https://source.android.com/ 
/*
 * 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.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewStructure;
import android.view.autofill.AutofillManager;
import android.view.autofill.AutofillValue;

import com.android.internal.R;



This class is used to create a multiple-exclusion scope for a set of radio
buttons. Checking one radio button that belongs to a radio group unchecks
any previously checked radio button within the same group.


Intially, all of the radio buttons are unchecked. While it is not possible
to uncheck a particular radio button, the radio group can be cleared to
remove the checked state.


The selection is identified by the unique id of the radio button as defined
in the XML layout file.


XML Attributes


See RadioGroup Attributes, LinearLayout Attributes, ViewGroup Attributes, View Attributes


Also see LinearLayout.LayoutParams for layout attributes.


See Also:
/**
 * <p>This class is used to create a multiple-exclusion scope for a set of radio
 * buttons. Checking one radio button that belongs to a radio group unchecks
 * any previously checked radio button within the same group.</p>
 *
 * <p>Intially, all of the radio buttons are unchecked. While it is not possible
 * to uncheck a particular radio button, the radio group can be cleared to
 * remove the checked state.</p>
 *
 * <p>The selection is identified by the unique id of the radio button as defined
 * in the XML layout file.</p>
 *
 * <p><strong>XML Attributes</strong></p>
 * <p>See {@link android.R.styleable#RadioGroup RadioGroup Attributes},
 * {@link android.R.styleable#LinearLayout LinearLayout Attributes},
 * {@link android.R.styleable#ViewGroup ViewGroup Attributes},
 * {@link android.R.styleable#View View Attributes}</p>
 * <p>Also see
 * {@link android.widget.LinearLayout.LayoutParams LinearLayout.LayoutParams}
 * for layout attributes.</p>
 *
 * @see RadioButton
 *
 */
public class RadioGroup extends LinearLayout {
    private static final String LOG_TAG = RadioGroup.class.getSimpleName();

    // holds the checked id; the selection is empty by default
    private int mCheckedId = -1;
    // tracks children radio buttons checked state
    private CompoundButton.OnCheckedChangeListener mChildOnCheckedChangeListener;
    // when true, mOnCheckedChangeListener discards events
    private boolean mProtectFromCheckedChange = false;
    private OnCheckedChangeListener mOnCheckedChangeListener;
    private PassThroughHierarchyChangeListener mPassThroughListener;

    // Indicates whether the child was set from resources or dynamically, so it can be used
    // to sanitize autofill requests.
    private int mInitialCheckedId = View.NO_ID;

    
{@inheritDoc}

/**
     * {@inheritDoc}
     */
    public RadioGroup(Context context) {
        super(context);
        setOrientation(VERTICAL);
        init();
    }

    
{@inheritDoc}

/**
     * {@inheritDoc}
     */
    public RadioGroup(Context context, AttributeSet attrs) {
        super(context, attrs);

        // RadioGroup is important by default, unless app developer overrode attribute.
        if (getImportantForAutofill() == IMPORTANT_FOR_AUTOFILL_AUTO) {
            setImportantForAutofill(IMPORTANT_FOR_AUTOFILL_YES);
        }

        // retrieve selected radio button as requested by the user in the
        // XML layout file
        TypedArray attributes = context.obtainStyledAttributes(
                attrs, com.android.internal.R.styleable.RadioGroup, com.android.internal.R.attr.radioButtonStyle, 0);

        int value = attributes.getResourceId(R.styleable.RadioGroup_checkedButton, View.NO_ID);
        if (value != View.NO_ID) {
            mCheckedId = value;
            mInitialCheckedId = value;
        }
        final int index = attributes.getInt(com.android.internal.R.styleable.RadioGroup_orientation, VERTICAL);
        setOrientation(index);

        attributes.recycle();
        init();
    }

    private void init() {
        mChildOnCheckedChangeListener = new CheckedStateTracker();
        mPassThroughListener = new PassThroughHierarchyChangeListener();
        super.setOnHierarchyChangeListener(mPassThroughListener);
    }

    
{@inheritDoc}

/**
     * {@inheritDoc}
     */
    @Override
    public void setOnHierarchyChangeListener(OnHierarchyChangeListener listener) {
        // the user listener is delegated to our pass-through listener
        mPassThroughListener.mOnHierarchyChangeListener = listener;
    }

    
{@inheritDoc}

/**
     * {@inheritDoc}
     */
    @Override
    protected void onFinishInflate() {
        super.onFinishInflate();

        // checks the appropriate radio button as requested in the XML file
        if (mCheckedId != -1) {
            mProtectFromCheckedChange = true;
            setCheckedStateForView(mCheckedId, true);
            mProtectFromCheckedChange = false;
            setCheckedId(mCheckedId);
        }
    }

    @Override
    public void addView(View child, int index, ViewGroup.LayoutParams params) {
        if (child instanceof RadioButton) {
            final RadioButton button = (RadioButton) child;
            if (button.isChecked()) {
                mProtectFromCheckedChange = true;
                if (mCheckedId != -1) {
                    setCheckedStateForView(mCheckedId, false);
                }
                mProtectFromCheckedChange = false;
                setCheckedId(button.getId());
            }
        }

        super.addView(child, index, params);
    }

    
Sets the selection to the radio button whose identifier is passed in parameter. Using -1 as the selection identifier clears the selection; such an operation is equivalent to invoking clearCheck().


Params:
  • id – the unique id of the radio button to select in this group
See Also:
/**
     * <p>Sets the selection to the radio button whose identifier is passed in
     * parameter. Using -1 as the selection identifier clears the selection;
     * such an operation is equivalent to invoking {@link #clearCheck()}.</p>
     *
     * @param id the unique id of the radio button to select in this group
     *
     * @see #getCheckedRadioButtonId()
     * @see #clearCheck()
     */
    public void check(@IdRes int id) {
        // don't even bother
        if (id != -1 && (id == mCheckedId)) {
            return;
        }

        if (mCheckedId != -1) {
            setCheckedStateForView(mCheckedId, false);
        }

        if (id != -1) {
            setCheckedStateForView(id, true);
        }

        setCheckedId(id);
    }

    private void setCheckedId(@IdRes int id) {
        boolean changed = id != mCheckedId;
        mCheckedId = id;

        if (mOnCheckedChangeListener != null) {
            mOnCheckedChangeListener.onCheckedChanged(this, mCheckedId);
        }
        if (changed) {
            final AutofillManager afm = mContext.getSystemService(AutofillManager.class);
            if (afm != null) {
                afm.notifyValueChanged(this);
            }
        }
    }

    private void setCheckedStateForView(int viewId, boolean checked) {
        View checkedView = findViewById(viewId);
        if (checkedView != null && checkedView instanceof RadioButton) {
            ((RadioButton) checkedView).setChecked(checked);
        }
    }

    
Returns the identifier of the selected radio button in this group.
Upon empty selection, the returned value is -1.


See Also:
Returns:the unique id of the selected radio button in this group
@attrref android.R.styleable#RadioGroup_checkedButton
/**
     * <p>Returns the identifier of the selected radio button in this group.
     * Upon empty selection, the returned value is -1.</p>
     *
     * @return the unique id of the selected radio button in this group
     *
     * @see #check(int)
     * @see #clearCheck()
     *
     * @attr ref android.R.styleable#RadioGroup_checkedButton
     */
    @IdRes
    public int getCheckedRadioButtonId() {
        return mCheckedId;
    }

    
Clears the selection. When the selection is cleared, no radio button in this group is selected and getCheckedRadioButtonId() returns null.


See Also:
/**
     * <p>Clears the selection. When the selection is cleared, no radio button
     * in this group is selected and {@link #getCheckedRadioButtonId()} returns
     * null.</p>
     *
     * @see #check(int)
     * @see #getCheckedRadioButtonId()
     */
    public void clearCheck() {
        check(-1);
    }

    
Register a callback to be invoked when the checked radio button
changes in this group.


Params:
  • listener – the callback to call on checked state change
/**
     * <p>Register a callback to be invoked when the checked radio button
     * changes in this group.</p>
     *
     * @param listener the callback to call on checked state change
     */
    public void setOnCheckedChangeListener(OnCheckedChangeListener listener) {
        mOnCheckedChangeListener = listener;
    }

    
{@inheritDoc}

/**
     * {@inheritDoc}
     */
    @Override
    public LayoutParams generateLayoutParams(AttributeSet attrs) {
        return new RadioGroup.LayoutParams(getContext(), attrs);
    }

    
{@inheritDoc}

/**
     * {@inheritDoc}
     */
    @Override
    protected boolean checkLayoutParams(ViewGroup.LayoutParams p) {
        return p instanceof RadioGroup.LayoutParams;
    }

    @Override
    protected LinearLayout.LayoutParams generateDefaultLayoutParams() {
        return new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
    }

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

    
This set of layout parameters defaults the width and the height of the children to LayoutParams.WRAP_CONTENT when they are not specified in the XML file. Otherwise, this class ussed the value read from the XML file.


See LinearLayout Attributes for a list of all child view attributes that this class supports.


/**
     * <p>This set of layout parameters defaults the width and the height of
     * the children to {@link #WRAP_CONTENT} when they are not specified in the
     * XML file. Otherwise, this class ussed the value read from the XML file.</p>
     *
     * <p>See
     * {@link android.R.styleable#LinearLayout_Layout LinearLayout Attributes}
     * for a list of all child view attributes that this class supports.</p>
     *
     */
    public static class LayoutParams extends LinearLayout.LayoutParams {
        
{@inheritDoc}

/**
         * {@inheritDoc}
         */
        public LayoutParams(Context c, AttributeSet attrs) {
            super(c, attrs);
        }

        
{@inheritDoc}

/**
         * {@inheritDoc}
         */
        public LayoutParams(int w, int h) {
            super(w, h);
        }

        
{@inheritDoc}

/**
         * {@inheritDoc}
         */
        public LayoutParams(int w, int h, float initWeight) {
            super(w, h, initWeight);
        }

        
{@inheritDoc}

/**
         * {@inheritDoc}
         */
        public LayoutParams(ViewGroup.LayoutParams p) {
            super(p);
        }

        
{@inheritDoc}

/**
         * {@inheritDoc}
         */
        public LayoutParams(MarginLayoutParams source) {
            super(source);
        }

        
Fixes the child's width to LayoutParams.WRAP_CONTENT and the child's height to LayoutParams.WRAP_CONTENT when not specified in the XML file.


Params:
  • a – the styled attributes set
  • widthAttr – the width attribute to fetch
  • heightAttr – the height attribute to fetch
/**
         * <p>Fixes the child's width to
         * {@link android.view.ViewGroup.LayoutParams#WRAP_CONTENT} and the child's
         * height to  {@link android.view.ViewGroup.LayoutParams#WRAP_CONTENT}
         * when not specified in the XML file.</p>
         *
         * @param a the styled attributes set
         * @param widthAttr the width attribute to fetch
         * @param heightAttr the height attribute to fetch
         */
        @Override
        protected void setBaseAttributes(TypedArray a,
                int widthAttr, int heightAttr) {

            if (a.hasValue(widthAttr)) {
                width = a.getLayoutDimension(widthAttr, "layout_width");
            } else {
                width = WRAP_CONTENT;
            }

            if (a.hasValue(heightAttr)) {
                height = a.getLayoutDimension(heightAttr, "layout_height");
            } else {
                height = WRAP_CONTENT;
            }
        }
    }

    
Interface definition for a callback to be invoked when the checked
radio button changed in this group.


/**
     * <p>Interface definition for a callback to be invoked when the checked
     * radio button changed in this group.</p>
     */
    public interface OnCheckedChangeListener {
        
Called when the checked radio button has changed. When the
selection is cleared, checkedId is -1.


Params:
  • group – the group in which the checked radio button has changed
  • checkedId – the unique identifier of the newly checked radio button
/**
         * <p>Called when the checked radio button has changed. When the
         * selection is cleared, checkedId is -1.</p>
         *
         * @param group the group in which the checked radio button has changed
         * @param checkedId the unique identifier of the newly checked radio button
         */
        public void onCheckedChanged(RadioGroup group, @IdRes int checkedId);
    }

    private class CheckedStateTracker implements CompoundButton.OnCheckedChangeListener {
        @Override
        public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
            // prevents from infinite recursion
            if (mProtectFromCheckedChange) {
                return;
            }

            mProtectFromCheckedChange = true;
            if (mCheckedId != -1) {
                setCheckedStateForView(mCheckedId, false);
            }
            mProtectFromCheckedChange = false;

            int id = buttonView.getId();
            setCheckedId(id);
        }
    }

    
A pass-through listener acts upon the events and dispatches them
to another listener. This allows the table layout to set its own internal
hierarchy change listener without preventing the user to setup his.


/**
     * <p>A pass-through listener acts upon the events and dispatches them
     * to another listener. This allows the table layout to set its own internal
     * hierarchy change listener without preventing the user to setup his.</p>
     */
    private class PassThroughHierarchyChangeListener implements
            ViewGroup.OnHierarchyChangeListener {
        private ViewGroup.OnHierarchyChangeListener mOnHierarchyChangeListener;

        
{@inheritDoc}

/**
         * {@inheritDoc}
         */
        @Override
        public void onChildViewAdded(View parent, View child) {
            if (parent == RadioGroup.this && child instanceof RadioButton) {
                int id = child.getId();
                // generates an id if it's missing
                if (id == View.NO_ID) {
                    id = View.generateViewId();
                    child.setId(id);
                }
                ((RadioButton) child).setOnCheckedChangeWidgetListener(
                        mChildOnCheckedChangeListener);
            }

            if (mOnHierarchyChangeListener != null) {
                mOnHierarchyChangeListener.onChildViewAdded(parent, child);
            }
        }

        
{@inheritDoc}

/**
         * {@inheritDoc}
         */
        @Override
        public void onChildViewRemoved(View parent, View child) {
            if (parent == RadioGroup.this && child instanceof RadioButton) {
                ((RadioButton) child).setOnCheckedChangeWidgetListener(null);
            }

            if (mOnHierarchyChangeListener != null) {
                mOnHierarchyChangeListener.onChildViewRemoved(parent, child);
            }
        }
    }

    @Override
    public void onProvideAutofillStructure(ViewStructure structure, int flags) {
        super.onProvideAutofillStructure(structure, flags);
        structure.setDataIsSensitive(mCheckedId != mInitialCheckedId);
    }

    @Override
    public void autofill(AutofillValue value) {
        if (!isEnabled()) return;

        if (!value.isList()) {
            Log.w(LOG_TAG, value + " could not be autofilled into " + this);
            return;
        }

        final int index = value.getListValue();
        final View child = getChildAt(index);
        if (child == null) {
            Log.w(VIEW_LOG_TAG, "RadioGroup.autoFill(): no child with index " + index);
            return;
        }

        check(child.getId());
    }

    @Override
    public @AutofillType int getAutofillType() {
        return isEnabled() ? AUTOFILL_TYPE_LIST : AUTOFILL_TYPE_NONE;
    }

    @Override
    public AutofillValue getAutofillValue() {
        if (!isEnabled()) return null;

        final int count = getChildCount();
        for (int i = 0; i < count; i++) {
            final View child = getChildAt(i);
            if (child.getId() == mCheckedId) {
                return AutofillValue.forList(i);
            }
        }
        return null;
    }
}