public void MakeMove(int r1, int c1, int r2, int c2) 
    {        
        this.cell[r2][c2] = this.cell[r1][c1];
        this.cell[r1][c1] = CellEntry.empty;
        
        // Promote To King
        if(this.cell[r2][c2].equals(CellEntry.white) && r2==rows-1){
            this.cell[r2][c2] = CellEntry.whiteKing;
        }
        else if(this.cell[r2][c2].equals(CellEntry.black) && r2==0){
            this.cell[r2][c2] = CellEntry.blackKing;
        }
    }