Radio Button

From google material design documentation.

Radio buttons allow the user to select one option from a set. Use radio buttons for exclusive selection if you think that the user needs to see all available options side-by-side.

Otherwise, consider a dropdown, which uses less space than displaying all options.

How to add?

I. In your build.gradle add latest appcompat library.

dependencies {  
    compile 'com.android.support:appcompat-v7:X.X.X' // where X.X.X version
}

II. Make your activity extend android.support.v7.app.AppCompatActivity.

public class MainActivity extends AppCompatActivity {  
    ...
}

III. Declare your RadioButton inside any layout.xml file

<RadioButton  
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:checked="true"
    android:text="Radio Button"/>

How to style?

I. Declare custom style in your styles.xml file.

<style name="MyRadioButton" parent="Theme.AppCompat.Light">  
    <item name="colorControlNormal">@color/indigo</item>
    <item name="colorControlActivated">@color/pink</item>
</style>  

II. Apply this style to your RadioButton via android:theme attribute.

<RadioButton  
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:checked="true"
    android:text="Radio Button"
    android:theme="@style/MyRadioButton"/>