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。。
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。。
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* 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;
}
* <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);
} /**
* <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, int checkedId);
} private class CheckedStateTracker implements CompoundButton.OnCheckedChangeListener {
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}
*/
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 = child.hashCode();
child.setId(id);
}
((RadioButton) child).setOnCheckedChangeWidgetListener(
mChildOnCheckedChangeListener);
} if (mOnHierarchyChangeListener != null) {
mOnHierarchyChangeListener.onChildViewAdded(parent, child);
}
} /**
* {@inheritDoc}
*/
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);
}
}
}
}
onCheckedChanged 实现了listener
这跟java调用匿名内部类是一样的原理