as was suggested in your previous post... one idea is to create an interface for the chess piece:
Then you can implement this class for each type of chess piece. You'll have to come up with a scheme to determine if a given move is allowed.
For example... for a knight they can move (ummm I forget) 1 forward and 3 to the side?? so given the current position, is (x,y) the position that is 1 space forward and 3 to the side? Also is (x,y) even on the board? Is another piece occupying that space?
Maybe your Board class will have methods like
Does that make sense? Try thinking along those lines and see what you come up with.