Try this......
First create an xml file named button_pressed.xml These are it's contents.
<?xml version="1.0" encoding="utf-8"?>
<selector
xmlns:android="http://schemas.android.com/apk/res/android">
<item android:state_focused="true"
android:state_pressed="false"
android:drawable="@drawable/icon_1" />
<item android:state_focused="true"
android:state_pressed="true"
android:drawable="@drawable/icon_1_press" />
<item android:state_focused="false"
android:state_pressed="true"
android:drawable="@drawable/icon_1_press" />
<item android:drawable="@drawable/icon_1" />
</selector>
Noe try this on your button.
int imgID = getResources().getIdentifier("button_pressed", "drawable", getApplication().getPackageName());
button.setImageResource(imgID);
button_pressed.xml should be in the drawable folder. icon_1_press and icon_1 are two images for button press and normal focus.