Tab bar & navigation bar on Android.

Currently, I want to port an application from iPhone platform to Android flatform. The first problem I faced is tab bar & navigation bar of iPhone. Fortunately, I've found the solution for coding already. But now, I face another problem: how to design it?
My solution is use the existing tab bar of Android. When user navigate the screen, I hold on the old activity. By this way, when user return back to any old screen, I can display it with the old status easily.

Please help me. Thanks.