您可能应该使用JComboBox允许用户在3个可用选项中进行选择。如果使用此JComboBox制作启动JFrame，则可以随后创建您的主游戏框架并将其值传递给JComboBox。

例如，您可以让JComboBox提供困难设置Easy，Medium和Hard的选项。在JButton上使用动作侦听器，从JComboBox获取选定的值，并将其转换为适合于minimax算法的int值。也就是说，通过1代表轻松，2代表中等，3代表艰苦。

接下来，更改您的ai类，以便将maxDepth放入构造函数中。然后，当实例化ai时，只需为其提供从前一帧传递来的值，就可以在正确的难度设置下创建所需的唯一ai。

编辑：

看来您设法完成了类似的工作，这真是太好了！为了对您有所帮助，我在下面提供了一个简短的示例，说明了如何进行此操作。请注意，我还对它进行了设置，以使您的SimpleAiPlayerHandler构造函数也采用一个int值来实例化maxDepth变量。您需要添加它。由于它使用的是我没有的类，因此我无法对其进行编译。但是，如果其他任何人需要做类似的事情，只需除去DifficultyListener中的所有内容，除了print语句和JComboBox遇到的困难的行，您就会发现它可以正常工作（并进行编译）。

import javax.swing.*;
import java.awt.event.*;

public class ChessSplash extends JFrame {
    private final JComboBox<Difficulty> difficultySetting;

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                ChessSplash gui = new ChessSplash();
                gui.setVisible(true);
            }
        });
    }

    public enum Difficulty {
        EASY(1, "Easy"), MEDIUM(2, "Medium"), HARD(3, "Hard");

        private final int intValue;
        private final String stringValue;

        private Difficulty(int intValue, String stringValue) {
            this.intValue = intValue;
            this.stringValue = stringValue;
        }

        @Override
        public String toString() {
            return stringValue;
        }
    };

    public ChessSplash() {
        super("Chess Game");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        difficultySetting = new JComboBox<>(Difficulty.values());
        JButton startButton = new JButton("Start Game");
        startButton.addActionListener(new DifficultyListener());
        JPanel mainPanel = new JPanel();
        add(mainPanel);
        mainPanel.add(difficultySetting);
        mainPanel.add(startButton);
        pack();
    }

    private class DifficultyListener implements ActionListener {
        @Override
        public void actionPerformed(ActionEvent e) {
            //Declare AI
            SimpleAiPlayerHandler ai;

            //Declare and Instantiate Chess Game
            ChessGame chessGame = new ChessGame();

            //Human Player is the Object chessGui
            ChessGui chessGui = new ChessGui(chessGame);
            //Assign Human Player to White
            chessGame.setPlayer(Piece.COLOR_WHITE, chessGui);

            //Get the selected difficulty setting
            Difficulty difficulty = (Difficulty)difficultySetting.getSelectedItem();

            //Instantiate Computer AI pass it the maxDepth for use in the constructor
            ai = new SimpleAiPlayerHandler(difficulty.intValue, chessGame);
            //Assign Computer Player to Black
            chessGame.setPlayer(Piece.COLOR_BLACK, ai);
            //Demonstrate the enum combobox works
            System.out.println(difficulty.intValue);

            //Dispose of the splash JFrame
            ChessSplash.this.dispose();

            //Start your game thread (I would probably do something to move this
            //onto the EDT if you're doing this is swing personally
            new Thread(chessGame).start();
        }
    }
}