阅读《Android 从入门到精通》（10）——单项选择

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单项选择（RadioGroup）

RadioGroup 是 LinearLayout 的子类，继承关系如下：

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

RadioGroup 类方法

RadioGroup 示例

完整工程：http://download.csdn.net/detail/sweetloveft/9402088
下述程序中，主要学习 RadioGroup 的用法，需要注意单选按钮的处理逻辑是通过监听 RadioGroup 完成的，具体处理哪个单选按钮则是通过 getId() 完成的。

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;@Overrideprotected void onCreate(Bundle savedInstanceState) {// TODO Auto-generated method stubsuper.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 {@Overridepublic void onCheckedChanged(RadioGroup group, int checkedId) {// TODO Auto-generated method stubfor (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">操作系统</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>

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