Refactor for efficiency and concise code

* Change player map implentation in Game to EnumMap
* Add proper toString methods to Piece and MoveNode
* Compact code in MainWindow
* Synchronize methods in Game

.classpath

@@ -13,6 +13,10 @@
 		</attributes>
 	</classpathentry>
 	<classpathentry kind="con" path="org.eclipse.jdt.junit.JUNIT_CONTAINER/5"/>
-	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.8"/>
+	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.8">
+		<attributes>
+			<attribute name="module" value="true"/>
+		</attributes>
+	</classpathentry>
 	<classpathentry kind="output" path="bin"/>
 </classpath>

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

@@ -17,7 +17,7 @@ import dev.kske.chess.event.MoveEvent;
 public class Board {
 
 	private Piece[][]				boardArr	= new Piece[8][8];
-	private Map<Color, Position>	kingPos		= new HashMap<>();
+	private Map<Color, Position>	kingPos		= new EnumMap<>(Color.class);
 	private Log						log			= new Log();
 
 	/**

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

@@ -158,6 +158,18 @@ public class MoveNode {
 	 */
 	public boolean hasParent() { return parent != null; }
 
+	@Override
+	public String toString() {
+		return String.format("MoveNode[move=%s,capturedPiece=%s,castlingRights=%s,enPassant=%s,activeColor=%s,fullmoveCounter=%d,halfmoveClock=%d]",
+				move,
+				capturedPiece,
+				Arrays.toString(castlingRights),
+				enPassant,
+				activeColor,
+				fullmoveCounter,
+				halfmoveClock);
+	}
+
 	@Override
 	public int hashCode() {
 		final int	prime	= 31;

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

@@ -98,7 +98,7 @@ public abstract class Piece implements Cloneable {
 	}
 
 	@Override
-	public String toString() { return getClass().getSimpleName(); }
+	public String toString() { return String.format("%s[color=%s]", getClass().getSimpleName(), color); }
 
 	@Override
 	public int hashCode() { return Objects.hash(color); }
@@ -122,7 +122,7 @@ public abstract class Piece implements Cloneable {
 	 * @return The first character of this {@link Piece} in algebraic notation and
 	 *         lower case
 	 */
-	public char firstChar() { return Character.toLowerCase(toString().charAt(0)); }
+	public char firstChar() { return Character.toLowerCase(getClass().getSimpleName().charAt(0)); }
 
 	/**
 	 * @param firstChar the first character of a piece's name

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

@@ -1,6 +1,6 @@
 package dev.kske.chess.game;
 
-import java.util.HashMap;
+import java.util.EnumMap;
 import java.util.Map;
 
 import javax.swing.JOptionPane;
@@ -29,7 +29,7 @@ import dev.kske.chess.ui.OverlayComponent;
  */
 public class Game {
 
-	private Map<Color, Player>	players	= new HashMap<>(2);
+	private Map<Color, Player>	players	= new EnumMap<>(Color.class);
 	private Board				board;
 	private OverlayComponent	overlayComponent;
 	private BoardComponent		boardComponent;
@@ -69,9 +69,6 @@ public class Game {
 		// Initialize players
 		players.put(Color.WHITE, getPlayer(whiteName, Color.WHITE));
 		players.put(Color.BLACK, getPlayer(blackName, Color.BLACK));
-
-		// Initialize the game variable in each player
-		players.values().forEach(player -> player.setGame(this));
 	}
 
 	/**
@@ -88,12 +85,12 @@ public class Game {
 	private Player getPlayer(String name, Color color) {
 		switch (name) {
 			case "Natural Player":
-				return new NaturalPlayer(color, overlayComponent);
+				return new NaturalPlayer(this, color, overlayComponent);
 			case "AI Player":
-				return new AIPlayer(color, 4, -10);
+				return new AIPlayer(this, color, 4, -10);
 			default:
 				for (EngineInfo info : EngineUtil.getEngineInfos())
-					if (info.name.equals(name)) return new UCIPlayer(color, info.path);
+					if (info.name.equals(name)) return new UCIPlayer(this, color, info.path);
 				System.err.println("Invalid player name: " + name);
 				return null;
 		}
@@ -107,7 +104,7 @@ public class Game {
 	 * @param player the player who generated the move
 	 * @param move   the generated move
 	 */
-	public void onMove(Player player, Move move) {
+	public synchronized void onMove(Player player, Move move) {
 		if (board.getPos(move).getColor() == player.color && board.attemptMove(move)) {
 
 			// Redraw
@@ -138,7 +135,7 @@ public class Game {
 	 * Starts the game by requesting a move from the player of the currently active
 	 * color.
 	 */
-	public void start() {
+	public synchronized void start() {
 		EventBus.getInstance().dispatch(new GameStartEvent(this));
 		players.get(board.getLog().getActiveColor()).requestMove();
 	}
@@ -147,7 +144,7 @@ public class Game {
 	 * Cancels move calculations, initializes the default position and clears the
 	 * {@link OverlayComponent}.
 	 */
-	public void reset() {
+	public synchronized void reset() {
 		players.values().forEach(Player::cancelMove);
 		board.initDefaultPositions();
 		boardComponent.repaint();
@@ -158,12 +155,12 @@ public class Game {
 	/**
 	 * Stops the game by disconnecting its players from the UI.
 	 */
-	public void stop() { players.values().forEach(Player::disconnect); }
+	public synchronized void stop() { players.values().forEach(Player::disconnect); }
 
 	/**
 	 * Assigns the players their opposite colors.
 	 */
-	public void swapColors() {
+	public synchronized void swapColors() {
 		players.values().forEach(Player::cancelMove);
 		Player	white	= players.get(Color.WHITE);
 		Player	black	= players.get(Color.BLACK);

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

@@ -37,12 +37,13 @@ public class NaturalPlayer extends Player implements MouseListener {
 	/**
 	 * Creates an instance of {@link NaturalPlayer}.
 	 *
+	 * @param game             the game in which this player will be used
 	 * @param color            the piece color this player will control
 	 * @param overlayComponent the overlay component that will be used to display
 	 *                         possible moves to the user
 	 */
-	public NaturalPlayer(Color color, OverlayComponent overlayComponent) {
-		super(color);
+	public NaturalPlayer(Game game, Color color, OverlayComponent overlayComponent) {
+		super(game, color);
 		this.overlayComponent	= overlayComponent;
 		name					= "Player";
 		moveRequested			= false;

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

@@ -17,17 +17,23 @@ import dev.kske.chess.board.Piece.Color;
  */
 public abstract class Player {
 
-	protected Game		game;
-	protected Board		board;
-	protected Color		color;
+	protected final Game	game;
+	protected final Board	board;
+
 	protected String	name;
+	protected Color		color;
 
 	/**
 	 * Initializes the color of this player.
 	 *
+	 * @param game  the game in which this player will be used
 	 * @param color the piece color that this player will control
 	 */
-	public Player(Color color) { this.color = color; }
+	public Player(Game game, Color color) {
+		this.game	= game;
+		board		= game.getBoard();
+		this.color	= color;
+	}
 
 	/**
 	 * Initiates a move generation and reports the result to the game by calling
@@ -50,17 +56,6 @@ public abstract class Player {
 	 */
 	public Game getGame() { return game; }
 
-	/**
-	 * Sets the game in which this player is used. The board of that game will be
-	 * assigned as well.
-	 *
-	 * @param game the game to set
-	 */
-	public void setGame(Game game) {
-		this.game	= game;
-		board		= game.getBoard();
-	}
-
 	/**
 	 * @return the board on which this player is used
 	 */

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

@@ -27,11 +27,12 @@ public class UCIPlayer extends Player implements UCIListener {
 	/**
 	 * Creates an instance of {@link UCIPlayer}.
 	 *
+	 * @param game       the game in which this player will be used
 	 * @param color      the piece color that this player will control
 	 * @param enginePath the path to the engine executable
 	 */
-	public UCIPlayer(Color color, String enginePath) {
-		super(color);
+	public UCIPlayer(Game game, Color color, String enginePath) {
+		super(game, color);
 		try {
 			handle = new UCIHandle(enginePath);
 			handle.registerListener(this);

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

@@ -9,6 +9,7 @@ import javax.swing.SwingUtilities;
 import dev.kske.chess.board.Board;
 import dev.kske.chess.board.Move;
 import dev.kske.chess.board.Piece.Color;
+import dev.kske.chess.game.Game;
 import dev.kske.chess.game.Player;
 
 /**
@@ -31,38 +32,34 @@ public class AIPlayer extends Player {
 	/**
 	 * Creates an instance of {@link AIPlayer}.
 	 *
+	 * @param game               the game in which this player will be used
 	 * @param color              the piece color this player will control
 	 * @param maxDepth           the maximum search depth
 	 * @param alphaBetaThreshold the board evaluation threshold that has to be
 	 *                           reached to continue searching the children of a
 	 *                           move
 	 */
-	public AIPlayer(Color color, int maxDepth, int alphaBetaThreshold) {
-		super(color);
+	public AIPlayer(Game game, Color color, int maxDepth, int alphaBetaThreshold) {
+		super(game, color);
 		name					= "AIPlayer";
 		availableProcessors		= Runtime.getRuntime().availableProcessors();
 		this.maxDepth			= maxDepth;
 		this.alphaBetaThreshold	= alphaBetaThreshold;
-		exitRequested			= false;
 	}
 
 	@Override
 	public void requestMove() {
 		exitRequested = false;
-		/*
-		 * Define some processing threads, split the available moves between them and
-		 * retrieve the result after their execution.
-		 */
+
+		// Define some processing threads, split the available moves between them and
+		// retrieve the result after their execution.
 		new Thread(() -> {
-			/*
-			 * Get a copy of the board and the available moves.
-			 */
+
+			// Get a copy of the board and the available moves.
 			Board		board	= new Board(this.board, false);
 			List<Move>	moves	= board.getMoves(color);
 
-			/*
-			 * Define move processors and split the available moves between them.
-			 */
+			// Define move processors and split the available moves between them.
 			int					numThreads	= Math.min(moves.size(), availableProcessors);
 			List<MoveProcessor>	processors	= new ArrayList<>(numThreads);
 			final int			step		= moves.size() / numThreads;
@@ -71,23 +68,21 @@ 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, false), moves.subList(beginIndex, endIndex), color,
-						maxDepth, alphaBetaThreshold));
+				processors.add(new MoveProcessor(new Board(board, false), moves.subList(beginIndex, endIndex), color, maxDepth, alphaBetaThreshold));
 				beginIndex = endIndex;
 			}
 
-			/*
-			 * Execute processors, get the best result and pass it back to the Game class
-			 */
+			// Execute processors, get the best result and pass it back to the Game class
 			executor = Executors.newFixedThreadPool(numThreads);
 			List<ProcessingResult> results = new ArrayList<>(numThreads);
 			try {
 				List<Future<ProcessingResult>> futures = executor.invokeAll(processors);
 				for (Future<ProcessingResult> f : futures)
 					results.add(f.get());
-				executor.shutdown();
 			} catch (InterruptedException | ExecutionException ex) {
 				ex.printStackTrace();
+			} finally {
+				executor.shutdown();
 			}
 			results.sort((r1, r2) -> Integer.compare(r2.score, r1.score));
 			if (!exitRequested) SwingUtilities.invokeLater(() -> game.onMove(this, results.get(0).move));

src/dev/kske/chess/io/TextureUtil.java

@@ -37,7 +37,7 @@ public class TextureUtil {
 	 * @return The fitting texture
 	 */
 	public static Image getPieceTexture(Piece piece) {
-		String key = piece.toString().toLowerCase() + "_" + piece.getColor().toString().toLowerCase();
+		String key = piece.getClass().getSimpleName().toLowerCase() + "_" + piece.getColor().toString().toLowerCase();
 		return scaledTextures.get(key);
 	}
 

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

@@ -1,7 +1,6 @@
 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;
@@ -29,47 +28,31 @@ import dev.kske.chess.pgn.PGNGame;
  */
 public class MainWindow extends JFrame {
 
-	private static final long serialVersionUID = -3100939302567978977L;
+	private JTabbedPane tabbedPane = new JTabbedPane();
 
-	private JTabbedPane tabbedPane;
+	private static final long serialVersionUID = -3100939302567978977L;
 
 	/**
 	 * Launch the application.
 	 *
 	 * @param args command line arguments are ignored
 	 */
-	public static void main(String[] args) {
-		EventQueue.invokeLater(() -> {
-			try {
-				new MainWindow();
-			} catch (Exception ex) {
-				ex.printStackTrace();
-			}
-		});
-	}
+	public static void main(String[] args) { SwingUtilities.invokeLater(() -> new MainWindow()); }
 
 	/**
 	 * Create the application.
 	 */
-	public MainWindow() {
+	private MainWindow() {
 		super("Chess by Kai S. K. Engelbart");
-		initialize();
-	}
 
-	/**
-	 * Initialize the contents of the frame.
-	 */
-	private void initialize() {
 		// Configure frame
 		setResizable(false);
 		setBounds(100, 100, 494, 565);
 		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 		setIconImage(Toolkit.getDefaultToolkit().getImage(getClass().getResource("/pieces/queen_white.png")));
 
-		// Add frame content
-		tabbedPane = new JTabbedPane();
+		// Add tabbed pane, menu bar and drop target
 		getContentPane().add(tabbedPane);
-
 		setJMenuBar(new MenuBar(this));
 		new DropTarget(this, new GameDropTarget(this));