Android 单选框RadioGroup

package com.radiodemo;

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

public class MainActivity extends Activity {

  /*************************************
   * 单选框RadioButton的使用
   * 
   * 1.定义见布局文件 2.事件的添加方法
   * 
   ***********************************/

  private TextView textView;
  private RadioGroup radioGroup;
  private RadioButton radioButton1, radioButton2;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    // 关联布局中的控件
    textView = (TextView) findViewById(R.id.textView);// 用来显示选择
    radioGroup = (RadioGroup) findViewById(R.id.radioGroup);
    radioButton1 = (RadioButton) findViewById(R.id.radioButton1);
    radioButton2 = (RadioButton) findViewById(R.id.radioButton2);

    radioGroup.setOnCheckedChangeListener(mChangeListener);
  }

  // 响应事件的函数。
  private RadioGroup.OnCheckedChangeListener mChangeListener = new RadioGroup.OnCheckedChangeListener() {

    @Override
    public void onCheckedChanged(RadioGroup group, int checkedId) {
      // TODO Auto-generated method stub

      if (radioButton1.getId() == checkedId) {
        textView.setText(radioButton1.getText());
      } else {
        textView.setText(radioButton2.getText());
      }

    }
  };

  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
  }
}

    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="请问你是谁" />

    <RadioGroup
        android:id="@+id/radioGroup"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical" >

        <RadioButton
            android:id="@+id/radioButton1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="男的" >
        
        <RadioButton
            android:id="@+id/radioButton2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="女的" >