android/android-9.0.0_r35 : android/widget/Spinner.java

Spinner
https://source.android.com/
/*
 * Copyright (C) 2007 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.DrawableRes;
import android.annotation.Nullable;
import android.annotation.TestApi;
import android.annotation.Widget;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.DialogInterface.OnClickListener;
import android.content.res.Resources;
import android.content.res.Resources.Theme;
import android.content.res.TypedArray;
import android.database.DataSetObserver;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.os.Build;
import android.os.Parcel;
import android.os.Parcelable;
import android.util.AttributeSet;
import android.util.Log;
import android.view.ContextThemeWrapper;
import android.view.Gravity;
import android.view.MotionEvent;
import android.view.PointerIcon;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewTreeObserver;
import android.view.ViewTreeObserver.OnGlobalLayoutListener;
import android.view.accessibility.AccessibilityNodeInfo;
import android.widget.PopupWindow.OnDismissListener;

import com.android.internal.R;
import com.android.internal.view.menu.ShowableListMenu;

A view that displays one child at a time and lets the user pick among them. The items in the Spinner come from the Adapter associated with this view. See the Spinners guide.
@attr ref android.R.styleable#Spinner_dropDownSelector
@attr ref android.R.styleable#Spinner_dropDownWidth
@attr ref android.R.styleable#Spinner_gravity
@attr ref android.R.styleable#Spinner_popupBackground
@attr ref android.R.styleable#Spinner_prompt
@attr ref android.R.styleable#Spinner_spinnerMode
@attr ref android.R.styleable#ListPopupWindow_dropDownVerticalOffset
@attr ref android.R.styleable#ListPopupWindow_dropDownHorizontalOffset/**
 * A view that displays one child at a time and lets the user pick among them.
 * The items in the Spinner come from the {@link Adapter} associated with
 * this view.
 *
 * <p>See the <a href="{@docRoot}guide/topics/ui/controls/spinner.html">Spinners</a> guide.</p>
 *
 * @attr ref android.R.styleable#Spinner_dropDownSelector
 * @attr ref android.R.styleable#Spinner_dropDownWidth
 * @attr ref android.R.styleable#Spinner_gravity
 * @attr ref android.R.styleable#Spinner_popupBackground
 * @attr ref android.R.styleable#Spinner_prompt
 * @attr ref android.R.styleable#Spinner_spinnerMode
 * @attr ref android.R.styleable#ListPopupWindow_dropDownVerticalOffset
 * @attr ref android.R.styleable#ListPopupWindow_dropDownHorizontalOffset
 */
@Widget
public class Spinner extends AbsSpinner implements OnClickListener {
    private static final String TAG = "Spinner";

    // Only measure this many items to get a decent max width.
    private static final int MAX_ITEMS_MEASURED = 15;

    Use a dialog window for selecting spinner options.
/**
     * Use a dialog window for selecting spinner options.
     */
    public static final int MODE_DIALOG = 0;

    Use a dropdown anchored to the Spinner for selecting spinner options.
/**
     * Use a dropdown anchored to the Spinner for selecting spinner options.
     */
    public static final int MODE_DROPDOWN = 1;

    Use the theme-supplied value to select the dropdown mode.
/**
     * Use the theme-supplied value to select the dropdown mode.
     */
    private static final int MODE_THEME = -1;

    private final Rect mTempRect = new Rect();

    Context used to inflate the popup window or dialog. /** Context used to inflate the popup window or dialog. */
    private final Context mPopupContext;

    Forwarding listener used to implement drag-to-open. /** Forwarding listener used to implement drag-to-open. */
    private ForwardingListener mForwardingListener;

    Temporary holder for setAdapter() calls from the super constructor. /** Temporary holder for setAdapter() calls from the super constructor. */
    private SpinnerAdapter mTempAdapter;

    private SpinnerPopup mPopup;
    int mDropDownWidth;

    private int mGravity;
    private boolean mDisableChildrenWhenDisabled;

    Constructs a new spinner with the given context's theme.
Params: context – The Context the view is running in, through which it can
               access the current theme, resources, etc./**
     * Constructs a new spinner with the given context's theme.
     *
     * @param context The Context the view is running in, through which it can
     *                access the current theme, resources, etc.
     */
    public Spinner(Context context) {
        this(context, null);
    }

    Constructs a new spinner with the given context's theme and the supplied
mode of displaying choices. mode may be one of MODE_DIALOG or MODE_DROPDOWN. 
Params: context – The Context the view is running in, through which it can
               access the current theme, resources, etc.
mode – Constant describing how the user will select choices from
            the spinner.
See Also: MODE_DIALOG
MODE_DROPDOWN/**
     * Constructs a new spinner with the given context's theme and the supplied
     * mode of displaying choices. <code>mode</code> may be one of
     * {@link #MODE_DIALOG} or {@link #MODE_DROPDOWN}.
     *
     * @param context The Context the view is running in, through which it can
     *                access the current theme, resources, etc.
     * @param mode Constant describing how the user will select choices from
     *             the spinner.
     *
     * @see #MODE_DIALOG
     * @see #MODE_DROPDOWN
     */
    public Spinner(Context context, int mode) {
        this(context, null, com.android.internal.R.attr.spinnerStyle, mode);
    }

    Constructs a new spinner with the given context's theme and the supplied
attribute set.
Params: context – The Context the view is running in, through which it can
               access the current theme, resources, etc.
attrs – The attributes of the XML tag that is inflating the view./**
     * Constructs a new spinner with the given context's theme and the supplied
     * attribute set.
     *
     * @param context The Context the view is running in, through which it can
     *                access the current theme, resources, etc.
     * @param attrs The attributes of the XML tag that is inflating the view.
     */
    public Spinner(Context context, AttributeSet attrs) {
        this(context, attrs, com.android.internal.R.attr.spinnerStyle);
    }

    Constructs a new spinner with the given context's theme, the supplied
attribute set, and default style attribute.
Params: context – The Context the view is running in, through which it can
               access the current theme, resources, etc.
attrs – The attributes of the XML tag that is inflating the view.
defStyleAttr – An attribute in the current theme that contains a
                    reference to a style resource that supplies default
                    values for the view. Can be 0 to not look for
                    defaults./**
     * Constructs a new spinner with the given context's theme, the supplied
     * attribute set, and default style attribute.
     *
     * @param context The Context the view is running in, through which it can
     *                access the current theme, resources, etc.
     * @param attrs The attributes of the XML tag that is inflating the view.
     * @param defStyleAttr An attribute in the current theme that contains a
     *                     reference to a style resource that supplies default
     *                     values for the view. Can be 0 to not look for
     *                     defaults.
     */
    public Spinner(Context context, AttributeSet attrs, int defStyleAttr) {
        this(context, attrs, defStyleAttr, 0, MODE_THEME);
    }

    Constructs a new spinner with the given context's theme, the supplied
attribute set, and default style attribute. mode may be one of MODE_DIALOG or MODE_DROPDOWN and determines how the user will select choices from the spinner. 
Params: context – The Context the view is running in, through which it can
               access the current theme, resources, etc.
attrs – The attributes of the XML tag that is inflating the view.
defStyleAttr – An attribute in the current theme that contains a
                    reference to a style resource that supplies default
                    values for the view. Can be 0 to not look for defaults.
mode – Constant describing how the user will select choices from the
            spinner.
See Also: MODE_DIALOG
MODE_DROPDOWN/**
     * Constructs a new spinner with the given context's theme, the supplied
     * attribute set, and default style attribute. <code>mode</code> may be one
     * of {@link #MODE_DIALOG} or {@link #MODE_DROPDOWN} and determines how the
     * user will select choices from the spinner.
     *
     * @param context The Context the view is running in, through which it can
     *                access the current theme, resources, etc.
     * @param attrs The attributes of the XML tag that is inflating the view.
     * @param defStyleAttr An attribute in the current theme that contains a
     *                     reference to a style resource that supplies default
     *                     values for the view. Can be 0 to not look for defaults.
     * @param mode Constant describing how the user will select choices from the
     *             spinner.
     *
     * @see #MODE_DIALOG
     * @see #MODE_DROPDOWN
     */
    public Spinner(Context context, AttributeSet attrs, int defStyleAttr, int mode) {
        this(context, attrs, defStyleAttr, 0, mode);
    }

    Constructs a new spinner with the given context's theme, the supplied
attribute set, and default styles. mode may be one of MODE_DIALOG or MODE_DROPDOWN and determines how the user will select choices from the spinner. 
Params: context – The Context the view is running in, through which it can
               access the current theme, resources, etc.
attrs – The attributes of the XML tag that is inflating the view.
defStyleAttr – An attribute in the current theme that contains a
                    reference to a style resource that supplies default
                    values for the view. Can be 0 to not look for
                    defaults.
defStyleRes – A resource identifier of a style resource that
                   supplies default values for the view, used only if
                   defStyleAttr is 0 or can not be found in the theme.
                   Can be 0 to not look for defaults.
mode – Constant describing how the user will select choices from
            the spinner.
See Also: MODE_DIALOG
MODE_DROPDOWN/**
     * Constructs a new spinner with the given context's theme, the supplied
     * attribute set, and default styles. <code>mode</code> may be one of
     * {@link #MODE_DIALOG} or {@link #MODE_DROPDOWN} and determines how the
     * user will select choices from the spinner.
     *
     * @param context The Context the view is running in, through which it can
     *                access the current theme, resources, etc.
     * @param attrs The attributes of the XML tag that is inflating the view.
     * @param defStyleAttr An attribute in the current theme that contains a
     *                     reference to a style resource that supplies default
     *                     values for the view. Can be 0 to not look for
     *                     defaults.
     * @param defStyleRes A resource identifier of a style resource that
     *                    supplies default values for the view, used only if
     *                    defStyleAttr is 0 or can not be found in the theme.
     *                    Can be 0 to not look for defaults.
     * @param mode Constant describing how the user will select choices from
     *             the spinner.
     *
     * @see #MODE_DIALOG
     * @see #MODE_DROPDOWN
     */
    public Spinner(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes,
            int mode) {
        this(context, attrs, defStyleAttr, defStyleRes, mode, null);
    }

    Constructs a new spinner with the given context, the supplied attribute set, default styles, popup mode (one of MODE_DIALOG or MODE_DROPDOWN), and the theme against which the popup should be inflated. 
Params: context – The context against which the view is inflated, which
               provides access to the current theme, resources, etc.
attrs – The attributes of the XML tag that is inflating the view.
defStyleAttr – An attribute in the current theme that contains a
                    reference to a style resource that supplies default
                    values for the view. Can be 0 to not look for
                    defaults.
defStyleRes – A resource identifier of a style resource that
                   supplies default values for the view, used only if
                   defStyleAttr is 0 or can not be found in the theme.
                   Can be 0 to not look for defaults.
mode – Constant describing how the user will select choices from
            the spinner.
popupTheme – The theme against which the dialog or dropdown popup should be inflated. May be null to use the view theme. If set, this will override any value specified by Spinner_popupTheme.Spinner_popupTheme.
See Also: MODE_DIALOG
MODE_DROPDOWN/**
     * Constructs a new spinner with the given context, the supplied attribute
     * set, default styles, popup mode (one of {@link #MODE_DIALOG} or
     * {@link #MODE_DROPDOWN}), and the theme against which the popup should be
     * inflated.
     *
     * @param context The context against which the view is inflated, which
     *                provides access to the current theme, resources, etc.
     * @param attrs The attributes of the XML tag that is inflating the view.
     * @param defStyleAttr An attribute in the current theme that contains a
     *                     reference to a style resource that supplies default
     *                     values for the view. Can be 0 to not look for
     *                     defaults.
     * @param defStyleRes A resource identifier of a style resource that
     *                    supplies default values for the view, used only if
     *                    defStyleAttr is 0 or can not be found in the theme.
     *                    Can be 0 to not look for defaults.
     * @param mode Constant describing how the user will select choices from
     *             the spinner.
     * @param popupTheme The theme against which the dialog or dropdown popup
     *                   should be inflated. May be {@code null} to use the
     *                   view theme. If set, this will override any value
     *                   specified by
     *                   {@link android.R.styleable#Spinner_popupTheme}.
     *
     * @see #MODE_DIALOG
     * @see #MODE_DROPDOWN
     */
    public Spinner(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes, int mode,
            Theme popupTheme) {
        super(context, attrs, defStyleAttr, defStyleRes);

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

        if (popupTheme != null) {
            mPopupContext = new ContextThemeWrapper(context, popupTheme);
        } else {
            final int popupThemeResId = a.getResourceId(R.styleable.Spinner_popupTheme, 0);
            if (popupThemeResId != 0) {
                mPopupContext = new ContextThemeWrapper(context, popupThemeResId);
            } else {
                mPopupContext = context;
            }
        }

        if (mode == MODE_THEME) {
            mode = a.getInt(R.styleable.Spinner_spinnerMode, MODE_DIALOG);
        }

        switch (mode) {
            case MODE_DIALOG: {
                mPopup = new DialogPopup();
                mPopup.setPromptText(a.getString(R.styleable.Spinner_prompt));
                break;
            }

            case MODE_DROPDOWN: {
                final DropdownPopup popup = new DropdownPopup(
                        mPopupContext, attrs, defStyleAttr, defStyleRes);
                final TypedArray pa = mPopupContext.obtainStyledAttributes(
                        attrs, R.styleable.Spinner, defStyleAttr, defStyleRes);
                mDropDownWidth = pa.getLayoutDimension(R.styleable.Spinner_dropDownWidth,
                        ViewGroup.LayoutParams.WRAP_CONTENT);
                if (pa.hasValueOrEmpty(R.styleable.Spinner_dropDownSelector)) {
                    popup.setListSelector(pa.getDrawable(
                            R.styleable.Spinner_dropDownSelector));
                }
                popup.setBackgroundDrawable(pa.getDrawable(R.styleable.Spinner_popupBackground));
                popup.setPromptText(a.getString(R.styleable.Spinner_prompt));
                pa.recycle();

                mPopup = popup;
                mForwardingListener = new ForwardingListener(this) {
                    @Override
                    public ShowableListMenu getPopup() {
                        return popup;
                    }

                    @Override
                    public boolean onForwardingStarted() {
                        if (!mPopup.isShowing()) {
                            mPopup.show(getTextDirection(), getTextAlignment());
                        }
                        return true;
                    }
                };
                break;
            }
        }

        mGravity = a.getInt(R.styleable.Spinner_gravity, Gravity.CENTER);
        mDisableChildrenWhenDisabled = a.getBoolean(
                R.styleable.Spinner_disableChildrenWhenDisabled, false);

        a.recycle();

        // Base constructor can call setAdapter before we initialize mPopup.
        // Finish setting things up if this happened.
        if (mTempAdapter != null) {
            setAdapter(mTempAdapter);
            mTempAdapter = null;
        }
    }

    Returns: the context used to inflate the Spinner's popup or dialog window/**
     * @return the context used to inflate the Spinner's popup or dialog window
     */
    public Context getPopupContext() {
        return mPopupContext;
    }

    Set the background drawable for the spinner's popup window of choices. Only valid in MODE_DROPDOWN; this method is a no-op in other modes. 
Params: background – Background drawable
@attr ref android.R.styleable#Spinner_popupBackground/**
     * Set the background drawable for the spinner's popup window of choices.
     * Only valid in {@link #MODE_DROPDOWN}; this method is a no-op in other modes.
     *
     * @param background Background drawable
     *
     * @attr ref android.R.styleable#Spinner_popupBackground
     */
    public void setPopupBackgroundDrawable(Drawable background) {
        if (!(mPopup instanceof DropdownPopup)) {
            Log.e(TAG, "setPopupBackgroundDrawable: incompatible spinner mode; ignoring...");
            return;
        }
        mPopup.setBackgroundDrawable(background);
    }

    Set the background drawable for the spinner's popup window of choices. Only valid in MODE_DROPDOWN; this method is a no-op in other modes. 
Params: resId – Resource ID of a background drawable
@attr ref android.R.styleable#Spinner_popupBackground/**
     * Set the background drawable for the spinner's popup window of choices.
     * Only valid in {@link #MODE_DROPDOWN}; this method is a no-op in other modes.
     *
     * @param resId Resource ID of a background drawable
     *
     * @attr ref android.R.styleable#Spinner_popupBackground
     */
    public void setPopupBackgroundResource(@DrawableRes int resId) {
        setPopupBackgroundDrawable(getPopupContext().getDrawable(resId));
    }

    Get the background drawable for the spinner's popup window of choices. Only valid in MODE_DROPDOWN; other modes will return null. 
Returns: background Background drawable
@attr ref android.R.styleable#Spinner_popupBackground/**
     * Get the background drawable for the spinner's popup window of choices.
     * Only valid in {@link #MODE_DROPDOWN}; other modes will return null.
     *
     * @return background Background drawable
     *
     * @attr ref android.R.styleable#Spinner_popupBackground
     */
    public Drawable getPopupBackground() {
        return mPopup.getBackground();
    }

    @hide /**
     * @hide
     */
    @TestApi
    public boolean isPopupShowing() {
        return (mPopup != null) && mPopup.isShowing();
    }

    Set a vertical offset in pixels for the spinner's popup window of choices. Only valid in MODE_DROPDOWN; this method is a no-op in other modes. 
Params: pixels – Vertical offset in pixels
@attr ref android.R.styleable#ListPopupWindow_dropDownVerticalOffset/**
     * Set a vertical offset in pixels for the spinner's popup window of choices.
     * Only valid in {@link #MODE_DROPDOWN}; this method is a no-op in other modes.
     *
     * @param pixels Vertical offset in pixels
     *
     * @attr ref android.R.styleable#ListPopupWindow_dropDownVerticalOffset
     */
    public void setDropDownVerticalOffset(int pixels) {
        mPopup.setVerticalOffset(pixels);
    }

    Get the configured vertical offset in pixels for the spinner's popup window of choices. Only valid in MODE_DROPDOWN; other modes will return 0. 
Returns: Vertical offset in pixels
@attr ref android.R.styleable#ListPopupWindow_dropDownVerticalOffset/**
     * Get the configured vertical offset in pixels for the spinner's popup window of choices.
     * Only valid in {@link #MODE_DROPDOWN}; other modes will return 0.
     *
     * @return Vertical offset in pixels
     *
     * @attr ref android.R.styleable#ListPopupWindow_dropDownVerticalOffset
     */
    public int getDropDownVerticalOffset() {
        return mPopup.getVerticalOffset();
    }

    Set a horizontal offset in pixels for the spinner's popup window of choices. Only valid in MODE_DROPDOWN; this method is a no-op in other modes. 
Params: pixels – Horizontal offset in pixels
@attr ref android.R.styleable#ListPopupWindow_dropDownHorizontalOffset/**
     * Set a horizontal offset in pixels for the spinner's popup window of choices.
     * Only valid in {@link #MODE_DROPDOWN}; this method is a no-op in other modes.
     *
     * @param pixels Horizontal offset in pixels
     *
     * @attr ref android.R.styleable#ListPopupWindow_dropDownHorizontalOffset
     */
    public void setDropDownHorizontalOffset(int pixels) {
        mPopup.setHorizontalOffset(pixels);
    }

    Get the configured horizontal offset in pixels for the spinner's popup window of choices. Only valid in MODE_DROPDOWN; other modes will return 0. 
Returns: Horizontal offset in pixels
@attr ref android.R.styleable#ListPopupWindow_dropDownHorizontalOffset/**
     * Get the configured horizontal offset in pixels for the spinner's popup window of choices.
     * Only valid in {@link #MODE_DROPDOWN}; other modes will return 0.
     *
     * @return Horizontal offset in pixels
     *
     * @attr ref android.R.styleable#ListPopupWindow_dropDownHorizontalOffset
     */
    public int getDropDownHorizontalOffset() {
        return mPopup.getHorizontalOffset();
    }

    Set the width of the spinner's popup window of choices in pixels. This value may also be set to LayoutParams.MATCH_PARENT to match the width of the Spinner itself, or LayoutParams.WRAP_CONTENT to wrap to the measured size of contained dropdown list items. Only valid in MODE_DROPDOWN; this method is a no-op in other modes.
Params: pixels – Width in pixels, WRAP_CONTENT, or MATCH_PARENT
@attr ref android.R.styleable#Spinner_dropDownWidth/**
     * Set the width of the spinner's popup window of choices in pixels. This value
     * may also be set to {@link android.view.ViewGroup.LayoutParams#MATCH_PARENT}
     * to match the width of the Spinner itself, or
     * {@link android.view.ViewGroup.LayoutParams#WRAP_CONTENT} to wrap to the measured size
     * of contained dropdown list items.
     *
     * <p>Only valid in {@link #MODE_DROPDOWN}; this method is a no-op in other modes.</p>
     *
     * @param pixels Width in pixels, WRAP_CONTENT, or MATCH_PARENT
     *
     * @attr ref android.R.styleable#Spinner_dropDownWidth
     */
    public void setDropDownWidth(int pixels) {
        if (!(mPopup instanceof DropdownPopup)) {
            Log.e(TAG, "Cannot set dropdown width for MODE_DIALOG, ignoring");
            return;
        }
        mDropDownWidth = pixels;
    }

    Get the configured width of the spinner's popup window of choices in pixels. The returned value may also be LayoutParams.MATCH_PARENT meaning the popup window will match the width of the Spinner itself, or LayoutParams.WRAP_CONTENT to wrap to the measured size of contained dropdown list items. 
Returns: Width in pixels, WRAP_CONTENT, or MATCH_PARENT
@attr ref android.R.styleable#Spinner_dropDownWidth/**
     * Get the configured width of the spinner's popup window of choices in pixels.
     * The returned value may also be {@link android.view.ViewGroup.LayoutParams#MATCH_PARENT}
     * meaning the popup window will match the width of the Spinner itself, or
     * {@link android.view.ViewGroup.LayoutParams#WRAP_CONTENT} to wrap to the measured size
     * of contained dropdown list items.
     *
     * @return Width in pixels, WRAP_CONTENT, or MATCH_PARENT
     *
     * @attr ref android.R.styleable#Spinner_dropDownWidth
     */
    public int getDropDownWidth() {
        return mDropDownWidth;
    }

    @Override
    public void setEnabled(boolean enabled) {
        super.setEnabled(enabled);
        if (mDisableChildrenWhenDisabled) {
            final int count = getChildCount();
            for (int i = 0; i < count; i++) {
                getChildAt(i).setEnabled(enabled);
            }
        }
    }

    Describes how the selected item view is positioned. Currently only the horizontal component
is used. The default is determined by the current theme.
Params: gravity – See Gravity
@attr ref android.R.styleable#Spinner_gravity/**
     * Describes how the selected item view is positioned. Currently only the horizontal component
     * is used. The default is determined by the current theme.
     *
     * @param gravity See {@link android.view.Gravity}
     *
     * @attr ref android.R.styleable#Spinner_gravity
     */
    public void setGravity(int gravity) {
        if (mGravity != gravity) {
            if ((gravity & Gravity.HORIZONTAL_GRAVITY_MASK) == 0) {
                gravity |= Gravity.START;
            }
            mGravity = gravity;
            requestLayout();
        }
    }

    Describes how the selected item view is positioned. The default is determined by the
current theme.
Returns: A Gravity value/**
     * Describes how the selected item view is positioned. The default is determined by the
     * current theme.
     *
     * @return A {@link android.view.Gravity Gravity} value
     */
    public int getGravity() {
        return mGravity;
    }

    Sets the SpinnerAdapter used to provide the data which backs this Spinner.  If this Spinner has a popup theme set in XML via the popupTheme attribute, the adapter should inflate drop-down views using the same theme. The easiest way to achieve this is by using getPopupContext() to obtain a layout inflater for use in SpinnerAdapter.getDropDownView(int, View, ViewGroup). 
 Spinner overrides Adapter.getViewTypeCount() on the Adapter associated with this view. Calling getItemViewType(int) on the object returned from AbsSpinner.getAdapter() will always return 0. Calling getViewTypeCount() will always return 1. On API VERSION_CODES.LOLLIPOP and above, attempting to set an adapter with more than one view type will throw an IllegalArgumentException. 
Params: adapter – the adapter to set
Throws: IllegalArgumentException – if the adapter has more than one view
        type
See Also: AbsSpinner.setAdapter(SpinnerAdapter)/**
     * Sets the {@link SpinnerAdapter} used to provide the data which backs
     * this Spinner.
     * <p>
     * If this Spinner has a popup theme set in XML via the
     * {@link android.R.styleable#Spinner_popupTheme popupTheme} attribute, the
     * adapter should inflate drop-down views using the same theme. The easiest
     * way to achieve this is by using {@link #getPopupContext()} to obtain a
     * layout inflater for use in
     * {@link SpinnerAdapter#getDropDownView(int, View, ViewGroup)}.
     * <p>
     * Spinner overrides {@link Adapter#getViewTypeCount()} on the
     * Adapter associated with this view. Calling
     * {@link Adapter#getItemViewType(int) getItemViewType(int)} on the object
     * returned from {@link #getAdapter()} will always return 0. Calling
     * {@link Adapter#getViewTypeCount() getViewTypeCount()} will always return
     * 1. On API {@link Build.VERSION_CODES#LOLLIPOP} and above, attempting to set an
     * adapter with more than one view type will throw an
     * {@link IllegalArgumentException}.
     *
     * @param adapter the adapter to set
     *
     * @see AbsSpinner#setAdapter(SpinnerAdapter)
     * @throws IllegalArgumentException if the adapter has more than one view
     *         type
     */
    @Override
    public void setAdapter(SpinnerAdapter adapter) {
        // The super constructor may call setAdapter before we're prepared.
        // Postpone doing anything until we've finished construction.
        if (mPopup == null) {
            mTempAdapter = adapter;
            return;
        }

        super.setAdapter(adapter);

        mRecycler.clear();

        final int targetSdkVersion = mContext.getApplicationInfo().targetSdkVersion;
        if (targetSdkVersion >= Build.VERSION_CODES.LOLLIPOP
                && adapter != null && adapter.getViewTypeCount() != 1) {
            throw new IllegalArgumentException("Spinner adapter view type count must be 1");
        }

        final Context popupContext = mPopupContext == null ? mContext : mPopupContext;
        mPopup.setAdapter(new DropDownAdapter(adapter, popupContext.getTheme()));
    }

    @Override
    public int getBaseline() {
        View child = null;

        if (getChildCount() > 0) {
            child = getChildAt(0);
        } else if (mAdapter != null && mAdapter.getCount() > 0) {
            child = makeView(0, false);
            mRecycler.put(0, child);
        }

        if (child != null) {
            final int childBaseline = child.getBaseline();
            return childBaseline >= 0 ? child.getTop() + childBaseline : -1;
        } else {
            return -1;
        }
    }

    @Override
    protected void onDetachedFromWindow() {
        super.onDetachedFromWindow();

        if (mPopup != null && mPopup.isShowing()) {
            mPopup.dismiss();
        }
    }

    A spinner does not support item click events. Calling this method
will raise an exception.
Instead use AdapterView.setOnItemSelectedListener. 
Params: l – this listener will be ignored/**
     * <p>A spinner does not support item click events. Calling this method
     * will raise an exception.</p>
     * <p>Instead use {@link AdapterView#setOnItemSelectedListener}.
     *
     * @param l this listener will be ignored
     */
    @Override
    public void setOnItemClickListener(OnItemClickListener l) {
        throw new RuntimeException("setOnItemClickListener cannot be used with a spinner.");
    }

    @hide internal use only/**
     * @hide internal use only
     */
    public void setOnItemClickListenerInt(OnItemClickListener l) {
        super.setOnItemClickListener(l);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        if (mForwardingListener != null && mForwardingListener.onTouch(this, event)) {
            return true;
        }

        return super.onTouchEvent(event);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        if (mPopup != null && MeasureSpec.getMode(widthMeasureSpec) == MeasureSpec.AT_MOST) {
            final int measuredWidth = getMeasuredWidth();
            setMeasuredDimension(Math.min(Math.max(measuredWidth,
                    measureContentWidth(getAdapter(), getBackground())),
                    MeasureSpec.getSize(widthMeasureSpec)),
                    getMeasuredHeight());
        }
    }

    See Also: 
Creates and positions all views/**
     * @see android.view.View#onLayout(boolean,int,int,int,int)
     *
     * Creates and positions all views
     *
     */
    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        super.onLayout(changed, l, t, r, b);
        mInLayout = true;
        layout(0, false);
        mInLayout = false;
    }

    Creates and positions all views for this Spinner.
Params: delta – Change in the selected position. +1 means selection is moving to the right,
so views are scrolling to the left. -1 means selection is moving to the left./**
     * Creates and positions all views for this Spinner.
     *
     * @param delta Change in the selected position. +1 means selection is moving to the right,
     * so views are scrolling to the left. -1 means selection is moving to the left.
     */
    @Override
    void layout(int delta, boolean animate) {
        int childrenLeft = mSpinnerPadding.left;
        int childrenWidth = mRight - mLeft - mSpinnerPadding.left - mSpinnerPadding.right;

        if (mDataChanged) {
            handleDataChanged();
        }

        // Handle the empty set by removing all views
        if (mItemCount == 0) {
            resetList();
            return;
        }

        if (mNextSelectedPosition >= 0) {
            setSelectedPositionInt(mNextSelectedPosition);
        }

        recycleAllViews();

        // Clear out old views
        removeAllViewsInLayout();

        // Make selected view and position it
        mFirstPosition = mSelectedPosition;

        if (mAdapter != null) {
            View sel = makeView(mSelectedPosition, true);
            int width = sel.getMeasuredWidth();
            int selectedOffset = childrenLeft;
            final int layoutDirection = getLayoutDirection();
            final int absoluteGravity = Gravity.getAbsoluteGravity(mGravity, layoutDirection);
            switch (absoluteGravity & Gravity.HORIZONTAL_GRAVITY_MASK) {
                case Gravity.CENTER_HORIZONTAL:
                    selectedOffset = childrenLeft + (childrenWidth / 2) - (width / 2);
                    break;
                case Gravity.RIGHT:
                    selectedOffset = childrenLeft + childrenWidth - width;
                    break;
            }
            sel.offsetLeftAndRight(selectedOffset);
        }

        // Flush any cached views that did not get reused above
        mRecycler.clear();

        invalidate();

        checkSelectionChanged();

        mDataChanged = false;
        mNeedSync = false;
        setNextSelectedPositionInt(mSelectedPosition);
    }

    Obtain a view, either by pulling an existing view from the recycler or
by getting a new one from the adapter. If we are animating, make sure
there is enough information in the view's layout parameters to animate
from the old to new positions.
Params: position – Position in the spinner for the view to obtain
addChild – true to add the child to the spinner, false to obtain and configure only.
Returns: A view for the given position/**
     * Obtain a view, either by pulling an existing view from the recycler or
     * by getting a new one from the adapter. If we are animating, make sure
     * there is enough information in the view's layout parameters to animate
     * from the old to new positions.
     *
     * @param position Position in the spinner for the view to obtain
     * @param addChild true to add the child to the spinner, false to obtain and configure only.
     * @return A view for the given position
     */
    private View makeView(int position, boolean addChild) {
        View child;

        if (!mDataChanged) {
            child = mRecycler.get(position);
            if (child != null) {
                // Position the view
                setUpChild(child, addChild);

                return child;
            }
        }

        // Nothing found in the recycler -- ask the adapter for a view
        child = mAdapter.getView(position, null, this);

        // Position the view
        setUpChild(child, addChild);

        return child;
    }

    Helper for makeAndAddView to set the position of a view
and fill out its layout paramters.
Params: child – The view to position
addChild – true if the child should be added to the Spinner during setup/**
     * Helper for makeAndAddView to set the position of a view
     * and fill out its layout paramters.
     *
     * @param child The view to position
     * @param addChild true if the child should be added to the Spinner during setup
     */
    private void setUpChild(View child, boolean addChild) {

        // Respect layout params that are already in the view. Otherwise
        // make some up...
        ViewGroup.LayoutParams lp = child.getLayoutParams();
        if (lp == null) {
            lp = generateDefaultLayoutParams();
        }

        addViewInLayout(child, 0, lp);

        child.setSelected(hasFocus());
        if (mDisableChildrenWhenDisabled) {
            child.setEnabled(isEnabled());
        }

        // Get measure specs
        int childHeightSpec = ViewGroup.getChildMeasureSpec(mHeightMeasureSpec,
                mSpinnerPadding.top + mSpinnerPadding.bottom, lp.height);
        int childWidthSpec = ViewGroup.getChildMeasureSpec(mWidthMeasureSpec,
                mSpinnerPadding.left + mSpinnerPadding.right, lp.width);

        // Measure child
        child.measure(childWidthSpec, childHeightSpec);

        int childLeft;
        int childRight;

        // Position vertically based on gravity setting
        int childTop = mSpinnerPadding.top
                + ((getMeasuredHeight() - mSpinnerPadding.bottom -
                        mSpinnerPadding.top - child.getMeasuredHeight()) / 2);
        int childBottom = childTop + child.getMeasuredHeight();

        int width = child.getMeasuredWidth();
        childLeft = 0;
        childRight = childLeft + width;

        child.layout(childLeft, childTop, childRight, childBottom);

        if (!addChild) {
            removeViewInLayout(child);
        }
    }

    @Override
    public boolean performClick() {
        boolean handled = super.performClick();

        if (!handled) {
            handled = true;

            if (!mPopup.isShowing()) {
                mPopup.show(getTextDirection(), getTextAlignment());
            }
        }

        return handled;
    }

    @Override
    public void onClick(DialogInterface dialog, int which) {
        setSelection(which);
        dialog.dismiss();
    }

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

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

        if (mAdapter != null) {
            info.setCanOpenPopup(true);
        }
    }

    Sets the prompt to display when the dialog is shown.
Params: prompt – the prompt to set/**
     * Sets the prompt to display when the dialog is shown.
     * @param prompt the prompt to set
     */
    public void setPrompt(CharSequence prompt) {
        mPopup.setPromptText(prompt);
    }

    Sets the prompt to display when the dialog is shown.
Params: promptId – the resource ID of the prompt to display when the dialog is shown/**
     * Sets the prompt to display when the dialog is shown.
     * @param promptId the resource ID of the prompt to display when the dialog is shown
     */
    public void setPromptId(int promptId) {
        setPrompt(getContext().getText(promptId));
    }

    Returns: The prompt to display when the dialog is shown/**
     * @return The prompt to display when the dialog is shown
     */
    public CharSequence getPrompt() {
        return mPopup.getHintText();
    }

    int measureContentWidth(SpinnerAdapter adapter, Drawable background) {
        if (adapter == null) {
            return 0;
        }

        int width = 0;
        View itemView = null;
        int itemType = 0;
        final int widthMeasureSpec =
            MeasureSpec.makeSafeMeasureSpec(getMeasuredWidth(), MeasureSpec.UNSPECIFIED);
        final int heightMeasureSpec =
            MeasureSpec.makeSafeMeasureSpec(getMeasuredHeight(), MeasureSpec.UNSPECIFIED);

        // Make sure the number of items we'll measure is capped. If it's a huge data set
        // with wildly varying sizes, oh well.
        int start = Math.max(0, getSelectedItemPosition());
        final int end = Math.min(adapter.getCount(), start + MAX_ITEMS_MEASURED);
        final int count = end - start;
        start = Math.max(0, start - (MAX_ITEMS_MEASURED - count));
        for (int i = start; i < end; i++) {
            final int positionType = adapter.getItemViewType(i);
            if (positionType != itemType) {
                itemType = positionType;
                itemView = null;
            }
            itemView = adapter.getView(i, itemView, this);
            if (itemView.getLayoutParams() == null) {
                itemView.setLayoutParams(new ViewGroup.LayoutParams(
                        ViewGroup.LayoutParams.WRAP_CONTENT,
                        ViewGroup.LayoutParams.WRAP_CONTENT));
            }
            itemView.measure(widthMeasureSpec, heightMeasureSpec);
            width = Math.max(width, itemView.getMeasuredWidth());
        }

        // Add background padding to measured width
        if (background != null) {
            background.getPadding(mTempRect);
            width += mTempRect.left + mTempRect.right;
        }

        return width;
    }

    @Override
    public Parcelable onSaveInstanceState() {
        final SavedState ss = new SavedState(super.onSaveInstanceState());
        ss.showDropdown = mPopup != null && mPopup.isShowing();
        return ss;
    }

    @Override
    public void onRestoreInstanceState(Parcelable state) {
        SavedState ss = (SavedState) state;

        super.onRestoreInstanceState(ss.getSuperState());

        if (ss.showDropdown) {
            ViewTreeObserver vto = getViewTreeObserver();
            if (vto != null) {
                final OnGlobalLayoutListener listener = new OnGlobalLayoutListener() {
                    @Override
                    public void onGlobalLayout() {
                        if (!mPopup.isShowing()) {
                            mPopup.show(getTextDirection(), getTextAlignment());
                        }
                        final ViewTreeObserver vto = getViewTreeObserver();
                        if (vto != null) {
                            vto.removeOnGlobalLayoutListener(this);
                        }
                    }
                };
                vto.addOnGlobalLayoutListener(listener);
            }
        }
    }

    @Override
    public PointerIcon onResolvePointerIcon(MotionEvent event, int pointerIndex) {
        if (getPointerIcon() == null && isClickable() && isEnabled()) {
            return PointerIcon.getSystemIcon(getContext(), PointerIcon.TYPE_HAND);
        }
        return super.onResolvePointerIcon(event, pointerIndex);
    }

    static class SavedState extends AbsSpinner.SavedState {
        boolean showDropdown;

        SavedState(Parcelable superState) {
            super(superState);
        }

        private SavedState(Parcel in) {
            super(in);
            showDropdown = in.readByte() != 0;
        }

        @Override
        public void writeToParcel(Parcel out, int flags) {
            super.writeToParcel(out, flags);
            out.writeByte((byte) (showDropdown ? 1 : 0));
        }

        public static final Parcelable.Creator<SavedState> CREATOR =
                new Parcelable.Creator<SavedState>() {
            public SavedState createFromParcel(Parcel in) {
                return new SavedState(in);
            }

            public SavedState[] newArray(int size) {
                return new SavedState[size];
            }
        };
    }

    Wrapper class for an Adapter. Transforms the embedded Adapter instance
into a ListAdapter.
/**
     * <p>Wrapper class for an Adapter. Transforms the embedded Adapter instance
     * into a ListAdapter.</p>
     */
    private static class DropDownAdapter implements ListAdapter, SpinnerAdapter {
        private SpinnerAdapter mAdapter;
        private ListAdapter mListAdapter;

        Creates a new ListAdapter wrapper for the specified adapter.
Params: adapter – the SpinnerAdapter to transform into a ListAdapter
dropDownTheme – the theme against which to inflate drop-down
                     views, may be {@null} to use default theme/**
         * Creates a new ListAdapter wrapper for the specified adapter.
         *
         * @param adapter the SpinnerAdapter to transform into a ListAdapter
         * @param dropDownTheme the theme against which to inflate drop-down
         *                      views, may be {@null} to use default theme
         */
        public DropDownAdapter(@Nullable SpinnerAdapter adapter,
                @Nullable Resources.Theme dropDownTheme) {
            mAdapter = adapter;

            if (adapter instanceof ListAdapter) {
                mListAdapter = (ListAdapter) adapter;
            }

            if (dropDownTheme != null && adapter instanceof ThemedSpinnerAdapter) {
                final ThemedSpinnerAdapter themedAdapter = (ThemedSpinnerAdapter) adapter;
                if (themedAdapter.getDropDownViewTheme() == null) {
                    themedAdapter.setDropDownViewTheme(dropDownTheme);
                }
            }
        }

        public int getCount() {
            return mAdapter == null ? 0 : mAdapter.getCount();
        }

        public Object getItem(int position) {
            return mAdapter == null ? null : mAdapter.getItem(position);
        }

        public long getItemId(int position) {
            return mAdapter == null ? -1 : mAdapter.getItemId(position);
        }

        public View getView(int position, View convertView, ViewGroup parent) {
            return getDropDownView(position, convertView, parent);
        }

        public View getDropDownView(int position, View convertView, ViewGroup parent) {
            return (mAdapter == null) ? null : mAdapter.getDropDownView(position, convertView, parent);
        }

        public boolean hasStableIds() {
            return mAdapter != null && mAdapter.hasStableIds();
        }

        public void registerDataSetObserver(DataSetObserver observer) {
            if (mAdapter != null) {
                mAdapter.registerDataSetObserver(observer);
            }
        }

        public void unregisterDataSetObserver(DataSetObserver observer) {
            if (mAdapter != null) {
                mAdapter.unregisterDataSetObserver(observer);
            }
        }

        If the wrapped SpinnerAdapter is also a ListAdapter, delegate this call.
Otherwise, return true.
/**
         * If the wrapped SpinnerAdapter is also a ListAdapter, delegate this call.
         * Otherwise, return true.
         */
        public boolean areAllItemsEnabled() {
            final ListAdapter adapter = mListAdapter;
            if (adapter != null) {
                return adapter.areAllItemsEnabled();
            } else {
                return true;
            }
        }

        If the wrapped SpinnerAdapter is also a ListAdapter, delegate this call.
Otherwise, return true.
/**
         * If the wrapped SpinnerAdapter is also a ListAdapter, delegate this call.
         * Otherwise, return true.
         */
        public boolean isEnabled(int position) {
            final ListAdapter adapter = mListAdapter;
            if (adapter != null) {
                return adapter.isEnabled(position);
            } else {
                return true;
            }
        }

        public int getItemViewType(int position) {
            return 0;
        }

        public int getViewTypeCount() {
            return 1;
        }

        public boolean isEmpty() {
            return getCount() == 0;
        }
    }

    Implements some sort of popup selection interface for selecting a spinner option.
Allows for different spinner modes.
/**
     * Implements some sort of popup selection interface for selecting a spinner option.
     * Allows for different spinner modes.
     */
    private interface SpinnerPopup {
        public void setAdapter(ListAdapter adapter);

        Show the popup
/**
         * Show the popup
         */
        public void show(int textDirection, int textAlignment);

        Dismiss the popup
/**
         * Dismiss the popup
         */
        public void dismiss();

        Returns: true if the popup is showing, false otherwise./**
         * @return true if the popup is showing, false otherwise.
         */
        public boolean isShowing();

        Set hint text to be displayed to the user. This should provide
a description of the choice being made.
Params: hintText – Hint text to set./**
         * Set hint text to be displayed to the user. This should provide
         * a description of the choice being made.
         * @param hintText Hint text to set.
         */
        public void setPromptText(CharSequence hintText);
        public CharSequence getHintText();

        public void setBackgroundDrawable(Drawable bg);
        public void setVerticalOffset(int px);
        public void setHorizontalOffset(int px);
        public Drawable getBackground();
        public int getVerticalOffset();
        public int getHorizontalOffset();
    }

    private class DialogPopup implements SpinnerPopup, DialogInterface.OnClickListener {
        private AlertDialog mPopup;
        private ListAdapter mListAdapter;
        private CharSequence mPrompt;

        public void dismiss() {
            if (mPopup != null) {
                mPopup.dismiss();
                mPopup = null;
            }
        }

        public boolean isShowing() {
            return mPopup != null ? mPopup.isShowing() : false;
        }

        public void setAdapter(ListAdapter adapter) {
            mListAdapter = adapter;
        }

        public void setPromptText(CharSequence hintText) {
            mPrompt = hintText;
        }

        public CharSequence getHintText() {
            return mPrompt;
        }

        public void show(int textDirection, int textAlignment) {
            if (mListAdapter == null) {
                return;
            }
            AlertDialog.Builder builder = new AlertDialog.Builder(getPopupContext());
            if (mPrompt != null) {
                builder.setTitle(mPrompt);
            }
            mPopup = builder.setSingleChoiceItems(mListAdapter,
                    getSelectedItemPosition(), this).create();
            final ListView listView = mPopup.getListView();
            listView.setTextDirection(textDirection);
            listView.setTextAlignment(textAlignment);
            mPopup.show();
        }

        public void onClick(DialogInterface dialog, int which) {
            setSelection(which);
            if (mOnItemClickListener != null) {
                performItemClick(null, which, mListAdapter.getItemId(which));
            }
            dismiss();
        }

        @Override
        public void setBackgroundDrawable(Drawable bg) {
            Log.e(TAG, "Cannot set popup background for MODE_DIALOG, ignoring");
        }

        @Override
        public void setVerticalOffset(int px) {
            Log.e(TAG, "Cannot set vertical offset for MODE_DIALOG, ignoring");
        }

        @Override
        public void setHorizontalOffset(int px) {
            Log.e(TAG, "Cannot set horizontal offset for MODE_DIALOG, ignoring");
        }

        @Override
        public Drawable getBackground() {
            return null;
        }

        @Override
        public int getVerticalOffset() {
            return 0;
        }

        @Override
        public int getHorizontalOffset() {
            return 0;
        }
    }

    private class DropdownPopup extends ListPopupWindow implements SpinnerPopup {
        private CharSequence mHintText;
        private ListAdapter mAdapter;

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

            setAnchorView(Spinner.this);
            setModal(true);
            setPromptPosition(POSITION_PROMPT_ABOVE);
            setOnItemClickListener(new OnItemClickListener() {
                public void onItemClick(AdapterView parent, View v, int position, long id) {
                    Spinner.this.setSelection(position);
                    if (mOnItemClickListener != null) {
                        Spinner.this.performItemClick(v, position, mAdapter.getItemId(position));
                    }
                    dismiss();
                }
            });
        }

        @Override
        public void setAdapter(ListAdapter adapter) {
            super.setAdapter(adapter);
            mAdapter = adapter;
        }

        public CharSequence getHintText() {
            return mHintText;
        }

        public void setPromptText(CharSequence hintText) {
            // Hint text is ignored for dropdowns, but maintain it here.
            mHintText = hintText;
        }

        void computeContentWidth() {
            final Drawable background = getBackground();
            int hOffset = 0;
            if (background != null) {
                background.getPadding(mTempRect);
                hOffset = isLayoutRtl() ? mTempRect.right : -mTempRect.left;
            } else {
                mTempRect.left = mTempRect.right = 0;
            }

            final int spinnerPaddingLeft = Spinner.this.getPaddingLeft();
            final int spinnerPaddingRight = Spinner.this.getPaddingRight();
            final int spinnerWidth = Spinner.this.getWidth();

            if (mDropDownWidth == WRAP_CONTENT) {
                int contentWidth =  measureContentWidth(
                        (SpinnerAdapter) mAdapter, getBackground());
                final int contentWidthLimit = mContext.getResources()
                        .getDisplayMetrics().widthPixels - mTempRect.left - mTempRect.right;
                if (contentWidth > contentWidthLimit) {
                    contentWidth = contentWidthLimit;
                }
                setContentWidth(Math.max(
                       contentWidth, spinnerWidth - spinnerPaddingLeft - spinnerPaddingRight));
            } else if (mDropDownWidth == MATCH_PARENT) {
                setContentWidth(spinnerWidth - spinnerPaddingLeft - spinnerPaddingRight);
            } else {
                setContentWidth(mDropDownWidth);
            }

            if (isLayoutRtl()) {
                hOffset += spinnerWidth - spinnerPaddingRight - getWidth();
            } else {
                hOffset += spinnerPaddingLeft;
            }
            setHorizontalOffset(hOffset);
        }

        public void show(int textDirection, int textAlignment) {
            final boolean wasShowing = isShowing();

            computeContentWidth();

            setInputMethodMode(ListPopupWindow.INPUT_METHOD_NOT_NEEDED);
            super.show();
            final ListView listView = getListView();
            listView.setChoiceMode(ListView.CHOICE_MODE_SINGLE);
            listView.setTextDirection(textDirection);
            listView.setTextAlignment(textAlignment);
            setSelection(Spinner.this.getSelectedItemPosition());

            if (wasShowing) {
                // Skip setting up the layout/dismiss listener below. If we were previously
                // showing it will still stick around.
                return;
            }

            // Make sure we hide if our anchor goes away.
            // TODO: This might be appropriate to push all the way down to PopupWindow,
            // but it may have other side effects to investigate first. (Text editing handles, etc.)
            final ViewTreeObserver vto = getViewTreeObserver();
            if (vto != null) {
                final OnGlobalLayoutListener layoutListener = new OnGlobalLayoutListener() {
                    @Override
                    public void onGlobalLayout() {
                        if (!Spinner.this.isVisibleToUser()) {
                            dismiss();
                        } else {
                            computeContentWidth();

                            // Use super.show here to update; we don't want to move the selected
                            // position or adjust other things that would be reset otherwise.
                            DropdownPopup.super.show();
                        }
                    }
                };
                vto.addOnGlobalLayoutListener(layoutListener);
                setOnDismissListener(new OnDismissListener() {
                    @Override public void onDismiss() {
                        final ViewTreeObserver vto = getViewTreeObserver();
                        if (vto != null) {
                            vto.removeOnGlobalLayoutListener(layoutListener);
                        }
                    }
                });
            }
        }
    }

}
@attr	ref android.R.styleable#Spinner_dropDownSelector
@attr	ref android.R.styleable#Spinner_dropDownWidth
@attr	ref android.R.styleable#Spinner_gravity
@attr	ref android.R.styleable#Spinner_popupBackground
@attr	ref android.R.styleable#Spinner_prompt
@attr	ref android.R.styleable#Spinner_spinnerMode
@attr	ref android.R.styleable#ListPopupWindow_dropDownVerticalOffset
@attr	ref android.R.styleable#ListPopupWindow_dropDownHorizontalOffset
Params:	context – The Context the view is running in, through which it can access the current theme, resources, etc. mode – Constant describing how the user will select choices from the spinner.
See Also:	MODE_DIALOG MODE_DROPDOWN
Params:	background – Background drawable
@attr	ref android.R.styleable#Spinner_popupBackground
Params:	resId – Resource ID of a background drawable
@attr	ref android.R.styleable#Spinner_popupBackground
Returns:	background Background drawable
@attr	ref android.R.styleable#Spinner_popupBackground
Params:	pixels – Vertical offset in pixels
@attr	ref android.R.styleable#ListPopupWindow_dropDownVerticalOffset
Returns:	Vertical offset in pixels
@attr	ref android.R.styleable#ListPopupWindow_dropDownVerticalOffset
Params:	pixels – Horizontal offset in pixels
@attr	ref android.R.styleable#ListPopupWindow_dropDownHorizontalOffset
Returns:	Horizontal offset in pixels
@attr	ref android.R.styleable#ListPopupWindow_dropDownHorizontalOffset
Params:	pixels – Width in pixels, WRAP_CONTENT, or MATCH_PARENT
@attr	ref android.R.styleable#Spinner_dropDownWidth
Returns:	Width in pixels, WRAP_CONTENT, or MATCH_PARENT
@attr	ref android.R.styleable#Spinner_dropDownWidth
Params:	gravity – See `Gravity`
@attr	ref android.R.styleable#Spinner_gravity
Params:	adapter – the adapter to set
Throws:	IllegalArgumentException – if the adapter has more than one view type
See Also:	AbsSpinner.setAdapter(SpinnerAdapter)
Params:	position – Position in the spinner for the view to obtain addChild – true to add the child to the spinner, false to obtain and configure only.
Returns:	A view for the given position
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android/ android-9.0.0_r35/ android/widget/Spinner.java
