Android Radio Buttons 

In Android, you can use “android.widget.RadioButton” class to render radio button, and those radio buttons are usually grouped by android.widget.RadioGroup. If RadioButtons are in group, when one RadioButton within a group is selected, all others are automatically deselected.

In this tutorial, we show you how to use XML to create two radio buttons, and grouped in a radio group. When button is clicked, display which radio button is selected.

P.S This project is developed in Eclipse 3.7, and tested with Android 2.3.3.

1. Custom String

Open “res/values/strings.xml” file, add some custom string for radio button.

File : res/values/strings.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string name="hello">Hello World, MyAndroidAppActivity!</string>
    <string name="app_name">MyAndroidApp</string>
    <string name="radio_male">Male</string>
    <string name="radio_female">Female</string>
    <string name="btn_display">Display</string>
</resources>

2. RadioButton

Open “res/layout/main.xml” file, add “RadioGroup“, “RadioButton” and a button, inside the LinearLayout.

File : res/layout/main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >
 
    <RadioGroup
        android:id="@+id/radioSex"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" >
 
        <RadioButton
            android:id="@+id/radioMale"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/radio_male" 
            android:checked="true" />
 
        <RadioButton
            android:id="@+id/radioFemale"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/radio_female" />
 
    </RadioGroup>
 
    <Button
        android:id="@+id/btnDisplay"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/btn_display" />
 
</LinearLayout>

Radio button selected by default.
To make a radio button is selected by default, put android:checked="true" within the RadioButton element. In this case, radio option “Male” is selected by default.

3. Code Code

Inside activity “onCreate()” method, attach a click listener on button.

File : MyAndroidAppActivity.java

package com.mkyong.android;
 
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.Toast;
 
public class MyAndroidAppActivity extends Activity {
 
  private RadioGroup radioSexGroup;
  private RadioButton radioSexButton;
  private Button btnDisplay;
 
  @Override
  public void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.main);
 
 addListenerOnButton();
 
  }
 
  public void addListenerOnButton() {
 
 radioSexGroup = (RadioGroup) findViewById(R.id.radioSex);
 btnDisplay = (Button) findViewById(R.id.btnDisplay);
 
 btnDisplay.setOnClickListener(new OnClickListener() {
 
  @Override
  public void onClick(View v) {
 
          // get selected radio button from radioGroup
   int selectedId = radioSexGroup.getCheckedRadioButtonId();
 
   // find the radiobutton by returned id
          radioSexButton = (RadioButton) findViewById(selectedId);
 
   Toast.makeText(MyAndroidAppActivity.this,
    radioSexButton.getText(), Toast.LENGTH_SHORT).show();
 
  }
 
 });
 
  }
}