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，继承关系例如以下：

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

RadioGroup 类方法

RadioGroup 演示样例

完整project：http://download.csdn.net/detail/sweetloveft/9402088
下述程序中，主要学习 RadioGroup 的使用方法，须要注意单选button的处理逻辑是通过监听 RadioGroup 完毕的，详细处理哪个单选button则是通过 getId() 完毕的。

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>