android开发中setOnCheckedChangeListener监听的问题（高手进）
setOnCheckedChangeListener 他的监听原理是什么啊?
传入一个RadioGroup.OnCheckedChangeListener 内部接口类，（实现这个接口类中的onCheckedChanged方法。）
setOnCheckedChangeListener 的底层源码是什么啊？
android API中的介绍
他是怎么调用传进来的这个接口类中的onCheckedChanged方法的??
这个onCheckedChanged 方法需要向里面传入两个参数 RadioGroup group 和 int checkedId..他是怎么传入的？？
说白了 我就是不是很明白 这个回调函数的原理，或者说 这个回调函数的原理是怎么在这个类中体现的。。
或者说是 我理解错了
public void setOnHierarchyChangeListener (ViewGroup.OnHierarchyChangeListener listener)
Since: API Level 1 Register a callback to be invoked when a child is added to or removed from this view.
Parameters
listener the callback to invoke on hierarchy change
他这句话的意思是说setOnHierarchyChangeListener 是回调函数 还是说
ViewGroup.OnHierarchyChangeListener listener中的onCheckedChanged 方法是回调函数呢？
希望高收帮忙解答一下，纠结一下午了。。
[解决办法]
这个是android系统radiogroup的源码，你可以参考研究研究。
/*
* 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 com.android.internal.R;
import android.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
/**
* <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 {
// 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;
/**
* {@inheritDoc}
*/
public RadioGroup(Context context) {
super(context);
setOrientation(VERTICAL);
init();
}
/**
* {@inheritDoc}
*/
public RadioGroup(Context context, AttributeSet attrs) {
super(context, attrs);
// 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;
}
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(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(int id) {
mCheckedId = id;
if (mOnCheckedChangeListener != null) {
mOnCheckedChangeListener.onCheckedChanged(this, mCheckedId);
}
}
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()
*/
public int getCheckedRadioButtonId() {
return mCheckedId;
}
[解决办法]
先调用setOnHierarchyChangeListener
onCheckedChanged 实现了listener
这跟java调用匿名内部类是一样的原理
