Jme physics 2, detect if player is on the ground [SOLVED]

Hey, I just want to know if there is an easy way to detect if the player is on the ground (to determine if the player is allowed to jump). In my case I want to know if a PhysicsSphere intersetcts with a PhysicsBox.  I don't really understand the way it's described in the "Walking and Jumping Character with jME-physics" tutorial. Due to this I don't get it to work with my code.


SOLUTION if somebody has the same problem: I got the example from the physics tutorial to work. I made the mistake to create a new InputHandler object, but the object input is already defined anywhere in simplephysicsgame.