在平常使用軟體的時候，我們經常會碰見一些選擇題，例如選擇性別的時候，在男和女之間選，前面說過這個情況要用RadioGroup元件，那麼點選了之後我們該怎麼獲取到選擇的那個值呢，這就是今天要說的OnCheckedChangeListener方法。這個方法定義如下：

public static interface RadioGroup.OnCheckedChangeListener{
	    public void onCheckedChanged(RadioGroup group, int checkedId){
	    	
	    }
	}

點選前：

點選後：

下面給出程式原始檔：

main.xml：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/LinearLayout1"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
    <TextView 
        android:id="@+id/title"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:textSize="20sp"
        android:text="請選擇您的性別...."/>
	<RadioGroup 
	    android:id="@+id/sex"
	    android:layout_width="fill_parent"
	    android:layout_height="wrap_content"
	    android:orientation="vertical"
	    android:checkedButton="@+id/male">
	    <RadioButton 
	        android:id="@+id/male"
	        android:text="男"/>
	    <RadioButton 
	        android:id="@+id/female"
	        android:text="女"/>
	</RadioGroup>
	<TextView 
	    android:id="@+id/showSex"
	    android:layout_width="fill_parent"
	    android:layout_height="wrap_content"
	    android:text="您的性別是："/>
</LinearLayout>
 

package com.example.oncheckedchangedlistenerdemo;

import android.app.Activity;
import android.os.Bundle;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.TextView;

public class MainActivity extends Activity {
	private TextView showSex = null;
	private RadioGroup sex = null;
	private RadioButton male = null;
	private RadioButton female = null;
	private String head = "";
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		initView();
	}
	
	private void initView(){
		//初始化元件
		showSex = (TextView)super.findViewById(R.id.showSex);
		sex = (RadioGroup)super.findViewById(R.id.sex);
		male = (RadioButton)super.findViewById(R.id.male);
		female = (RadioButton)super.findViewById(R.id.female);
		//獲取顯示字首（即您的性別是：），以便顯示美觀
		head = showSex.getText().toString();
		//未呼叫監聽時顯示預設選擇內容
		if(male.getId() == sex.getCheckedRadioButtonId()){
			showSex.setText(head+male.getText().toString());
		}else if(female.getId() == sex.getCheckedRadioButtonId()){
			showSex.setText(head+female.getText().toString());
		}
		//為RadioGroup設定監聽事件
		sex.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
			
			@Override
			public void onCheckedChanged(RadioGroup group, int checkedId) {
				// TODO Auto-generated method stub
				String sexTmp = "";
				if(checkedId == male.getId()){
					sexTmp = male.getText().toString();
				}else if(checkedId == female.getId()){
					sexTmp = female.getText().toString();
				}
				showSex.setText(head+sexTmp);
			}
		});
	}
}