Retrieve the Source code from your favorite Android Application

As a Developer some time we will eager to know what logic the popular production application (eg: whatsApp) uses internally. Here is a way to view our popular app's source code, i am just sharing the procedure

Even in a unrooted device this works,
Install this App from ur Gplay
https://play.google.com/store/apps/details?id=com.ext.ui&hl=en

Now choose the desires app which you need the apk, the apk will be exported to the sd-card,
from sd-card unzip the apk and use https://code.google.com/p/dex2jar/ to view the class