Change height of a custom actionbar using java

I am stuck in an issue. I'm a junior android developer. I want to change the height of my custom action bar on a click event. But I'm not able to find the way that how to change actionbar's height. I saw other related posts, but didnt find exactly what I need. I want to toggle a hidden layout part of action bar, upon click event. The height of action should fit to the content size each time.