Android : How to update the selector(StateListDrawable) programmatically

I want to update the selector for a button programmatically. I can do this with the xml file which is given below ``` <?xml version="1.0" encoding="UTF-8"?> <selector xmlns:android="http://schemas.android.com/apk/res/android"> <item android:state_enabled="false" android:drawable="@drawable/btn_off" /> <item android:state_pressed="true" android:state_enabled="true" android:drawable="@drawable/btn_off" /> <item android:state_focused="true" android:state_enabled="true" android:drawable="@drawable/btn_on" /> <item android:state_enabled="true" android:drawable="@drawable/btn_on" /> </selector> ``` I want to do the same thing programmatically. I have tried something like given below ``` private StateListDrawable setImageButtonState(int index) { StateListDrawable states = new StateListDrawable(); states.addState(new int[] {android.R.attr.stateNotNeeded},R.drawable.btn_off); states.addState(new int[] {android.R.attr.state_pressed, android.R.attr.state_enabled},R.drawable.btn_off); states.addState(new int[] {android.R.attr.state_focused, android.R.attr.state_enabled},R.drawable.btn_on); states.addState(new int[] {android.R.attr.state_enabled},R.drawable.btn_on); return states; } ``` but it didnt work. And how to set `android:state_enabled="false"` or `android:state_enabled="true"` programatically.