Round button in Android

Question

I want to create a circular button having a plus and minus sign on to this and exactly used in Android Contacts application like shown in the image as below:

Answer 1

You may see implementation of this button in android source code

It's just ImageButton with circular png as background. Here is definition of their styles:

<style name="MinusButton">
    <item name="android:background">@drawable/btn_circle</item>
    <item name="android:src">@drawable/ic_btn_round_minus</item>
    <item name="android:contentDescription">@string/description_minus_button</item>
</style>

<style name="PlusButton">
    <item name="android:background">@drawable/btn_circle</item>
    <item name="android:src">@drawable/ic_btn_round_plus</item>
    <item name="android:contentDescription">@string/description_plus_button</item>
</style>