單項選擇（RadioGroup）

RadioGroup 是 LinearLayout 的子類，繼承關系例如以下：

android.view.ViewGroup
android.widget.LinearLayout
android.widget.RadioGroup

RadioGroup 類方法

RadioGroup 演示樣例

完整project：http://download.csdn.net/detail/sweetloveft/9402088
下述程序中，主要學習 RadioGroup 的使用方法，須要註意單選button的處理邏輯是通過監聽 RadioGroup 完畢的，詳細處理哪個單選button則是通過 getId() 完畢的。

1.MainActivity.java

package com.sweetlover.activity;

import com.sweetlover.radiogroupdemo.R;

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

public class MainActivity extends Activity {

	private static final int BTN_NUM = 6;
	
	private TextView textView = null;
	private RadioGroup radioGroup = null;
	private RadioButton[] radioButton = null;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		// TODO Auto-generated method stub
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		radioButton = new RadioButton[BTN_NUM];
		textView = (TextView)findViewById(R.id.textView1);
		radioGroup = (RadioGroup)findViewById(R.id.radioGroup);
		radioButton[0] = (RadioButton)findViewById(R.id.radioButton1);
		radioButton[1] = (RadioButton)findViewById(R.id.radioButton2);
		radioButton[2] = (RadioButton)findViewById(R.id.radioButton3);
		radioButton[3] = (RadioButton)findViewById(R.id.radioButton4);
		radioButton[4] = (RadioButton)findViewById(R.id.radioButton5);
		radioButton[5] = (RadioButton)findViewById(R.id.radioButton6);
		
		radioGroup.setOnCheckedChangeListener(new RadioGroupCheckedListener());
	}

	class RadioGroupCheckedListener implements OnCheckedChangeListener {

		@Override
		public void onCheckedChanged(RadioGroup group, int checkedId) {
			// TODO Auto-generated method stub
			for (int i = 0; i < BTN_NUM; i++) {
				if (checkedId == radioButton[i].getId() && radioButton[i].isChecked()) {
					CharSequence text = radioButton[i].getText();
					textView.setText(text);
					Toast.makeText(MainActivity.this, text, Toast.LENGTH_SHORT).show();
					break;
				}
			}
		}
	}
}

2.activity_main.xml

<?
xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="30dp"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:text="@string/system"
        android:textAppearance="?
 
android:attr/textAppearanceMedium" />
    
    <RadioGroup
        android:id="@+id/radioGroup"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:padding="30dp" >

        <RadioButton
            android:id="@+id/radioButton1"
            android:layout_width="160dp"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:text="@string/os1" />
        
        <RadioButton
            android:id="@+id/radioButton2"
            android:layout_width="160dp"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:text="@string/os2" />
        
        <RadioButton
            android:id="@+id/radioButton3"
            android:layout_width="160dp"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:text="@string/os3" />
        
        <RadioButton
            android:id="@+id/radioButton4"
            android:layout_width="160dp"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:text="@string/os4" />
        
        <RadioButton
            android:id="@+id/radioButton5"
            android:layout_width="160dp"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:text="@string/os5" />
        
        <RadioButton
            android:id="@+id/radioButton6"
            android:layout_width="160dp"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:text="@string/os6" />
        
    </RadioGroup>

</LinearLayout>

3.string.xml

<resources>

    <string name="app_name">RadioGroupDemo</string>
    <string name="system">操作系統</string>
    <string name="os1">Android</string>
    <string name="os2">Sysbian</string>
    <string name="os3">WinCE</string>
    <string name="os4">PalmOS</string>
    <string name="os5">Linux</string>
    <string name="os6">iPhoneOS</string>

</resources>

4.AndroidManifest.xml

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.sweetlover.radiogroupdemo"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="19" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity android:name="com.sweetlover.activity.MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
    </application>

</manifest>

閱讀《Android 從入門到精通》（10）——單項選擇