第20章、OnCheckedChangeListener事件（从零开始学Android）

单选按钮RadioGroup、复选框CheckBox都有OnCheckedChangeListener事件，我们一起了解一下。

一、布局

　　1、打开“res/layout/activity_main.xml”文件。

<RelativeLayout     xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    tools:context=".MainActivity" >    <RadioGroup        android:id="@+id/gender"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignParentLeft="true"        android:layout_alignParentTop="true" >        <RadioButton            android:id="@+id/male"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:checked="true"            android:text="男" />        <RadioButton            android:id="@+id/female"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="女" />    </RadioGroup>    <CheckBox        android:id="@+id/football"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignParentLeft="true"        android:layout_below="@+id/gender"        android:text="足球" />    <CheckBox        android:id="@+id/basketball"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignParentLeft="true"        android:layout_below="@+id/football"        android:text="蓝球" /></RelativeLayout>

　　2、界面如下：

二、OnCheckedChangeListener事件　

　　打开“src/com.genwoxue.oncheckedchanged/MainActivity.java”文件。

　　然后输入以下代码：　　

package com.genwoxue.oncheckedchanged;import android.os.Bundle;import android.app.Activity;import android.widget.RadioGroup;import android.widget.RadioButton;import android.widget.RadioGroup.OnCheckedChangeListener;              //引入OnCheckedChangeListener事件相关包import android.widget.CheckBox;import android.widget.CompoundButton;import android.widget.Toast;public class MainActivity extends Activity {private RadioGroup GenderGroup=null;private RadioButton rbMale=null;private RadioButton rbFemale=null;private CheckBox cbFootBall=null;private CheckBox cbBasketBall=null;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);GenderGroup=(RadioGroup)super.findViewById(R.id.gender);rbMale=(RadioButton)super.findViewById(R.id.male);rbFemale=(RadioButton)super.findViewById(R.id.female);cbFootBall=(CheckBox)super.findViewById(R.id.football);cbBasketBall=(CheckBox)super.findViewById(R.id.basketball);//在GenderGroup注册OnCheckedChangeListener事件                  GenderGroup.setOnCheckedChangeListener(new GenderOnCheckedChangeListener());                  //在cbFootBall注册OnCheckedChangeListener事件cbFootBall.setOnCheckedChangeListener(new BootBallOnCheckedChangeListener());                  //在cbBasketBall注册OnCheckedChangeListener事件cbBasketBall.setOnCheckedChangeListener(new BasketBallOnCheckedChangeListener());}private class GenderOnCheckedChangeListener implements OnCheckedChangeListener{@Overridepublic void onCheckedChanged(RadioGroup group,int checkedId){String sGender="";if(rbFemale.getId()==checkedId){sGender=rbFemale.getText().toString();}if(rbMale.getId()==checkedId){sGender=rbMale.getText().toString();}Toast.makeText(getApplicationContext(), "您选择的性别是："+sGender, Toast.LENGTH_LONG).show();}}private class BootBallOnCheckedChangeListener implements CompoundButton.OnCheckedChangeListener{@Overridepublic void onCheckedChanged(CompoundButton button, boolean isChecked){String sFav="";if(isChecked){sFav=cbFootBall.getText().toString();sFav=sFav+"选中！";}elsesFav=sFav+"未迁中";Toast.makeText(getApplicationContext(), "您选择的爱好是："+sFav, Toast.LENGTH_LONG).show();}}private class BasketBallOnCheckedChangeListener implements CompoundButton.OnCheckedChangeListener{@Overridepublic void onCheckedChanged(CompoundButton button,boolean isChecked){String sFav="";if(cbBasketBall.isChecked()){sFav=cbBasketBall.getText().toString();sFav=sFav+"选中！";}elsesFav=sFav+"未迁中";Toast.makeText(getApplicationContext(), "您选择的爱好是："+sFav, Toast.LENGTH_LONG).show();}}}

　　尽管单选按钮和复选框都有OnCheckedChange事件，但注意二者区别。

　　效果如下：

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