How can I change between displaying 2D or 3D objects

Hello,

I want to display 2D or 3D objects.
My main problem: I display a 2D-Object with displayImplJ2D and want to
display a new 3D-Object with displayImplJ3D.
Can I change between displayImplJ2D and displayImplJ3D
or can I tell the 3D-Display to look like a 2D-Display
or is there a posibility to reinitialize the displayImpl?

Greetings Erik