- added the castling method

src/backend/MovePiece.java

@@ -173,6 +173,12 @@ public class MovePiece {
                 return true;
             }
         }
+        
+        // Castling move 
+        MovementCapabilities mc = new MovementCapabilities();
+        if (mc.castling(piece, x, y, board)) {
+        	return true;
+        }
         return false;
     }
     

src/backend/MovementCapabilities.java

@@ -50,11 +50,57 @@ public class MovementCapabilities {
 	
 	
 	public boolean castling(Piece king, int x, int y, Board board) {
-		if (king.getType()!= PieceType.King|| king.getdidMove()) {
+		if (king.getType()!= PieceType.King|| king.getDidMove()) {
 			return false;	
-			
 		}
 		
+		int currentX = king.getX();
+		int currentY = king.getY();
+		boolean isWhite = king.isWhite();  // getting coordinates and color of the king 
+		
+		
+		if (y != currentY) { // checking to see if the king has moved during the game yet 
+			return false;
+		}
+		
+		if (x==currentX+2) { // moving the king to the right of the rook AKA "kingside castling"
+			Piece rook = board.getPiece(7, currentY);
+			
+			// writing each condition separately instead of in the if loop for more clarity 
+			boolean isRook = rook != null && rook.getType()== PieceType.Rook; // check if rook exists
+			boolean rookMoved = !rook.getDidMove();	
+			boolean emptySpaceRight = board.getPiece(5, currentY)== null && board.getPiece(6, currentY)== null;
+			
+			if (isRook && rookMoved) {
+				if (emptySpaceRight) {
+					
+					board.movePiece(currentX, currentY, 6, currentY); // moving the king to ...
+					board.movePiece(7, currentY, 5, currentY); // moving the rook to ... 
+					
+					return true;	
+				}
+			}
+		}
+		
+		if (x==currentX-2) { // moving the king to the left of the rook AKA "queenside castling")
+			Piece rook = board.getPiece(0, currentY); 
+			
+			boolean isRook = rook != null && rook.getType()== PieceType.Rook;
+			boolean rookMoved = !rook.getDidMove();
+			boolean emptySpaceLeft = board.getPiece(3, currentY) == null && board.getPiece(2, currentY) == null && board.getPiece(1, currentY)== null;
+			
+			if (isRook && rookMoved) {
+				if (emptySpaceLeft) {
+					board.movePiece(currentX, currentY, 2, currentY); // moving king to...
+					board.movePiece(0,currentY,3,currentY); // moving rook to...
+					return true;
+				
+				}
+				
+			}
+		}
+		
+		
 		return false;
 	}
 }

src/backend/Piece.java

@@ -39,7 +39,7 @@ public class Piece {
 		return white;
 	}
 	
-	public boolean getdidMove() { // added getter 
+	public boolean getDidMove() { // added getter 
 		return didMove;
 		
 	}