android RaidoGroup的使用与监听

<?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:orientation="horizontal" >

    <RadioGroup
        android:id="@+id/radioGroup1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal" >

        <RadioButton
            android:id="@+id/radio0"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:checked="true"
            android:text="男" />

        <RadioButton
            android:id="@+id/radio1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="女" />
    </RadioGroup>

</LinearLayout>

package com.example.hello;

import android.support.v7.app.ActionBarActivity;
import android.widget.RadioGroup;
import android.widget.Toast;
import android.widget.RadioGroup.OnCheckedChangeListener;
import android.os.Bundle;


public class MainActivity extends ActionBarActivity implements OnCheckedChangeListener{
    
    private RadioGroup rg;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        rg = (RadioGroup) findViewById(R.id.radioGroup1);
        rg.setOnCheckedChangeListener(this);
        
    }
    @Override
    public void onCheckedChanged(RadioGroup group, int checkedId) {
        switch(checkedId){
            case R.id.radio0:
                Toast.makeText(MainActivity.this, "男", 1).show();
                break;
            case R.id.radio1:
                Toast.makeText(MainActivity.this, "女", 1).show();
                break;
        }
        
    }
}