本文将通过radiogroup和radiobutton实现组内信息的单选, 

其中radiogroup就是将radiobutton进行分组,同一管理和控制

同时实现默认选中情况,获取默认值.效果图

具体实例如下：

1.activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin" >

    <TextView
        android:id="@+id/diplay_seleted_item_tv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" 
        android:text="@string/please_selected"/>

    <RadioGroup
        android:id="@+id/sex_rg"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="#00FF00"
        android:orientation="vertical" >

        <RadioButton
            android:id="@+id/man_rb"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/man" />

        <RadioButton
            android:id="@+id/woman_rb"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/woman" />
    </RadioGroup>

</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <string name="app_name">RadioGroupDemo</string>
    <string name="please_selected">请选择你的性别：</string>
    <string name="action_settings">Settings</string>
    <string name="man">男</string>
    <string name="woman">女</string>

</resources>

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        defaultStr = this.getResources().getString(R.string.please_selected);
        seletedTv = (TextView) this.findViewById(R.id.diplay_seleted_item_tv);
        sexRg = (RadioGroup) this.findViewById(R.id.sex_rg);
        manRb = (RadioButton) this.findViewById(R.id.man_rb);
        womanRb = (RadioButton) this.findViewById(R.id.woman_rb);
        
        manRb.setChecked(true);
        seletedTv.setText(defaultStr + manRb.getText().toString());
        
        sexRg.setOnCheckedChangeListener(new OnCheckedChangeListener(){

			@Override
			public void onCheckedChanged(RadioGroup rg, int checkedId) {
				// TODO Auto-generated method stub
				if(checkedId == manRb.getId()){
					seletedTv.setText(defaultStr + manRb.getText().toString());
				}else if(checkedId == womanRb.getId()){
					seletedTv.setText(defaultStr + womanRb.getText().toString());
				}else{
					seletedTv.setText(defaultStr);
				}
			}
        });
    }