Android Application Development Cookbook: 93 Recipes for Building Winning Apps

Recipe 2.3 Using Radio Buttons

Android Versions

Level 1 and above

Permissions

None

Source Code to Download from Wrox.com

RadioButtons.zip

Radio buttons enable users to select one item from a list of available options. This recipe shows how to use radio buttons in your Android application.

Solution

Assume you have the following code snippet in your activity_main.xml file:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <RadioGroup
        android:id="@+id/rdbGp1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical" >

        <RadioButton
            android:id="@+id/rdb1"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:drawableLeft="@drawable/ic_launcher"
            android:text="Option 1" />

        <RadioButton
            android:id="@+id/rdb2"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:drawableLeft="@drawable/ic_launcher"
            android:text="Option 2" 
            android:checked="true"/>
    </RadioGroup>

</LinearLayout>

The RadioButton element represents a two-state button that can be either checked or unchecked. Once a radio button is checked, it cannot be unchecked by tapping on it. Instead, radio buttons are contained within a RadioGroup element, which contains a set of radio buttons. Checking one radio button in a radio group unchecks the rest of the radio buttons in the same group. ...