewChild, false, mListPadding.left,
                false, mIsScrap[0]);
        return view;
    }

    private View addViewBelow(View theView, int position) {
        int belowPosition = position + 1;
        View view = obtainView(belowPosition, mIsScrap);
        int edgeOfNewChild = theView.getBottom() + mDividerHeight;
        setupChild(view, belowPosition, edgeOfNewChild, true, mListPadding.left,
                false, mIsScrap[0]);
        return view;
    }

    
Indicates that the views created by the ListAdapter can contain focusable
items.
Params:
itemsCanFocus – true if items can get focus, false otherwise/**
     * Indicates that the views created by the ListAdapter can contain focusable
     * items.
     *
     * @param itemsCanFocus true if items can get focus, false otherwise
     */
    public void setItemsCanFocus(boolean itemsCanFocus) {
        mItemsCanFocus = itemsCanFocus;
        if (!itemsCanFocus) {
            setDescendantFocusability(ViewGroup.FOCUS_BLOCK_DESCENDANTS);
        }
    }

    
Returns:
Whether the views created by the ListAdapter can contain focusable
items./**
     * @return Whether the views created by the ListAdapter can contain focusable
     * items.
     */
    public boolean getItemsCanFocus() {
        return mItemsCanFocus;
    }

    @Override
    public boolean isOpaque() {
        boolean retValue = (mCachingActive && mIsCacheColorOpaque && mDividerIsOpaque &&
                hasOpaqueScrollbars()) || super.isOpaque();
        if (retValue) {
            // only return true if the list items cover the entire area of the view
            final int listTop = mListPadding != null ? mListPadding.top : mPaddingTop;
            View first = getChildAt(0);
            if (first == null || first.getTop() > listTop) {
                return false;
            }
            final int listBottom = getHeight() -
                    (mListPadding != null ? mListPadding.bottom : mPaddingBottom);
            View last = getChildAt(getChildCount() - 1);
            if (last == null || last.getBottom() < listBottom) {
                return false;
            }
        }
        return retValue;
    }

    @Override
    public void setCacheColorHint(int color) {
        final boolean opaque = (color >>> 24) == 0xFF;
        mIsCacheColorOpaque = opaque;
        if (opaque) {
            if (mDividerPaint == null) {
                mDividerPaint = new Paint();
            }
            mDividerPaint.setColor(color);
        }
        super.setCacheColorHint(color);
    }

    void drawOverscrollHeader(Canvas canvas, Drawable drawable, Rect bounds) {
        final int height = drawable.getMinimumHeight();

        canvas.save();
        canvas.clipRect(bounds);

        final int span = bounds.bottom - bounds.top;
        if (span < height) {
            bounds.top = bounds.bottom - height;
        }

        drawable.setBounds(bounds);
        drawable.draw(canvas);

        canvas.restore();
    }

    void drawOverscrollFooter(Canvas canvas, Drawable drawable, Rect bounds) {
        final int height = drawable.getMinimumHeight();

        canvas.save();
        canvas.clipRect(bounds);

        final int span = bounds.bottom - bounds.top;
        if (span < height) {
            bounds.bottom = bounds.top + height;
        }

        drawable.setBounds(bounds);
        drawable.draw(canvas);

        canvas.restore();
    }

    @Override
    protected void dispatchDraw(Canvas canvas) {
        if (mCachingStarted) {
            mCachingActive = true;
        }

        // Draw the dividers
        final int dividerHeight = mDividerHeight;
        final Drawable overscrollHeader = mOverScrollHeader;
        final Drawable overscrollFooter = mOverScrollFooter;
        final boolean drawOverscrollHeader = overscrollHeader != null;
        final boolean drawOverscrollFooter = overscrollFooter != null;
        final boolean drawDividers = dividerHeight > 0 && mDivider != null;

        if (drawDividers || drawOverscrollHeader || drawOverscrollFooter) {
            // Only modify the top and bottom in the loop, we set the left and right here
            final Rect bounds = mTempRect;
            bounds.left = mPaddingLeft;
            bounds.right = mRight - mLeft - mPaddingRight;

            final int count = getChildCount();
            final int headerCount = getHeaderViewsCount();
            final int itemCount = mItemCount;
            final int footerLimit = (itemCount - mFooterViewInfos.size());
            final boolean headerDividers = mHeaderDividersEnabled;
            final boolean footerDividers = mFooterDividersEnabled;
            final int first = mFirstPosition;
            final boolean areAllItemsSelectable = mAreAllItemsSelectable;
            final ListAdapter adapter = mAdapter;
            // If the list is opaque *and* the background is not, we want to
            // fill a rect where the dividers would be for non-selectable items
            // If the list is opaque and the background is also opaque, we don't
            // need to draw anything since the background will do it for us
            final boolean fillForMissingDividers = isOpaque() && !super.isOpaque();

            if (fillForMissingDividers && mDividerPaint == null && mIsCacheColorOpaque) {
                mDividerPaint = new Paint();
                mDividerPaint.setColor(getCacheColorHint());
            }
            final Paint paint = mDividerPaint;

            int effectivePaddingTop = 0;
            int effectivePaddingBottom = 0;
            if ((mGroupFlags & CLIP_TO_PADDING_MASK) == CLIP_TO_PADDING_MASK) {
                effectivePaddingTop = mListPadding.top;
                effectivePaddingBottom = mListPadding.bottom;
            }

            final int listBottom = mBottom - mTop - effectivePaddingBottom + mScrollY;
            if (!mStackFromBottom) {
                int bottom = 0;

                // Draw top divider or header for overscroll
                final int scrollY = mScrollY;
                if (count > 0 && scrollY < 0) {
                    if (drawOverscrollHeader) {
                        bounds.bottom = 0;
                        bounds.top = scrollY;
                        drawOverscrollHeader(canvas, overscrollHeader, bounds);
                    } else if (drawDividers) {
                        bounds.bottom = 0;
                        bounds.top = -dividerHeight;
                        drawDivider(canvas, bounds, -1);
                    }
                }

                for (int i = 0; i < count; i++) {
                    final int itemIndex = (first + i);
                    final boolean isHeader = (itemIndex < headerCount);
                    final boolean isFooter = (itemIndex >= footerLimit);
                    if ((headerDividers || !isHeader) && (footerDividers || !isFooter)) {
                        final View child = getChildAt(i);
                        bottom = child.getBottom();
                        final boolean isLastItem = (i == (count - 1));

                        if (drawDividers && (bottom < listBottom)
                                && !(drawOverscrollFooter && isLastItem)) {
                            final int nextIndex = (itemIndex + 1);
                            // Draw dividers between enabled items, headers
                            // and/or footers when enabled and requested, and
                            // after the last enabled item.
                            if (adapter.isEnabled(itemIndex) && (headerDividers || !isHeader
                                    && (nextIndex >= headerCount)) && (isLastItem
                                    || adapter.isEnabled(nextIndex) && (footerDividers || !isFooter
                                            && (nextIndex < footerLimit)))) {
                                bounds.top = bottom;
                                bounds.bottom = bottom + dividerHeight;
                                drawDivider(canvas, bounds, i);
                            } else if (fillForMissingDividers) {
                                bounds.top = bottom;
                                bounds.bottom = bottom + dividerHeight;
                                canvas.drawRect(bounds, paint);
                            }
                        }
                    }
                }

                final int overFooterBottom = mBottom + mScrollY;
                if (drawOverscrollFooter && first + count == itemCount &&
                        overFooterBottom > bottom) {
                    bounds.top = bottom;
                    bounds.bottom = overFooterBottom;
                    drawOverscrollFooter(canvas, overscrollFooter, bounds);
                }
            } else {
                int top;

                final int scrollY = mScrollY;

                if (count > 0 && drawOverscrollHeader) {
                    bounds.top = scrollY;
                    bounds.bottom = getChildAt(0).getTop();
                    drawOverscrollHeader(canvas, overscrollHeader, bounds);
                }

                final int start = drawOverscrollHeader ? 1 : 0;
                for (int i = start; i < count; i++) {
                    final int itemIndex = (first + i);
                    final boolean isHeader = (itemIndex < headerCount);
                    final boolean isFooter = (itemIndex >= footerLimit);
                    if ((headerDividers || !isHeader) && (footerDividers || !isFooter)) {
                        final View child = getChildAt(i);
                        top = child.getTop();
                        if (drawDividers && (top > effectivePaddingTop)) {
                            final boolean isFirstItem = (i == start);
                            final int previousIndex = (itemIndex - 1);
                            // Draw dividers between enabled items, headers
                            // and/or footers when enabled and requested, and
                            // before the first enabled item.
                            if (adapter.isEnabled(itemIndex) && (headerDividers || !isHeader
                                    && (previousIndex >= headerCount)) && (isFirstItem ||
                                    adapter.isEnabled(previousIndex) && (footerDividers || !isFooter
                                            && (previousIndex < footerLimit)))) {
                                bounds.top = top - dividerHeight;
                                bounds.bottom = top;
                                // Give the method the child ABOVE the divider,
                                // so we subtract one from our child position.
                                // Give -1 when there is no child above the
                                // divider.
                                drawDivider(canvas, bounds, i - 1);
                            } else if (fillForMissingDividers) {
                                bounds.top = top - dividerHeight;
                                bounds.bottom = top;
                                canvas.drawRect(bounds, paint);
                            }
                        }
                    }
                }

                if (count > 0 && scrollY > 0) {
                    if (drawOverscrollFooter) {
                        final int absListBottom = mBottom;
                        bounds.top = absListBottom;
                        bounds.bottom = absListBottom + scrollY;
                        drawOverscrollFooter(canvas, overscrollFooter, bounds);
                    } else if (drawDividers) {
                        bounds.top = listBottom;
                        bounds.bottom = listBottom + dividerHeight;
                        drawDivider(canvas, bounds, -1);
                    }
                }
            }
        }

        // Draw the indicators (these should be drawn above the dividers) and children
        super.dispatchDraw(canvas);
    }

    @Override
    protected boolean drawChild(Canvas canvas, View child, long drawingTime) {
        boolean more = super.drawChild(canvas, child, drawingTime);
        if (mCachingActive && child.mCachingFailed) {
            mCachingActive = false;
        }
        return more;
    }

    
Draws a divider for the given child in the given bounds.
Params:
canvas – The canvas to draw to.
bounds – The bounds of the divider.
childIndex – The index of child (of the View) above the divider.
           This will be -1 if there is no child above the divider to be
           drawn./**
     * Draws a divider for the given child in the given bounds.
     *
     * @param canvas The canvas to draw to.
     * @param bounds The bounds of the divider.
     * @param childIndex The index of child (of the View) above the divider.
     *            This will be -1 if there is no child above the divider to be
     *            drawn.
     */
    void drawDivider(Canvas canvas, Rect bounds, int childIndex) {
        // This widget draws the same divider for all children
        final Drawable divider = mDivider;

        divider.setBounds(bounds);
        divider.draw(canvas);
    }

    
Returns the drawable that will be drawn between each item in the list.
Returns:
the current drawable drawn between list elements
@attr
ref R.styleable#ListView_divider/**
     * Returns the drawable that will be drawn between each item in the list.
     *
     * @return the current drawable drawn between list elements
     * @attr ref R.styleable#ListView_divider
     */
    @Nullable
    public Drawable getDivider() {
        return mDivider;
    }

    
Sets the drawable that will be drawn between each item in the list.

Note: If the drawable does not have an intrinsic height, you should also call setDividerHeight(int). 
Params:
divider – the drawable to use
@attr
ref R.styleable#ListView_divider/**
     * Sets the drawable that will be drawn between each item in the list.
     * <p>
     * <strong>Note:</strong> If the drawable does not have an intrinsic
     * height, you should also call {@link #setDividerHeight(int)}.
     *
     * @param divider the drawable to use
     * @attr ref R.styleable#ListView_divider
     */
    public void setDivider(@Nullable Drawable divider) {
        if (divider != null) {
            mDividerHeight = divider.getIntrinsicHeight();
        } else {
            mDividerHeight = 0;
        }
        mDivider = divider;
        mDividerIsOpaque = divider == null || divider.getOpacity() == PixelFormat.OPAQUE;
        requestLayout();
        invalidate();
    }

    
Returns:
Returns the height of the divider that will be drawn between each item in the list./**
     * @return Returns the height of the divider that will be drawn between each item in the list.
     */
    public int getDividerHeight() {
        return mDividerHeight;
    }

    
Sets the height of the divider that will be drawn between each item in the list. Calling this will override the intrinsic height as set by setDivider(Drawable) 
Params:
height – The new height of the divider in pixels./**
     * Sets the height of the divider that will be drawn between each item in the list. Calling
     * this will override the intrinsic height as set by {@link #setDivider(Drawable)}
     *
     * @param height The new height of the divider in pixels.
     */
    public void setDividerHeight(int height) {
        mDividerHeight = height;
        requestLayout();
        invalidate();
    }

    
Enables or disables the drawing of the divider for header views.
Params:
headerDividersEnabled – True to draw the headers, false otherwise.
See Also:
setFooterDividersEnabled(boolean)
areHeaderDividersEnabled()
addHeaderView(View)/**
     * Enables or disables the drawing of the divider for header views.
     *
     * @param headerDividersEnabled True to draw the headers, false otherwise.
     *
     * @see #setFooterDividersEnabled(boolean)
     * @see #areHeaderDividersEnabled()
     * @see #addHeaderView(android.view.View)
     */
    public void setHeaderDividersEnabled(boolean headerDividersEnabled) {
        mHeaderDividersEnabled = headerDividersEnabled;
        invalidate();
    }

    
See Also:
setHeaderDividersEnabled(boolean)
Returns:
Whether the drawing of the divider for header views is enabled/**
     * @return Whether the drawing of the divider for header views is enabled
     *
     * @see #setHeaderDividersEnabled(boolean)
     */
    public boolean areHeaderDividersEnabled() {
        return mHeaderDividersEnabled;
    }

    
Enables or disables the drawing of the divider for footer views.
Params:
footerDividersEnabled – True to draw the footers, false otherwise.
See Also:
setHeaderDividersEnabled(boolean)
areFooterDividersEnabled()
addFooterView(View)/**
     * Enables or disables the drawing of the divider for footer views.
     *
     * @param footerDividersEnabled True to draw the footers, false otherwise.
     *
     * @see #setHeaderDividersEnabled(boolean)
     * @see #areFooterDividersEnabled()
     * @see #addFooterView(android.view.View)
     */
    public void setFooterDividersEnabled(boolean footerDividersEnabled) {
        mFooterDividersEnabled = footerDividersEnabled;
        invalidate();
    }

    
See Also:
setFooterDividersEnabled(boolean)
Returns:
Whether the drawing of the divider for footer views is enabled/**
     * @return Whether the drawing of the divider for footer views is enabled
     *
     * @see #setFooterDividersEnabled(boolean)
     */
    public boolean areFooterDividersEnabled() {
        return mFooterDividersEnabled;
    }

    
Sets the drawable that will be drawn above all other list content.
This area can become visible when the user overscrolls the list.
Params:
header – The drawable to use/**
     * Sets the drawable that will be drawn above all other list content.
     * This area can become visible when the user overscrolls the list.
     *
     * @param header The drawable to use
     */
    public void setOverscrollHeader(Drawable header) {
        mOverScrollHeader = header;
        if (mScrollY < 0) {
            invalidate();
        }
    }

    
Returns:
The drawable that will be drawn above all other list content/**
     * @return The drawable that will be drawn above all other list content
     */
    public Drawable getOverscrollHeader() {
        return mOverScrollHeader;
    }

    
Sets the drawable that will be drawn below all other list content.
This area can become visible when the user overscrolls the list,
or when the list's content does not fully fill the container area.
Params:
footer – The drawable to use/**
     * Sets the drawable that will be drawn below all other list content.
     * This area can become visible when the user overscrolls the list,
     * or when the list's content does not fully fill the container area.
     *
     * @param footer The drawable to use
     */
    public void setOverscrollFooter(Drawable footer) {
        mOverScrollFooter = footer;
        invalidate();
    }

    
Returns:
The drawable that will be drawn below all other list content/**
     * @return The drawable that will be drawn below all other list content
     */
    public Drawable getOverscrollFooter() {
        return mOverScrollFooter;
    }

    @Override
    protected void onFocusChanged(boolean gainFocus, int direction, Rect previouslyFocusedRect) {
        super.onFocusChanged(gainFocus, direction, previouslyFocusedRect);

        final ListAdapter adapter = mAdapter;
        int closetChildIndex = -1;
        int closestChildTop = 0;
        if (adapter != null && gainFocus && previouslyFocusedRect != null) {
            previouslyFocusedRect.offset(mScrollX, mScrollY);

            // Don't cache the result of getChildCount or mFirstPosition here,
            // it could change in layoutChildren.
            if (adapter.getCount() < getChildCount() + mFirstPosition) {
                mLayoutMode = LAYOUT_NORMAL;
                layoutChildren();
            }

            // figure out which item should be selected based on previously
            // focused rect
            Rect otherRect = mTempRect;
            int minDistance = Integer.MAX_VALUE;
            final int childCount = getChildCount();
            final int firstPosition = mFirstPosition;

            for (int i = 0; i < childCount; i++) {
                // only consider selectable views
                if (!adapter.isEnabled(firstPosition + i)) {
                    continue;
                }

                View other = getChildAt(i);
                other.getDrawingRect(otherRect);
                offsetDescendantRectToMyCoords(other, otherRect);
                int distance = getDistance(previouslyFocusedRect, otherRect, direction);

                if (distance < minDistance) {
                    minDistance = distance;
                    closetChildIndex = i;
                    closestChildTop = other.getTop();
                }
            }
        }

        if (closetChildIndex >= 0) {
            setSelectionFromTop(closetChildIndex + mFirstPosition, closestChildTop);
        } else {
            requestLayout();
        }
    }


    /*
     * (non-Javadoc)
     *
     * Children specified in XML are assumed to be header views. After we have
     * parsed them move them out of the children list and into mHeaderViews.
     */
    @Override
    protected void onFinishInflate() {
        super.onFinishInflate();

        int count = getChildCount();
        if (count > 0) {
            for (int i = 0; i < count; ++i) {
                addHeaderView(getChildAt(i));
            }
            removeAllViews();
        }
    }

    
See Also:
findViewById.findViewById(int)
@removed
For internal use only. This should have been hidden./**
     * @see android.view.View#findViewById(int)
     * @removed For internal use only. This should have been hidden.
     */
    @Override
    protected <T extends View> T findViewTraversal(@IdRes int id) {
        // First look in our children, then in any header and footer views that
        // may be scrolled off.
        View v = super.findViewTraversal(id);
        if (v == null) {
            v = findViewInHeadersOrFooters(mHeaderViewInfos, id);
            if (v != null) {
                return (T) v;
            }
            v = findViewInHeadersOrFooters(mFooterViewInfos, id);
            if (v != null) {
                return (T) v;
            }
        }
        return (T) v;
    }

    View findViewInHeadersOrFooters(ArrayList<FixedViewInfo> where, int id) {
        // Look in the passed in list of headers or footers for the view.
        if (where != null) {
            int len = where.size();
            View v;

            for (int i = 0; i < len; i++) {
                v = where.get(i).view;

                if (!v.isRootNamespace()) {
                    v = v.findViewById(id);

                    if (v != null) {
                        return v;
                    }
                }
            }
        }
        return null;
    }

    
See Also:
findViewWithTag.findViewWithTag(Object)
@removed
For internal use only. This should have been hidden./**
     * @see android.view.View#findViewWithTag(Object)
     * @removed For internal use only. This should have been hidden.
     */
    @Override
    protected <T extends View> T findViewWithTagTraversal(Object tag) {
        // First look in our children, then in any header and footer views that
        // may be scrolled off.
        View v = super.findViewWithTagTraversal(tag);
        if (v == null) {
            v = findViewWithTagInHeadersOrFooters(mHeaderViewInfos, tag);
            if (v != null) {
                return (T) v;
            }

            v = findViewWithTagInHeadersOrFooters(mFooterViewInfos, tag);
            if (v != null) {
                return (T) v;
            }
        }
        return (T) v;
    }

    View findViewWithTagInHeadersOrFooters(ArrayList<FixedViewInfo> where, Object tag) {
        // Look in the passed in list of headers or footers for the view with
        // the tag.
        if (where != null) {
            int len = where.size();
            View v;

            for (int i = 0; i < len; i++) {
                v = where.get(i).view;

                if (!v.isRootNamespace()) {
                    v = v.findViewWithTag(tag);

                    if (v != null) {
                        return v;
                    }
                }
            }
        }
        return null;
    }

    
First look in our children, then in any header and footer views that may
be scrolled off.
See Also:
findViewByPredicate.findViewByPredicate(Predicate)
@hide
/**
     * First look in our children, then in any header and footer views that may
     * be scrolled off.
     *
     * @see android.view.View#findViewByPredicate(Predicate)
     * @hide
     */
    @Override
    protected <T extends View> T findViewByPredicateTraversal(
            Predicate<View> predicate, View childToSkip) {
        View v = super.findViewByPredicateTraversal(predicate, childToSkip);
        if (v == null) {
            v = findViewByPredicateInHeadersOrFooters(mHeaderViewInfos, predicate, childToSkip);
            if (v != null) {
                return (T) v;
            }

            v = findViewByPredicateInHeadersOrFooters(mFooterViewInfos, predicate, childToSkip);
            if (v != null) {
                return (T) v;
            }
        }
        return (T) v;
    }

    
Look in the passed in list of headers or footers for the first view that
matches the predicate.
/**
     * Look in the passed in list of headers or footers for the first view that
     * matches the predicate.
     */
    View findViewByPredicateInHeadersOrFooters(ArrayList<FixedViewInfo> where,
            Predicate<View> predicate, View childToSkip) {
        if (where != null) {
            int len = where.size();
            View v;

            for (int i = 0; i < len; i++) {
                v = where.get(i).view;

                if (v != childToSkip && !v.isRootNamespace()) {
                    v = v.findViewByPredicate(predicate);

                    if (v != null) {
                        return v;
                    }
                }
            }
        }
        return null;
    }

    
Returns the set of checked items ids. The result is only valid if the choice mode has not been set to AbsListView.CHOICE_MODE_NONE. 
Returns:
A new array which contains the id of each checked item in the
        list.
Deprecated:
Use AbsListView.getCheckedItemIds() instead./**
     * Returns the set of checked items ids. The result is only valid if the
     * choice mode has not been set to {@link #CHOICE_MODE_NONE}.
     *
     * @return A new array which contains the id of each checked item in the
     *         list.
     *
     * @deprecated Use {@link #getCheckedItemIds()} instead.
     */
    @Deprecated
    public long[] getCheckItemIds() {
        // Use new behavior that correctly handles stable ID mapping.
        if (mAdapter != null && mAdapter.hasStableIds()) {
            return getCheckedItemIds();
        }

        // Old behavior was buggy, but would sort of work for adapters without stable IDs.
        // Fall back to it to support legacy apps.
        if (mChoiceMode != CHOICE_MODE_NONE && mCheckStates != null && mAdapter != null) {
            final SparseBooleanArray states = mCheckStates;
            final int count = states.size();
            final long[] ids = new long[count];
            final ListAdapter adapter = mAdapter;

            int checkedCount = 0;
            for (int i = 0; i < count; i++) {
                if (states.valueAt(i)) {
                    ids[checkedCount++] = adapter.getItemId(states.keyAt(i));
                }
            }

            // Trim array if needed. mCheckStates may contain false values
            // resulting in checkedCount being smaller than count.
            if (checkedCount == count) {
                return ids;
            } else {
                final long[] result = new long[checkedCount];
                System.arraycopy(ids, 0, result, 0, checkedCount);

                return result;
            }
        }
        return new long[0];
    }

    @Override
    int getHeightForPosition(int position) {
        final int height = super.getHeightForPosition(position);
        if (shouldAdjustHeightForDivider(position)) {
            return height + mDividerHeight;
        }
        return height;
    }

    private boolean shouldAdjustHeightForDivider(int itemIndex) {
        final int dividerHeight = mDividerHeight;
        final Drawable overscrollHeader = mOverScrollHeader;
        final Drawable overscrollFooter = mOverScrollFooter;
        final boolean drawOverscrollHeader = overscrollHeader != null;
        final boolean drawOverscrollFooter = overscrollFooter != null;
        final boolean drawDividers = dividerHeight > 0 && mDivider != null;

        if (drawDividers) {
            final boolean fillForMissingDividers = isOpaque() && !super.isOpaque();
            final int itemCount = mItemCount;
            final int headerCount = getHeaderViewsCount();
            final int footerLimit = (itemCount - mFooterViewInfos.size());
            final boolean isHeader = (itemIndex < headerCount);
            final boolean isFooter = (itemIndex >= footerLimit);
            final boolean headerDividers = mHeaderDividersEnabled;
            final boolean footerDividers = mFooterDividersEnabled;
            if ((headerDividers || !isHeader) && (footerDividers || !isFooter)) {
                final ListAdapter adapter = mAdapter;
                if (!mStackFromBottom) {
                    final boolean isLastItem = (itemIndex == (itemCount - 1));
                    if (!drawOverscrollFooter || !isLastItem) {
                        final int nextIndex = itemIndex + 1;
                        // Draw dividers between enabled items, headers
                        // and/or footers when enabled and requested, and
                        // after the last enabled item.
                        if (adapter.isEnabled(itemIndex) && (headerDividers || !isHeader
                                && (nextIndex >= headerCount)) && (isLastItem
                                || adapter.isEnabled(nextIndex) && (footerDividers || !isFooter
                                                && (nextIndex < footerLimit)))) {
                            return true;
                        } else if (fillForMissingDividers) {
                            return true;
                        }
                    }
                } else {
                    final int start = drawOverscrollHeader ? 1 : 0;
                    final boolean isFirstItem = (itemIndex == start);
                    if (!isFirstItem) {
                        final int previousIndex = (itemIndex - 1);
                        // Draw dividers between enabled items, headers
                        // and/or footers when enabled and requested, and
                        // before the first enabled item.
                        if (adapter.isEnabled(itemIndex) && (headerDividers || !isHeader
                                && (previousIndex >= headerCount)) && (isFirstItem ||
                                adapter.isEnabled(previousIndex) && (footerDividers || !isFooter
                                        && (previousIndex < footerLimit)))) {
                            return true;
                        } else if (fillForMissingDividers) {
                            return true;
                        }
                    }
                }
            }
        }

        return false;
    }

    @Override
    public CharSequence getAccessibilityClassName() {
        return ListView.class.getName();
    }

    
@hide
/** @hide */
    @Override
    public void onInitializeAccessibilityNodeInfoInternal(AccessibilityNodeInfo info) {
        super.onInitializeAccessibilityNodeInfoInternal(info);

        final int rowsCount = getCount();
        final int selectionMode = getSelectionModeForAccessibility();
        final CollectionInfo collectionInfo = CollectionInfo.obtain(
                rowsCount, 1, false, selectionMode);
        info.setCollectionInfo(collectionInfo);

        if (rowsCount > 0) {
            info.addAction(AccessibilityAction.ACTION_SCROLL_TO_POSITION);
        }
    }

    
@hide
/** @hide */
    @Override
    public boolean performAccessibilityActionInternal(int action, Bundle arguments) {
        if (super.performAccessibilityActionInternal(action, arguments)) {
            return true;
        }

        switch (action) {
            case R.id.accessibilityActionScrollToPosition: {
                final int row = arguments.getInt(AccessibilityNodeInfo.ACTION_ARGUMENT_ROW_INT, -1);
                final int position = Math.min(row, getCount() - 1);
                if (row >= 0) {
                    // The accessibility service gets data asynchronously, so
                    // we'll be a little lenient by clamping the last position.
                    smoothScrollToPosition(position);
                    return true;
                }
            } break;
        }

        return false;
    }

    @Override
    public void onInitializeAccessibilityNodeInfoForItem(
            View view, int position, AccessibilityNodeInfo info) {
        super.onInitializeAccessibilityNodeInfoForItem(view, position, info);

        final LayoutParams lp = (LayoutParams) view.getLayoutParams();
        final boolean isHeading = lp != null && lp.viewType == ITEM_VIEW_TYPE_HEADER_OR_FOOTER;
        final boolean isSelected = isItemChecked(position);
        final CollectionItemInfo itemInfo = CollectionItemInfo.obtain(
                position, 1, 0, 1, isHeading, isSelected);
        info.setCollectionItemInfo(itemInfo);
    }

    
@hide
/** @hide */
    @Override
    protected void encodeProperties(@NonNull ViewHierarchyEncoder encoder) {
        super.encodeProperties(encoder);

        encoder.addProperty("recycleOnMeasure", recycleOnMeasure());
    }

    
@hide
/** @hide */
    protected HeaderViewListAdapter wrapHeaderListAdapterInternal(
            ArrayList<ListView.FixedViewInfo> headerViewInfos,
            ArrayList<ListView.FixedViewInfo> footerViewInfos,
            ListAdapter adapter) {
        return new HeaderViewListAdapter(headerViewInfos, footerViewInfos, adapter);
    }

    
@hide
/** @hide */
    protected void wrapHeaderListAdapterInternal() {
        mAdapter = wrapHeaderListAdapterInternal(mHeaderViewInfos, mFooterViewInfos, mAdapter);
    }

    
@hide
/** @hide */
    protected void dispatchDataSetObserverOnChangedInternal() {
        if (mDataSetObserver != null) {
            mDataSetObserver.onChanged();
        }
    }
}