Merge pull request #16 from CyB3RC0nN0R/f/pgn_save

Implemented game serialization to the PGN format

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

@@ -6,8 +6,6 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
-import java.util.regex.Matcher;
-import java.util.regex.Pattern;
 
 import dev.kske.chess.board.Piece.Color;
 
@@ -36,9 +34,9 @@ public class Board {
 	 * apart from the current {@link MoveNode}.
 	 *
 	 * @param other The {@link Board} instance to copy
+	 * @param copyVariations TODO
 	 */
-	public Board(Board other) {
+	public Board(Board other, boolean copyVariations) {
-		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;
@@ -47,7 +45,11 @@ public class Board {
 			}
 
 		kingPos.putAll(other.kingPos);
-		log = new Log(other.log, false);
+		log = new Log(other.log, copyVariations);
+
+		// Synchronize the current move node with the board
+		while (log.getLast().hasVariations())
+			log.selectNextNode(0);
 	}
 
 	/**
@@ -98,83 +100,7 @@ public class Board {
 	 * @param sanMove The move to execute in SAN (Standard Algebraic Notation)
 	 */
 	public void move(String sanMove) {
-		Map<String, Pattern> patterns = new HashMap<>();
+		move(Move.fromSAN(sanMove, this));
-		patterns.put("pieceMove",
-				Pattern.compile(
-						"^(?<pieceType>[NBRQK])(?:(?<fromFile>[a-h])|(?<fromRank>[1-8])|(?<fromSquare>[a-h][1-8]))?x?(?<toSquare>[a-h][1-8])(?:\\+{0,2}|\\#)$"));
-		patterns.put("pawnCapture",
-				Pattern.compile("^(?<fromFile>[a-h])(?<fromRank>[1-8])?x(?<toSquare>[a-h][1-8])(?<promotedTo>[NBRQ])?(?:\\+{0,2}|\\#)?$"));
-		patterns.put("pawnPush", Pattern.compile("^(?<toSquare>[a-h][1-8])(?<promotedTo>[NBRQ])?(?:\\+{0,2}|\\#)$"));
-		patterns.put("castling", Pattern.compile("^(?<queenside>O-O-O)|(?<kingside>O-O)(?:\\+{0,2}|\\#)?$"));
-
-		patterns.forEach((patternName, pattern) -> {
-			Matcher m = pattern.matcher(sanMove);
-			if (m.find()) {
-				Position	pos		= null, dest = null;
-				Move		move	= null;
-				switch (patternName) {
-					case "pieceMove":
-						dest = Position.fromLAN(m.group("toSquare"));
-						if (m.group("fromSquare") != null) pos = Position.fromLAN(m.group("fromSquare"));
-						else {
-							Class<? extends Piece>	pieceClass	= Piece.fromFirstChar(m.group("pieceType").charAt(0));
-							char					file;
-							int						rank;
-							if (m.group("fromFile") != null) {
-								file	= m.group("fromFile").charAt(0);
-								rank	= get(pieceClass, file);
-								pos		= Position.fromLAN(String.format("%c%d", file, rank));
-							} else if (m.group("fromRank") != null) {
-								rank	= Integer.parseInt(m.group("fromRank").substring(0, 1));
-								file	= get(pieceClass, rank);
-								pos		= Position.fromLAN(String.format("%c%d", file, rank));
-							} else pos = get(pieceClass, dest);
-						}
-						move = new Move(pos, dest);
-						break;
-					case "pawnCapture":
-						char file = m.group("fromFile").charAt(0);
-						int rank = m.group("fromRank") == null ? get(Pawn.class, file) : Integer.parseInt(m.group("fromRank"));
-
-						dest = Position.fromLAN(m.group("toSquare"));
-						pos = Position.fromLAN(String.format("%c%d", file, rank));
-
-						if (m.group("promotedTo") != null) {
-							try {
-								move = new PawnPromotion(pos, dest, Piece.fromFirstChar(m.group("promotedTo").charAt(0)));
-							} catch (NoSuchMethodException | SecurityException | IllegalArgumentException e) {
-								e.printStackTrace();
-							}
-						} else move = new Move(pos, dest);
-						break;
-					case "pawnPush":
-						dest = Position.fromLAN(m.group("toSquare"));
-						int step = log.getActiveColor() == Color.WHITE ? 1 : -1;
-
-						// One step forward
-						if (boardArr[dest.x][dest.y + step] != null) pos = new Position(dest.x, dest.y + step);
-
-						// Double step forward
-						else pos = new Position(dest.x, dest.y + 2 * step);
-
-						if (m.group("promotedTo") != null) {
-							try {
-								move = new PawnPromotion(pos, dest, Piece.fromFirstChar(m.group("promotedTo").charAt(0)));
-							} catch (NoSuchMethodException | SecurityException | IllegalArgumentException e) {
-								e.printStackTrace();
-							}
-						} else move = new Move(pos, dest);
-						break;
-					case "castling":
-						pos = new Position(4, log.getActiveColor() == Color.WHITE ? 7 : 0);
-						dest = new Position(m.group("kingside") != null ? 6 : 2, pos.y);
-						move = new Castling(pos, dest);
-						break;
-				}
-				move(move);
-				return;
-			}
-		});
 	}
 
 	/**

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

@@ -32,4 +32,13 @@ public class Castling extends Move {
 		super.revert(board, capturedPiece);
 		rookMove.revert(board, null);
 	}
+
+	/**
+	 * @return {@code O-O-O} for a queenside castling or {@code O-O} for a kingside
+	 *         castling
+	 */
+	@Override
+	public String toSAN(Board board) {
+		return rookMove.pos.x == 0 ? "O-O-O" : "O-O";
+	}
 }

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

@@ -43,12 +43,17 @@ public class Log implements Iterable<MoveNode> {
 
 		// The new root is the current node of the copied instance
 		if (!other.isEmpty()) {
-			root = new MoveNode(other.current, copyVariations);
+			root = new MoveNode(other.root, copyVariations);
 			root.setParent(null);
 			current = root;
 		}
 	}
 
+	/**
+	 * @return an iterator over all {@link MoveNode} objects that are either the
+	 *         root node or a first variation of another node, starting from the
+	 *         root node
+	 */
 	@Override
 	public Iterator<MoveNode> iterator() {
 		return new Iterator<MoveNode>() {
@@ -98,7 +103,7 @@ public class Log implements Iterable<MoveNode> {
 	}
 
 	/**
-	 * Removed the last move from the log and adjusts its state to the previous
+	 * Removes the last move from the log and adjusts its state to the previous
 	 * move.
 	 */
 	public void removeLast() {
@@ -109,8 +114,14 @@ public class Log implements Iterable<MoveNode> {
 		} else reset();
 	}
 
+	/**
+	 * @return {@code true} if the root node exists
+	 */
 	public boolean isEmpty() { return root == null; }
 
+	/**
+	 * @return {@code true} if the current node has a parent node
+	 */
 	public boolean hasParent() { return !isEmpty() && current.hasParent(); }
 
 	/**
@@ -159,6 +170,10 @@ public class Log implements Iterable<MoveNode> {
 		}
 	}
 
+	/**
+	 * Sets the active color, castling rights, en passant target square, fullmove
+	 * number and halfmove clock to those of the current {@link MoveNode}.
+	 */
 	private void update() {
 		activeColor		= current.activeColor;
 		castlingRights	= current.castlingRights.clone();
@@ -167,6 +182,15 @@ public class Log implements Iterable<MoveNode> {
 		halfmoveClock	= current.halfmoveClock;
 	}
 
+	/**
+	 * Removed the castling rights bound to a rook or king for the rest of the game.
+	 * This method should be called once the piece has been moved, as a castling
+	 * move involving this piece is forbidden afterwards.
+	 *
+	 * @param piece           the rook or king to disable the castling rights for
+	 * @param initialPosition the initial position of the piece during the start of
+	 *                        the game
+	 */
 	private void disableCastlingRights(Piece piece, Position initialPosition) {
 		// Kingside
 		if (piece instanceof King || piece instanceof Rook && initialPosition.x == 7)
@@ -220,7 +244,7 @@ public class Log implements Iterable<MoveNode> {
 
 	public int getFullmoveNumber() { return fullmoveNumber; }
 
-	public void setFullmoveNumber(int fullmoveCounter) { this.fullmoveNumber = fullmoveCounter; }
+	public void setFullmoveNumber(int fullmoveNumber) { this.fullmoveNumber = fullmoveNumber; }
 
 	public int getHalfmoveClock() { return halfmoveClock; }
 

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

@@ -1,6 +1,12 @@
 package dev.kske.chess.board;
 
+import java.util.HashMap;
+import java.util.Map;
 import java.util.Objects;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import dev.kske.chess.board.Piece.Color;
 
 /**
  * Project: <strong>Chess</strong><br>
@@ -44,7 +50,7 @@ public class Move {
 		if (move.length() == 5) {
 			try {
 				return new PawnPromotion(pos, dest, Piece.fromFirstChar(move.charAt(4)));
-			} catch (NoSuchMethodException | SecurityException | IllegalArgumentException e) {
+			} catch (Exception e) {
 				e.printStackTrace();
 				return null;
 			}
@@ -53,6 +59,116 @@ public class Move {
 
 	public String toLAN() { return getPos().toLAN() + getDest().toLAN(); }
 
+	/**
+	 * Converts a move string from standard algebraic notation to a {@link Move}
+	 * object.
+	 *
+	 * @param sanMove the move string to convert from
+	 * @param board   the board on which the move has to be executed
+	 * @return the converted {@link Move} object
+	 */
+	public static Move fromSAN(String sanMove, Board board) {
+		Map<String, Pattern> patterns = new HashMap<>();
+		patterns.put("pieceMove",
+				Pattern.compile(
+						"^(?<pieceType>[NBRQK])(?:(?<fromFile>[a-h])|(?<fromRank>[1-8])|(?<fromSquare>[a-h][1-8]))?x?(?<toSquare>[a-h][1-8])(?:\\+{0,2}|\\#)$"));
+		patterns.put("pawnCapture",
+				Pattern.compile("^(?<fromFile>[a-h])(?<fromRank>[1-8])?x(?<toSquare>[a-h][1-8])(?<promotedTo>[NBRQ])?(?:\\+{0,2}|\\#)?$"));
+		patterns.put("pawnPush", Pattern.compile("^(?<toSquare>[a-h][1-8])(?<promotedTo>[NBRQ])?(?:\\+{0,2}|\\#)$"));
+		patterns.put("castling", Pattern.compile("^(?<queenside>O-O-O)|(?<kingside>O-O)(?:\\+{0,2}|\\#)?$"));
+
+		for (Map.Entry<String, Pattern> entry : patterns.entrySet()) {
+			Matcher m = entry.getValue().matcher(sanMove);
+			if (m.find()) {
+				Position	pos		= null, dest = null;
+				Move		move	= null;
+				switch (entry.getKey()) {
+					case "pieceMove":
+						dest = Position.fromLAN(m.group("toSquare"));
+						if (m.group("fromSquare") != null) pos = Position.fromLAN(m.group("fromSquare"));
+						else {
+							Class<? extends Piece>	pieceClass	= Piece.fromFirstChar(m.group("pieceType").charAt(0));
+							char					file;
+							int						rank;
+							if (m.group("fromFile") != null) {
+								file	= m.group("fromFile").charAt(0);
+								rank	= board.get(pieceClass, file);
+								pos		= Position.fromLAN(String.format("%c%d", file, rank));
+							} else if (m.group("fromRank") != null) {
+								rank	= Integer.parseInt(m.group("fromRank").substring(0, 1));
+								file	= board.get(pieceClass, rank);
+								pos		= Position.fromLAN(String.format("%c%d", file, rank));
+							} else pos = board.get(pieceClass, dest);
+						}
+						move = new Move(pos, dest);
+						break;
+					case "pawnCapture":
+						char file = m.group("fromFile").charAt(0);
+						int rank = m.group("fromRank") == null ? board.get(Pawn.class, file) : Integer.parseInt(m.group("fromRank"));
+
+						dest = Position.fromLAN(m.group("toSquare"));
+						pos = Position.fromLAN(String.format("%c%d", file, rank));
+
+						if (m.group("promotedTo") != null) {
+							try {
+								move = new PawnPromotion(pos, dest, Piece.fromFirstChar(m.group("promotedTo").charAt(0)));
+							} catch (Exception e) {
+								e.printStackTrace();
+							}
+						} else move = new Move(pos, dest);
+						break;
+					case "pawnPush":
+						dest = Position.fromLAN(m.group("toSquare"));
+						int step = board.getLog().getActiveColor() == Color.WHITE ? 1 : -1;
+
+						// One step forward
+						if (board.getBoardArr()[dest.x][dest.y + step] != null) pos = new Position(dest.x, dest.y + step);
+
+						// Double step forward
+						else pos = new Position(dest.x, dest.y + 2 * step);
+
+						if (m.group("promotedTo") != null) {
+							try {
+								move = new PawnPromotion(pos, dest, Piece.fromFirstChar(m.group("promotedTo").charAt(0)));
+							} catch (Exception e) {
+								e.printStackTrace();
+							}
+						} else move = new Move(pos, dest);
+						break;
+					case "castling":
+						pos = new Position(4, board.getLog().getActiveColor() == Color.WHITE ? 7 : 0);
+						dest = new Position(m.group("kingside") != null ? 6 : 2, pos.y);
+						move = new Castling(pos, dest);
+						break;
+				}
+				return move;
+			}
+		}
+		return null;
+	}
+
+	public String toSAN(Board board) {
+		final Piece		piece	= board.get(pos);
+		StringBuilder	sb		= new StringBuilder(8);
+
+		// Piece symbol
+		if(!(piece instanceof Pawn))
+			sb.append(Character.toUpperCase(piece.firstChar()));
+
+		// Position
+		// TODO: Deconstruct position into optional file or rank
+		// Omit position if the move is a pawn push
+		if (!(piece instanceof Pawn && xDist == 0)) sb.append(pos.toLAN());
+
+		// Capture indicator
+		if (board.get(dest) != null) sb.append('x');
+
+		// Destination
+		sb.append(dest.toLAN());
+
+		return sb.toString();
+	}
+
 	public boolean isHorizontal() { return getyDist() == 0; }
 
 	public boolean isVertical() { return getxDist() == 0; }

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

@@ -64,11 +64,11 @@ public class MoveNode {
 				other.fullmoveCounter, other.halfmoveClock);
 		if (copyVariations && other.variations != null) {
 			if (variations == null) variations = new ArrayList<>();
-			other.variations.forEach(variation -> {
+			for (MoveNode variation : other.variations) {
 				MoveNode copy = new MoveNode(variation, true);
 				copy.parent = this;
 				variations.add(copy);
-			});
+			}
 		}
 	}
 

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

@@ -74,7 +74,7 @@ public class Pawn extends Piece {
 					moves.add(new PawnPromotion(pos, dest, Rook.class));
 					moves.add(new PawnPromotion(pos, dest, Knight.class));
 					moves.add(new PawnPromotion(pos, dest, Bishop.class));
-				} catch (NoSuchMethodException | SecurityException | IllegalArgumentException e) {
+				} catch (Exception e) {
 					e.printStackTrace();
 				}
 			} else moves.add(move);

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

@@ -16,21 +16,23 @@ import dev.kske.chess.board.Piece.Color;
  */
 public class PawnPromotion extends Move {
 
-	private final Class<? extends Piece>		promotionPieceClass;
 	private final Constructor<? extends Piece>	promotionPieceConstructor;
+	private final char							promotionPieceChar;
 
-	public PawnPromotion(Position pos, Position dest, Class<? extends Piece> promotionPieceClass) throws NoSuchMethodException, SecurityException {
+	public PawnPromotion(Position pos, Position dest, Class<? extends Piece> promotionPieceClass)
+			throws ReflectiveOperationException, RuntimeException {
 		super(pos, dest);
-		this.promotionPieceClass = promotionPieceClass;
 
 		// Cache piece constructor
 		promotionPieceConstructor = promotionPieceClass.getDeclaredConstructor(Color.class, Board.class);
 		promotionPieceConstructor.setAccessible(true);
+
+		// Get piece char
+		promotionPieceChar = (char) promotionPieceClass.getMethod("firstChar").invoke(promotionPieceConstructor.newInstance(null, null));
 	}
 
 	public PawnPromotion(int xPos, int yPos, int xDest, int yDest, Class<? extends Piece> promotionPiece)
-			throws NoSuchMethodException, SecurityException, IllegalAccessException, IllegalArgumentException, InvocationTargetException,
+			throws ReflectiveOperationException, RuntimeException {
-			InstantiationException {
 		this(new Position(xPos, yPos), new Position(xDest, yDest), promotionPiece);
 	}
 
@@ -51,22 +53,19 @@ public class PawnPromotion extends Move {
 	}
 
 	@Override
-	public String toLAN() {
+	public String toLAN() { return pos.toLAN() + dest.toLAN() + promotionPieceChar; }
-		char promotionPieceChar = '-';
+
-		try {
+	@Override
-			promotionPieceChar = (char) promotionPieceClass.getMethod("firstChar").invoke(promotionPieceConstructor.newInstance(null, null));
+	public String toSAN(Board board) {
-		} catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException | NoSuchMethodException | SecurityException
+		String san = super.toSAN(board);
-				| InstantiationException e) {
+		return san + Character.toUpperCase(promotionPieceChar);
-			e.printStackTrace();
-		}
-		return pos.toLAN() + dest.toLAN() + promotionPieceChar;
 	}
 
 	@Override
 	public int hashCode() {
 		final int	prime	= 31;
 		int			result	= super.hashCode();
-		result = prime * result + Objects.hash(promotionPieceClass);
+		result = prime * result + Objects.hash(promotionPieceChar, promotionPieceConstructor);
 		return result;
 	}
 
@@ -74,8 +73,8 @@ public class PawnPromotion extends Move {
 	public boolean equals(Object obj) {
 		if (this == obj) return true;
 		if (!super.equals(obj)) return false;
-		if (getClass() != obj.getClass()) return false;
+		if (!(obj instanceof PawnPromotion)) return false;
 		PawnPromotion other = (PawnPromotion) obj;
-		return Objects.equals(promotionPieceClass, other.promotionPieceClass);
+		return promotionPieceChar == other.promotionPieceChar && Objects.equals(promotionPieceConstructor, other.promotionPieceConstructor);
 	}
 }

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

@@ -52,7 +52,7 @@ public class AIPlayer extends Player {
 			/*
 			 * Get a copy of the board and the available moves.
 			 */
-			Board		board	= new Board(this.board);
+			Board		board	= new Board(this.board, false);
 			List<Move>	moves	= board.getMoves(color);
 
 			/*
@@ -66,7 +66,7 @@ public class AIPlayer extends Player {
 			for (int i = 0; i < numThreads; i++) {
 				if (rem-- > 0) ++endIndex;
 				endIndex += step;
-				processors.add(new MoveProcessor(new Board(board), moves.subList(beginIndex, endIndex), color,
+				processors.add(new MoveProcessor(new Board(board, false), moves.subList(beginIndex, endIndex), color,
 						maxDepth, alphaBetaThreshold));
 				beginIndex = endIndex;
 			}

src/dev/kske/chess/pgn/PGNDatabase.java

@@ -2,6 +2,8 @@ package dev.kske.chess.pgn;
 
 import java.io.File;
 import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.PrintWriter;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Scanner;
@@ -12,21 +14,42 @@ import dev.kske.chess.exception.ChessException;
  * Project: <strong>Chess</strong><br>
  * File: <strong>PGNDatabase.java</strong><br>
  * Created: <strong>4 Oct 2019</strong><br>
+ * <br>
+ * Contains a series of {@link PGNGame} objects that can be stored inside a PGN
+ * file.
  * 
  * @since Chess v0.5-alpha
  * @author Kai S. K. Engelbart
  */
 public class PGNDatabase {
 
-	private final List<PGNGame>	games	= new ArrayList<>();
+	private final List<PGNGame> games = new ArrayList<>();
 
+	/**
+	 * Loads PGN games from a file.
+	 * 
+	 * @param pgnFile the file to load the games from
+	 * @throws FileNotFoundException if the specified file is not found
+	 * @throws ChessException        if an error occurs while parsing the file
+	 */
 	public void load(File pgnFile) throws FileNotFoundException, ChessException {
-		try (Scanner sc = new Scanner(pgnFile)) {
+		Scanner sc = new Scanner(pgnFile);
-			while (sc.hasNext())
+		while (sc.hasNext())
-				games.add(PGNGame.parse(sc));
+			games.add(PGNGame.parse(sc));
-		} catch (FileNotFoundException | ChessException e) {
+		sc.close();
-			throw e;
+	}
-		}
+
+	/**
+	 * Saves PGN games to a file.
+	 * 
+	 * @param pgnFile the file to save the games to.
+	 * @throws IOException if the file could not be created
+	 */
+	public void save(File pgnFile) throws IOException {
+		pgnFile.getParentFile().mkdirs();
+		PrintWriter pw = new PrintWriter(pgnFile);
+		games.forEach(g -> g.writePGN(pw));
+		pw.close();
 	}
 
 	public List<PGNGame> getGames() { return games; }

src/dev/kske/chess/pgn/PGNGame.java

@@ -1,6 +1,10 @@
 package dev.kske.chess.pgn;
 
+import java.io.PrintWriter;
+import java.util.ArrayList;
+import java.util.Collections;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 import java.util.Scanner;
 import java.util.regex.MatchResult;
@@ -8,6 +12,8 @@ import java.util.regex.Pattern;
 
 import dev.kske.chess.board.Board;
 import dev.kske.chess.board.FENString;
+import dev.kske.chess.board.Move;
+import dev.kske.chess.board.Piece.Color;
 import dev.kske.chess.exception.ChessException;
 
 /**
@@ -21,7 +27,11 @@ import dev.kske.chess.exception.ChessException;
 public class PGNGame {
 
 	private final Map<String, String>	tagPairs	= new HashMap<>(7);
-	private final Board					board		= new Board();
+	private final Board					board;
+
+	public PGNGame() { board = new Board(); }
+
+	public PGNGame(Board board) { this.board = board; }
 
 	public static PGNGame parse(Scanner sc) throws ChessException {
 		PGNGame game = new PGNGame();
@@ -62,6 +72,45 @@ public class PGNGame {
 		return game;
 	}
 
+	public void writePGN(PrintWriter pw) {
+		// Set the unknown result tag if no result tag is specified
+		tagPairs.putIfAbsent("Result", "*");
+
+		// Write tag pairs
+		tagPairs.forEach((k, v) -> pw.printf("[%s \"%s\"]%n", k, v));
+
+		// Insert newline if tags were printed
+		if (!tagPairs.isEmpty()) pw.println();
+
+		if (!board.getLog().isEmpty()) {
+			// Collect SAN moves
+			Board			clone	= new Board(board, true);
+			List<String>	chunks	= new ArrayList<>();
+			boolean			flag	= true;
+			while (flag) {
+				Move move = clone.getLog().getLast().move;
+				flag = clone.getLog().hasParent();
+				clone.revert();
+				String chunk = clone.getLog().getActiveColor() == Color.WHITE ? String.format(" %d. ", clone.getLog().getFullmoveNumber()) : " ";
+				chunk += move.toSAN(clone);
+				chunks.add(chunk);
+			}
+			Collections.reverse(chunks);
+
+			// Write movetext
+			String line = "";
+			for (String chunk : chunks)
+				if (line.length() + chunk.length() <= 80) line += chunk;
+				else {
+					pw.println(line);
+					line = chunk;
+				}
+			if (!line.isEmpty()) pw.println(line);
+		}
+		// Write game termination marker
+		pw.print(tagPairs.get("Result"));
+	}
+
 	public String getTag(String tagName) { return tagPairs.get(tagName); }
 
 	public boolean hasTag(String tagName) { return tagPairs.containsKey(tagName); }

src/dev/kske/chess/ui/DialogUtil.java

@@ -5,6 +5,7 @@ import java.awt.Font;
 import java.io.File;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.List;
 import java.util.function.BiConsumer;
 import java.util.function.Consumer;
@@ -15,7 +16,7 @@ import javax.swing.JFileChooser;
 import javax.swing.JLabel;
 import javax.swing.JOptionPane;
 import javax.swing.JPanel;
-import javax.swing.filechooser.FileFilter;
+import javax.swing.filechooser.FileNameExtensionFilter;
 
 import dev.kske.chess.io.EngineUtil;
 
@@ -31,27 +32,24 @@ public class DialogUtil {
 
 	private DialogUtil() {}
 
-	public static void showFileSelectionDialog(Component parent, Consumer<List<File>> action) {
+	public static void showFileSelectionDialog(Component parent, Consumer<List<File>> action, Collection<FileNameExtensionFilter> filters) {
 		JFileChooser fileChooser = new JFileChooser();
 		fileChooser.setCurrentDirectory(new File(System.getProperty("user.home")));
 		fileChooser.setAcceptAllFileFilterUsed(false);
-		fileChooser.addChoosableFileFilter(new FileFilter() {
+		filters.forEach(fileChooser::addChoosableFileFilter);
-
-			@Override
-			public boolean accept(File f) {
-				int dotIndex = f.getName().lastIndexOf('.');
-				if (dotIndex >= 0) {
-					String extension = f.getName().substring(dotIndex).toLowerCase();
-					return extension.equals(".fen") || extension.equals(".pgn");
-				} else return f.isDirectory();
-			}
-
-			@Override
-			public String getDescription() { return "FEN and PGN files"; }
-		});
 		if (fileChooser.showOpenDialog(parent) == JFileChooser.APPROVE_OPTION) action.accept(Arrays.asList(fileChooser.getSelectedFile()));
 	}
 
+	public static void showFileSaveDialog(Component parent, Consumer<File> action, Collection<FileNameExtensionFilter> filters) {
+		JFileChooser fileChooser = new JFileChooser();
+		fileChooser.setCurrentDirectory(new File(System.getProperty("user.home")));
+		fileChooser.setAcceptAllFileFilterUsed(false);
+		filters.forEach(fileChooser::addChoosableFileFilter);
+		if (fileChooser.showSaveDialog(parent) == JFileChooser.APPROVE_OPTION) action.accept(
+				new File(fileChooser.getSelectedFile().getAbsolutePath() + "."
+						+ ((FileNameExtensionFilter) fileChooser.getFileFilter()).getExtensions()[0]));
+	}
+
 	public static void showGameConfigurationDialog(Component parent, BiConsumer<String, String> action) {
 		JPanel dialogPanel = new JPanel();
 
@@ -64,7 +62,7 @@ public class DialogUtil {
 		dialogPanel.add(lblWhite);
 
 		JComboBox<Object> cbWhite = new JComboBox<>();
-		cbWhite.setModel(new DefaultComboBoxModel<Object>(options.toArray()));
+		cbWhite.setModel(new DefaultComboBoxModel<>(options.toArray()));
 		cbWhite.setBounds(98, 9, 159, 22);
 		dialogPanel.add(cbWhite);
 
@@ -74,7 +72,7 @@ public class DialogUtil {
 		dialogPanel.add(lblBlack);
 
 		JComboBox<Object> cbBlack = new JComboBox<>();
-		cbBlack.setModel(new DefaultComboBoxModel<Object>(options.toArray()));
+		cbBlack.setModel(new DefaultComboBoxModel<>(options.toArray()));
 		cbBlack.setBounds(98, 36, 159, 22);
 		dialogPanel.add(cbBlack);
 

src/dev/kske/chess/ui/MainWindow.java

@@ -1,9 +1,11 @@
 package dev.kske.chess.ui;
 
+import java.awt.Desktop;
 import java.awt.EventQueue;
 import java.awt.Toolkit;
 import java.awt.dnd.DropTarget;
 import java.io.File;
+import java.io.IOException;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.util.List;
@@ -164,4 +166,30 @@ public class MainWindow extends JFrame {
 			}
 		});
 	}
+
+	public void saveFile(File file) {
+		final int		dotIndex	= file.getName().lastIndexOf('.');
+		final String	extension	= file.getName().substring(dotIndex).toLowerCase();
+
+		if (extension.equals(".pgn")) try {
+			PGNGame pgnGame = new PGNGame(getSelectedGamePane().getGame().getBoard());
+			pgnGame.setTag("Event", tabbedPane.getTitleAt(tabbedPane.getSelectedIndex()));
+			pgnGame.setTag("Result", "*");
+			PGNDatabase pgnDB = new PGNDatabase();
+			pgnDB.getGames().add(pgnGame);
+			pgnDB.save(file);
+
+			if (JOptionPane.showConfirmDialog(this,
+					"Game export finished. Do you want to view the created file?",
+					"Game export finished",
+					JOptionPane.YES_NO_OPTION) == JOptionPane.YES_OPTION)
+				Desktop.getDesktop().open(file);
+		} catch (IOException e) {
+			e.printStackTrace();
+			JOptionPane.showMessageDialog(this,
+					"Failed to save the file " + file.getName() + ": " + e.toString(),
+					"File saving error",
+					JOptionPane.ERROR_MESSAGE);
+		}
+	}
 }

src/dev/kske/chess/ui/MenuBar.java

@@ -2,11 +2,13 @@ package dev.kske.chess.ui;
 
 import java.awt.Toolkit;
 import java.awt.datatransfer.StringSelection;
+import java.util.Arrays;
 
 import javax.swing.JMenu;
 import javax.swing.JMenuBar;
 import javax.swing.JMenuItem;
 import javax.swing.JOptionPane;
+import javax.swing.filechooser.FileNameExtensionFilter;
 
 import dev.kske.chess.board.FENString;
 import dev.kske.chess.exception.ChessException;
@@ -48,9 +50,18 @@ public class MenuBar extends JMenuBar {
 		gameMenu.add(newGameMenuItem);
 
 		JMenuItem loadFileMenu = new JMenuItem("Load game file");
-		loadFileMenu.addActionListener((evt) -> DialogUtil.showFileSelectionDialog(mainWindow, mainWindow::loadFiles));
+		loadFileMenu.addActionListener((evt) -> DialogUtil
+			.showFileSelectionDialog(mainWindow,
+					mainWindow::loadFiles,
+					Arrays.asList(new FileNameExtensionFilter("FEN and PGN files", "fen", "pgn"))));
 		gameMenu.add(loadFileMenu);
 
+		JMenuItem saveFileMenu = new JMenuItem("Save game file");
+		saveFileMenu
+			.addActionListener((evt) -> DialogUtil
+				.showFileSaveDialog(mainWindow, mainWindow::saveFile, Arrays.asList(new FileNameExtensionFilter("PGN file", "pgn"))));
+		gameMenu.add(saveFileMenu);
+
 		add(gameMenu);
 		newGameMenuItem.doClick();
 	}

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

@@ -31,7 +31,7 @@ class BoardTest {
 	 */
 	@Test
 	void testClone() {
-		Board clone = new Board(board);
+		Board clone = new Board(board, false);
 		assertNotSame(clone, board);
 		assertNotSame(clone.getBoardArr(), board.getBoardArr());