java - Game Of Life Java MouseAdapter 并不总是有效

Question

有时会执行 mousePressed 事件，但有时则不会。这似乎还取决于您按下它的时间。我怎样才能让它始终工作？

我不确定代码的哪一部分有问题，所以这是整个类:

import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

import java.util.Random;

import javax.swing.JButton;
import javax.swing.JPanel;
import javax.swing.Timer;
public class Board extends JPanel implements ActionListener {
    Timer timer = new Timer(500, this);

    private boolean[][] board;
    private boolean isActive = false;
    private int height;
    private int width;
    private int multiplier = 20;

    private JButton btnRun;
    private JButton btnRand;
    private JButton btnClear;

    public Board() {
        this(new boolean[20][20]);
    }

    public Board(final boolean[][] board) {
        this.board = board;
        height = board.length;
        width = board[0].length;
        setBackground(Color.black);
        btnRun = new JButton("Run");
        add(btnRun);
        btnRun.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                isActive = !isActive;
                btnRun.setText(isActive ? "Pause" : "Run");
            }
        });
        btnRand = new JButton("Random");
        add(btnRand);
        btnRand.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                setBoard(randomBoard());
            }
        });
        btnClear = new JButton("Clear");
        add(btnClear);
        btnClear.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                setBoard(clearBoard());
            }
        });
        addMouseListener(new MouseAdapter() {
            @Override
            public void mousePressed(MouseEvent e) {
                getBoard()[e.getY() / multiplier][e.getX() / multiplier] = !getBoard()[e.getY() / multiplier][e.getX() / multiplier];
            }
        });
        timer.start();
    }

    public int getMultiplier() {
        return multiplier;
    }

    public boolean[][] getBoard() {
        return board;
    }

    public void setBoard(boolean[][] boardToSet) {
        for (int i = 0; i < height; i++) {
            for (int j = 0; j < width; j++) {
                board[i][j] = boardToSet[i][j];
            }
        }
    }

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        for (int i = 0; i < height; i++) {
            for (int j = 0; j < width; j++) {
                g.setColor(board[i][j] ? Color.green : Color.gray);
                g.fillRect(j * multiplier, i * multiplier, multiplier - 1, multiplier - 1);
            }
        }
        if (isActive) {
            timer.start();
        }
        else {
            timer.stop();
            repaint();
        }
    }

    public void actionPerformed(ActionEvent e) {
        board = nextGeneration();
        repaint();
    }

    public boolean[][] randomBoard() {
        Random rand = new Random();
        boolean[][] randBoard = new boolean[height][width];
        for (int i = 0; i < height; i++) {
            for (int j = 0; j < width; j++) {
                randBoard[i][j] = rand.nextBoolean();
            }
        }
        return randBoard;
    }

    public boolean[][] clearBoard() {
        boolean[][] emptyBoard = new boolean[height][width];
        for (int i = 0; i < height; i++) {
            for (int j = 0; j < width; j++) {
                emptyBoard[i][j] = false;
            }
        }
        return emptyBoard;
    }

    public int countSurrounding(int a, int b) {
        int count = 0;
        int[][] surrounding = {{a - 1, b - 1},
                               {a - 1, b    },
                               {a - 1, b + 1},
                               {a    , b - 1},
                               {a    , b + 1},
                               {a + 1, b - 1},
                               {a + 1, b    },
                               {a + 1, b + 1}};
        for (int[] i: surrounding) {
            try {
                if (board[i[0]][i[1]]) {
                    count++;
                }
            }
            catch (ArrayIndexOutOfBoundsException e) {}
        }
        return count;
    }

    public boolean[][] nextGeneration() {
        boolean[][] nextBoard = new boolean[height][width];
        for (int i = 0; i < height; i++) {
            for (int j = 0; j < width; j++) {
                nextBoard[i][j] = board[i][j];
            }
        }
        for (int i = 0; i < height; i++) {
            for (int j = 0; j < width; j++) {
                if (board[i][j] && !(countSurrounding(i, j) == 2 || countSurrounding(i, j) == 3)) {
                    nextBoard[i][j] = false;
                }
                else if (!board[i][j] && countSurrounding(i, j) == 3) {
                    nextBoard[i][j] = true;
                }
            }
        }
        return nextBoard;
    }   
}

Answer 1

在mousePressed()中添加一条System.out语句，您将看到它总是被调用:

    public void mousePressed(MouseEvent e) {
        System.out.println("mousePressed");
        getBoard()[e.getY() / multiplier][e.getX() / multiplier] = !getBoard()[e.getY() / multiplier][e.getX() / multiplier];
        repaint();
    }

就像您的 other very similar question 中的其他人建议的那样，问题源于您在绘制方法中使用计时器。

public void paintComponent(Graphics g) {
    super.paintComponent(g);
    for (int i = 0; i < height; i++) {
        for (int j = 0; j < width; j++) {
            g.setColor(board[i][j] ? Color.green : Color.gray);
            g.fillRect(j * multiplier, i * multiplier, multiplier - 1, multiplier - 1);
        }
    }
    //if (isActive) {  // take this stuff out...
    //    timer.start();
    //}
    //else {
    //    timer.stop();
    //    repaint();
    //}
}

paintComponent() 方法只能用于绘制组件。请勿使用它来启动/停止计时器、对 repaint() 进行额外调用或以其他方式调用任何其他类型的程序逻辑。重新思考您的设计，尤其是在 paintComponent() 中。