Maximizing / Minimizing bar on android

I'm trying to make my MainActivity divided on 3 parts. One listview on top, another listview on bottom and one little bar in the middle with 2 buttons, one will make the bar go directly to the top "hidding" the first list (and maximizing the other one) and vice versa if the user clicks on the second button. My question is: The propper approach to this is to make a custom view with and animate it manually or there is a easier way to do it?