Android学习实践：10.单选按钮RadioButton

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在项目中新建一个Android Activity,名为RadioButtonActivity，layout文件名为activity_radiobutton，title设为"单选"

activity_radiobutton.xml内容如下：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:id="@+id/LinearLayout1"    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"    tools:context="maxwoods.demo1.RadioButtonActivity" ><RadioGroup    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:id="@+id/radioGroup01">    <RadioButton        android:id="@+id/RadioButton01"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="大" />    <RadioButton        android:id="@+id/radioButton1"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="小" /></RadioGroup><RadioGroup    android:layout_width="match_parent"    android:layout_height="wrap_content"     android:id="@+id/radioGroup02">    <RadioButton        android:id="@+id/RadioButton03"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="高" />    <RadioButton        android:id="@+id/radioButton4"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="低" /></RadioGroup>    <TextView        android:id="@+id/textView1"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:text="TextView" /></LinearLayout>

上面使用了RadioGroup为每对互斥的选项进行了分组，同一个RadioGroup中的RadioButton只有一个能为选中状态。

RadioButtonActivity.java代码如下：

package maxwoods.demo1;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.Menu;import android.view.MenuItem;import android.widget.RadioButton;import android.widget.RadioGroup;import android.widget.TextView;import android.widget.RadioGroup.OnCheckedChangeListener;public class RadioButtonActivity extends AppCompatActivity implements OnCheckedChangeListener{@Overrideprotected void onCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.activity_radiobutton);    RadioGroup rg01=(RadioGroup)findViewById(R.id.radioGroup01);    rg01.setOnCheckedChangeListener(this);    RadioGroup rg02=(RadioGroup)findViewById(R.id.radioGroup02);    rg02.setOnCheckedChangeListener(this);}@Overridepublic boolean onCreateOptionsMenu(Menu menu){// Inflate the menu; this adds items to the action bar if it is present.getMenuInflater().inflate(R.menu.check_radio, menu);return true;}@Overridepublic boolean onOptionsItemSelected(MenuItem item){// Handle action bar item clicks here. The action bar will// automatically handle clicks on the Home/Up button, so long// as you specify a parent activity in AndroidManifest.xml.int id = item.getItemId();if (id == R.id.action_settings){return true;}return super.onOptionsItemSelected(item);}public void onCheckedChanged(RadioGroup group, int checkedId){StringBuilder sb=new StringBuilder();TextView tv=(TextView)findViewById(R.id.textView1);if(group.getId()==R.id.radioGroup01){sb.append("选择大小组\n");}else if(group.getId()==R.id.radioGroup02){sb.append("选择高低组\n");}RadioButton rb=(RadioButton)findViewById(checkedId);sb.append(rb.getText());tv.setText(sb.toString());}}

需要注意的是，事件监听代码应用于RadioGroup,在onCheckedChanged对单选按钮的选择作出响应，参数group为触发事件的RadioGroup，checkedId为所选的RadioButton的Id。最终运行效果如下图：

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