android - How to change rectangle colour when user touches it -

i place rectangle on android screen placing drawable background relativelayout. following how achieve it.

<relativelayout xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"     android:layout_height="match_parent"     android:background="@android:color/white">      <relativelayout         android:layout_width="200dp"         android:layout_height="150dp"         android:background="@drawable/welcome_rectangle"         android:id="@+id/rectangular_orange"         android:layout_centerinparent="true"></relativelayout>  </relativelayout> 

the following xml drawable welcome_rectangle.

<?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/green_welcome_rectangle" />     <item android:drawable="@drawable/orange_welcome_rectangle" /> </selector> 

i want colour of rectangle change when user touches it. hasn't been achieved selector written. how can change selector code can want?