Instead of declaring
private MapFragment _mapFragment;
do
private SupportMapFragment _mapFragment;
Also make sure that
- you have imported android.support.v4.app.Fragment
- you have android.support.v4.jar in your libs folder and in the project build path
Copy android.support.v4.jar into a lib/ folder inside of your project.
Now select the jar file in that folder, right click -> Build Path -> Add To Build Path.