Added alpha-beta pruning threshold to the AI and a configuration dialog

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

@@ -25,14 +25,16 @@ public class AIPlayer extends Player {
 
 	private int	availableProcessors;
 	private int	maxDepth;
+	private int	alphaBetaThreshold;
 
 	private volatile boolean exitRequested;
 	private volatile ExecutorService	executor;
 
-	public AIPlayer(Board board, Color color, int maxDepth) {
+	public AIPlayer(Board board, Color color, int maxDepth, int alphaBetaThreshold) {
 		super(board, color);
 		availableProcessors	= Runtime.getRuntime().availableProcessors();
 		this.maxDepth		= maxDepth;
+		this.alphaBetaThreshold	= alphaBetaThreshold;
 		exitRequested		= false;
 	}
 
@@ -62,7 +64,8 @@ public class AIPlayer extends Player {
 				if (rem-- > 0) ++endIndex;
 				endIndex += step;
 				processors.add(
-						new MoveProcessor((Board) board.clone(), moves.subList(beginIndex, endIndex), color, maxDepth));
+						new MoveProcessor((Board) board.clone(), moves.subList(beginIndex, endIndex), color, maxDepth,
+								alphaBetaThreshold));
 				beginIndex = endIndex;
 			}
 

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

@@ -16,17 +16,19 @@ import dev.kske.chess.board.Piece.Color;
 public class MoveProcessor implements Callable<ProcessingResult> {
 
 	private final Board			board;
-	private final List<Move>	rootMoves;;
+	private final List<Move>	rootMoves;
 	private final Color			color;
 	private final int			maxDepth;
+	private final int			alphaBetaThreshold;
 
 	private Move bestMove;
 
-	public MoveProcessor(Board board, List<Move> rootMoves, Color color, int maxDepth) {
+	public MoveProcessor(Board board, List<Move> rootMoves, Color color, int maxDepth, int alphaBetaThreshold) {
 		this.board		= board;
 		this.rootMoves	= rootMoves;
 		this.color		= color;
 		this.maxDepth	= maxDepth;
+		this.alphaBetaThreshold	= alphaBetaThreshold;
 	}
 
 	@Override
@@ -43,7 +45,7 @@ public class MoveProcessor implements Callable<ProcessingResult> {
 			int		enemyValue		= board.evaluate(color.opposite());
 			int		valueChange		= teamValue - enemyValue;
 
-			if (depth < maxDepth && valueChange >= 0)
+			if (depth < maxDepth && valueChange >= alphaBetaThreshold)
 				valueChange -= miniMax(board, board.getMoves(color.opposite()), color.opposite(), depth + 1);
 
 			if (valueChange > bestValue) {

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

@@ -0,0 +1,82 @@
+package dev.kske.chess.ui;
+
+import java.awt.Dimension;
+
+import javax.swing.JButton;
+import javax.swing.JDialog;
+import javax.swing.JLabel;
+import javax.swing.JSpinner;
+import javax.swing.SpinnerNumberModel;
+
+/**
+ * Project: <strong>Chess</strong><br>
+ * File: <strong>AIConfigDialog.java</strong><br>
+ * Created: <strong>16.07.2019</strong><br>
+ * Author: <strong>Kai S. K. Engelbart</strong>
+ */
+public class AIConfigDialog extends JDialog {
+
+	private static final long serialVersionUID = -8047984368152479992L;
+
+	private int		maxDepth;
+	private int		alphaBetaThreshold;
+	private boolean	startGame	= false;
+
+	public AIConfigDialog() {
+		setSize(new Dimension(293, 212));
+		setModal(true);
+		setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
+		setTitle("AI Configuration");
+		getContentPane().setLayout(null);
+
+		JSpinner spAlphaBetaThreshold = new JSpinner();
+		spAlphaBetaThreshold.setBounds(170, 0, 95, 28);
+		getContentPane().add(spAlphaBetaThreshold);
+		spAlphaBetaThreshold.setModel(new SpinnerNumberModel(-10, -100, 100, 5));
+
+		JSpinner spMaxDepth = new JSpinner();
+		spMaxDepth.setBounds(170, 68, 95, 28);
+		getContentPane().add(spMaxDepth);
+		spMaxDepth.setModel(new SpinnerNumberModel(4, 1, 10, 1));
+
+		JLabel lblAlphabetaThreshold = new JLabel("Alpha-Beta Threshold:");
+		lblAlphabetaThreshold.setBounds(16, 68, 119, 28);
+		getContentPane().add(lblAlphabetaThreshold);
+
+		JButton btnOk = new JButton("OK");
+		btnOk.setBounds(16, 137, 84, 28);
+		getContentPane().add(btnOk);
+		btnOk.addActionListener((evt) -> {
+			maxDepth			= ((Integer) spMaxDepth.getValue()).intValue();
+			alphaBetaThreshold	= ((Integer) spAlphaBetaThreshold.getValue()).intValue();
+			startGame			= true;
+			dispose();
+		});
+		btnOk.setToolTipText("Start the game");
+
+		JButton btnCancel = new JButton("Cancel");
+		btnCancel.setBounds(170, 137, 95, 28);
+		getContentPane().add(btnCancel);
+		btnCancel.addActionListener((evt) -> dispose());
+		btnCancel.setToolTipText("Cancel the game start");
+
+		JLabel lblMaximalRecursionDepth = new JLabel("Maximal Recursion Depth:");
+		lblMaximalRecursionDepth.setBounds(16, 6, 141, 16);
+		getContentPane().add(lblMaximalRecursionDepth);
+
+		setLocationRelativeTo(null);
+	}
+
+	public int getMaxDepth() { return maxDepth; }
+
+	public void setMaxDepth(int maxDepth) { this.maxDepth = maxDepth; }
+
+	public int getAlphaBetaThreshold() { return alphaBetaThreshold; }
+
+	public void setAlphaBetaThreshold(int alphaBetaThreshold) { this.alphaBetaThreshold = alphaBetaThreshold; }
+
+	public boolean isStartGame() { return startGame; }
+
+	public void setStartGame(boolean startGame) { this.startGame = startGame; }
+
+}

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

@@ -54,14 +54,19 @@ public class MenuBar extends JMenuBar {
 		});
 
 		aiMenuItem.addActionListener((evt) -> {
+			AIConfigDialog dialog = new AIConfigDialog();
+			dialog.setVisible(true);
+			if (dialog.isStartGame()) {
 				players.put(Color.WHITE, new NaturalPlayer(board, Color.WHITE, overlayComponent));
-			players.put(Color.BLACK, new AIPlayer(board, Color.BLACK, 5));
+				players.put(Color.BLACK,
+						new AIPlayer(board, Color.BLACK, dialog.getMaxDepth(), dialog.getAlphaBetaThreshold()));
 				startGame();
+			}
 		});
 
 		aiVsAiMenuItem.addActionListener((evt) -> {
-			players.put(Color.WHITE, new AIPlayer(board, Color.WHITE, 5));
+			players.put(Color.WHITE, new AIPlayer(board, Color.WHITE, 4, -10));
-			players.put(Color.BLACK, new AIPlayer(board, Color.BLACK, 4));
+			players.put(Color.BLACK, new AIPlayer(board, Color.BLACK, 3, 0));
 			startGame();
 		});