As you can see in image, I want shadow behind a Button. I have created Button with rounded corners. But problem is I can't generate a shadow behind that Button. How can I achieve this?
Since none of the answers here really address the question, I wanted to point out https://github.com/Devlight/ShadowLayout (not my project). This is a simple Android layout you can wrap around anything to give it a shadow. The library is a single class and only ~250 lines. The README says deprecated, but it works great.
Wrapping all your views isn't ideal, but until Android provides a standard mechanism to introduce a shadow, or you want to draw all of your button states as bitmaps that include the shadow pixels, this is the best option I could fine.