Fixed memory leak, improved copy constructors

src/dev/kske/chess/board/Board.java

@@ -15,7 +15,7 @@ import dev.kske.chess.board.Piece.Type;
  * Created: <strong>01.07.2019</strong><br>
  * Author: <strong>Kai S. K. Engelbart</strong>
  */
-public class Board implements Cloneable {
+public class Board {
 
 	private Piece[][]						boardArr		= new Piece[8][8];
 	private Map<Color, Position>			kingPos			= new HashMap<>();
@@ -75,6 +75,30 @@ public class Board implements Cloneable {
 		initFromFEN(fen);
 	}
 
+	/**
+	 * Creates a copy of another {@link Board} instance.<br>
+	 * The created object is a deep copy, but does not contain any move history
+	 * apart from the current {@link MoveNode}.
+	 * 
+	 * @param other The {@link Board} instance to copy
+	 */
+	public Board(Board other) {
+		boardArr = new Piece[8][8];
+		for (int i = 0; i < 8; i++)
+			for (int j = 0; j < 8; j++) {
+				if (other.boardArr[i][j] == null) continue;
+				boardArr[i][j]			= (Piece) other.boardArr[i][j].clone();
+				boardArr[i][j].board	= this;
+			}
+
+		kingPos.putAll(other.kingPos);
+		Map<Type, Boolean> whiteCastling = new HashMap<>(other.castlingRights.get(Color.WHITE)),
+				blackCastling = new HashMap<>(other.castlingRights.get(Color.BLACK));
+		castlingRights.put(Color.WHITE, whiteCastling);
+		castlingRights.put(Color.BLACK, blackCastling);
+		log = new Log(other.log, false);
+	}
+
 	/**
 	 * Moves a piece across the board if the move is legal.
 	 * 
@@ -523,33 +547,6 @@ public class Board implements Cloneable {
 		return sb.toString();
 	}
 
-	/**
-	 * @return A new instance of this class with a shallow copy of both
-	 *         {@code kingPos} and {code boardArr}
-	 */
-	@Override
-	public Object clone() {
-		Board board = null;
-		try {
-			board = (Board) super.clone();
-		} catch (CloneNotSupportedException ex) {
-			ex.printStackTrace();
-		}
-		board.boardArr = new Piece[8][8];
-		for (int i = 0; i < 8; i++)
-			for (int j = 0; j < 8; j++) {
-				if (boardArr[i][j] == null) continue;
-				board.boardArr[i][j]		= (Piece) boardArr[i][j].clone();
-				board.boardArr[i][j].board	= board;
-			}
-
-		board.kingPos = new HashMap<>();
-		board.kingPos.putAll(kingPos);
-		board.log = new Log(log);
-
-		return board;
-	}
-
 	/**
 	 * @param pos The position from which to return a piece
 	 * @return The piece at the position

src/dev/kske/chess/board/Log.java

@@ -24,12 +24,15 @@ public class Log {
 	}
 
 	/**
-	 * Creates a partial deep copy of another {@link Log} instance which begins with
+	 * Creates a (partially deep) copy of another {@link Log} instance which begins
-	 * the current node.
+	 * with the current {@link MoveNode}.
 	 * 
 	 * @param other          The {@link Log} instance to copy
+	 * @param copyVariations If set to {@code true}, subsequent variations of the
+	 *                       current {@link MoveNode} are copied with the
+	 *                       {@link Log}
 	 */
-	public Log(Log other) {
+	public Log(Log other, boolean copyVariations) {
 		enPassant		= other.enPassant;
 		activeColor		= other.activeColor;
 		fullmoveCounter	= other.fullmoveCounter;
@@ -37,7 +40,7 @@ public class Log {
 
 		// The new root is the current node of the copied instance
 		if (!other.isEmpty()) {
-			root		= new MoveNode(other.current);
+			root		= new MoveNode(other.current, copyVariations);
 			root.parent	= null;
 			current		= root;
 		}
@@ -73,6 +76,7 @@ public class Log {
 	 */
 	public void removeLast() {
 		if (!isEmpty() && current.parent != null) {
+			current.parent.variations.remove(current);
 			current			= current.parent;
 			activeColor		= current.activeColor;
 			enPassant		= current.enPassant;
@@ -131,10 +135,10 @@ public class Log {
 		public final int		fullmoveCounter, halfmoveClock;
 
 		private MoveNode		parent;
-		private List<MoveNode>	variations	= new ArrayList<>();
+		private List<MoveNode>	variations;
 
 		/**
-		 * Creates a new {@link MoveNode}
+		 * Creates a new {@link MoveNode}.
 		 * 
 		 * @param move            The logged {@link Move}
 		 * @param capturedPiece   The {@link Piece} captures by the logged {@link Move}
@@ -155,19 +159,25 @@ public class Log {
 		}
 
 		/**
-		 * Creates a deep copy of another {@link MoveNode}.
+		 * Creates a (deep) copy of another {@link MoveNode}.
 		 * 
 		 * @param other          The {@link MoveNode} to copy
+		 * @param copyVariations When this is set to {@code true} a deep copy is
+		 *                       created, which
+		 *                       considers subsequent variations
 		 */
-		public MoveNode(MoveNode other) {
+		public MoveNode(MoveNode other, boolean copyVariations) {
 			this(other.move, other.capturedPiece, other.enPassant, other.activeColor, other.fullmoveCounter,
 					other.halfmoveClock);
+			if (copyVariations && other.variations != null) {
+				if (variations == null) variations = new ArrayList<>();
 				other.variations.forEach(variation -> {
-				MoveNode copy = new MoveNode(variation);
+					MoveNode copy = new MoveNode(variation, true);
 					copy.parent = this;
 					variations.add(copy);
 				});
 			}
+		}
 
 		/**
 		 * Adds another {@link MoveNode} as a child node.
@@ -175,10 +185,16 @@ public class Log {
 		 * @param variation The {@link MoveNode} to append to this {@link MoveNode}
 		 */
 		public void addVariation(MoveNode variation) {
+			if (variations == null) variations = new ArrayList<>();
 			if (!variations.contains(variation)) {
 				variations.add(variation);
 				variation.parent = this;
 			}
 		}
+
+		/**
+		 * @return A list of all variations associated with this {@link MoveNode}
+		 */
+		public List<MoveNode> getVariations() { return variations; }
 	}
 }

src/dev/kske/chess/game/Game.java

@@ -77,6 +77,9 @@ public class Game {
 			boardComponent.repaint();
 			overlayComponent.displayArrow(move);
 
+			// Run garbage collection
+			System.gc();
+
 			System.out.printf("%s: %s%n", player.color, move);
 			System.out.println("FEN: " + board.toFEN());
 			EventBus.getInstance().dispatch(new MoveEvent(move));

src/dev/kske/chess/game/NaturalPlayer.java

@@ -56,7 +56,7 @@ public class NaturalPlayer extends Player implements MouseListener {
 			pos = new Position(evt.getPoint().x / overlayComponent.getTileSize(),
 					evt.getPoint().y / overlayComponent.getTileSize());
 
-			Board board = (Board) NaturalPlayer.this.board.clone();
+			Board board = new Board(this.board);
 			if (board.get(pos) != null && board.get(pos).getColor() == color) {
 				List<Position> positions = board.getMoves(pos)
 					.stream()

src/dev/kske/chess/game/ai/AIPlayer.java

@@ -50,7 +50,7 @@ public class AIPlayer extends Player {
 			/*
 			 * Get a copy of the board and the available moves.
 			 */
-			Board		board	= (Board) AIPlayer.this.board.clone();
+			Board		board	= new Board(this.board);
 			List<Move>	moves	= board.getMoves(color);
 
 			/*
@@ -64,7 +64,7 @@ public class AIPlayer extends Player {
 			for (int i = 0; i < numThreads; i++) {
 				if (rem-- > 0) ++endIndex;
 				endIndex += step;
-				processors.add(new MoveProcessor((Board) board.clone(), moves.subList(beginIndex, endIndex), color,
+				processors.add(new MoveProcessor(new Board(board), moves.subList(beginIndex, endIndex), color,
 						maxDepth, alphaBetaThreshold));
 				beginIndex = endIndex;
 			}

test/dev/kske/chess/board/BoardTest.java

@@ -6,10 +6,7 @@ import static org.junit.Assert.assertNotSame;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
-import dev.kske.chess.board.Board;
-import dev.kske.chess.board.Move;
 import dev.kske.chess.board.Piece.Color;
-import dev.kske.chess.board.Queen;
 
 /**
  * Project: <strong>Chess</strong><br>
@@ -34,7 +31,7 @@ class BoardTest {
 	 */
 	@Test
 	void testClone() {
-		Board clone = (Board) board.clone();
+		Board clone = new Board(board);
 		assertNotSame(clone, board);
 		assertNotSame(clone.getBoardArr(), board.getBoardArr());
 

test/dev/kske/chess/board/LogTest.java

@@ -39,10 +39,16 @@ class LogTest {
 	 */
 	@Test
 	void testClone() {
-		Log other = new Log(log);
+		Log other = new Log(log, false);
 		log.setActiveColor(Color.WHITE);
 		other.setActiveColor(Color.BLACK);
-		assertNotEquals(other.getActiveColor(), log.getActiveColor());
+		assertNotEquals(log.getActiveColor(), other.getActiveColor());
+		log.add(Move.fromSAN("a2a4"), null, true);
+		log.add(Move.fromSAN("a4a5"), null, true);
+		other.add(Move.fromSAN("a2a4"), null, true);
+		other.add(Move.fromSAN("a4a5"), null, true);
+		assertNotEquals(log.getRoot(), other.getRoot());
+		assertNotEquals(log.getRoot().getVariations(), other.getRoot().getVariations());
 	}
 
 	/**