android button custum state_pressed

http://mrbool.com/how-to-customize-different-buttons-in-android/27747

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android" >
    <item android:state_pressed="true" 
        android:drawable="@drawable/one">
</item>
  
    <item android:drawable="@drawable/two"> //these is the normal state of button when it is not pressed. And the background is provided when it is not pressed.
</item>

</selector>