Trouble assigning sub class to super class array

Question

Hi,
I would greatly appreciate some help with the following:
I want to assign a sub class to a super class array but the following code does not work
where the board is comprised of the super class
     private static void makeMove( int X, int Y, int moveX, int moveY )
          ChessPiece tempChessPiece = ( ChessPiece ) board[ X ] [ Y ];
          board[ X ] [ Y ].setType( UNDEFINED );
          board[ moveX ] [  moveY  ] = tempChessPiece;
     }

Answer 1

I have got this code to work but it does not appear
to be very efficient to me as i dont recycle the
objects.
Any thoughts?The objects will be recycled by the garbage collector. It's very efficient so there's very little performance penalty in creating objects and releasing objects.
Still, another alternative is to represent an empty square with null. In that case the code becomes,
private static void makeMove( int selectedX, int selectedY, int moveToX, int moveToY ) {
   board[moveToY][moveToX] = board[selectedX][selectedY]; // piece to new position
   board[selectedX][selectedY] = null; // remove from old
}I don't know your exact design but that should work. It's kind of natural too. If a square is empty there's no piece object there at all. No new object has to be created and that explicit cast is gone.