Java tutorial
/* * 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.UnsupportedAppUsage; 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; /** * <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 @UnsupportedAppUsage private CompoundButton.OnCheckedChangeListener mChildOnCheckedChangeListener; // when true, mOnCheckedChangeListener discards events private boolean mProtectFromCheckedChange = false; @UnsupportedAppUsage 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} */ public RadioGroup(Context context) { super(context); setOrientation(VERTICAL); init(); } /** * {@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} */ @Override public void setOnHierarchyChangeListener(OnHierarchyChangeListener listener) { // the user listener is delegated to our pass-through listener mPassThroughListener.mOnHierarchyChangeListener = listener; } /** * {@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); } /** * <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); } } /** * <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; } /** * <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); } /** * <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} */ @Override public LayoutParams generateLayoutParams(AttributeSet attrs) { return new RadioGroup.LayoutParams(getContext(), attrs); } /** * {@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(); } /** * <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} */ public LayoutParams(Context c, AttributeSet attrs) { super(c, attrs); } /** * {@inheritDoc} */ public LayoutParams(int w, int h) { super(w, h); } /** * {@inheritDoc} */ public LayoutParams(int w, int h, float initWeight) { super(w, h, initWeight); } /** * {@inheritDoc} */ public LayoutParams(ViewGroup.LayoutParams p) { super(p); } /** * {@inheritDoc} */ public LayoutParams(MarginLayoutParams source) { super(source); } /** * <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; } } } /** * <p>Interface definition for a callback to be invoked when the checked * radio button changed in this group.</p> */ public interface OnCheckedChangeListener { /** * <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); } } /** * <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} */ @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} */ @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; } }