如何在方法中初始化 JFrame 后正确显示它

Question

这是一个很长的问题，请耐心等待。我正在制作一个 Game of Life 应用程序，它首先显示一个带有 JButton 网格的 JFrame。如果单击 JButton，它的背景会变黑，当再次激活时，它的背景会变回白色。我的代码：

public class Choose implements ActionListener {
public final static int DIMENSION = 50;
Color BLACK = new Color(0,0,0);
Color WHITE = new Color(255,255,255);
JFrame choose;
JButton[] choice;
JButton clear, fill, go;
JPanel baseChoose, baseFrame, buttonsAndText;
GridLayout base;

public Choose() {
    choose = new JFrame("Make your own game");
    choice = new JButton[DIMENSION*DIMENSION];

    baseChoose = new JPanel();
        baseChoose.setSize(500, 500);
    buttonsAndText = new JPanel();

    buttonsAndText.add(clear = new JButton("Clear"));
        clear.addActionListener(this);
    buttonsAndText.add(fill = new JButton("Fill"));
        fill.addActionListener(this);
    buttonsAndText.add(go = new JButton("Go"));
        go.addActionListener(this);

    base = new GridLayout(DIMENSION, DIMENSION);
        base.setHgap(-1);
        base.setVgap(-1);

    baseChoose.setLayout(base);
    choose.add(baseChoose);
    choose.add(buttonsAndText);

    JLabel text = new JLabel("Press 'Go' to start.");
    buttonsAndText.add(text);

    for (int i = 0; i < (DIMENSION*DIMENSION); i++) {
        baseChoose.add(choice[i] = new JButton());
        choice[i].setBackground(WHITE);
        choice[i].addActionListener(this);
    }

    choose.setSize(500, 800);
    choose.setVisible(true);
    choose.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    choose.setResizable(false);
}

public void actionPerformed(ActionEvent e) {
    JButton b = (JButton)e.getSource();

    for (int i = 0; i < (DIMENSION*DIMENSION); i++) {
        if (b == choice[i]) {
            if (b.getBackground() == BLACK) {
                choice[i].setBackground(WHITE);
            } else if (b.getBackground() == WHITE) {
                choice[i].setBackground(BLACK);
            }
        }
    }

    if (b == clear) {
        for (int i = 0; i < (DIMENSION*DIMENSION); i++) {
            choice[i].setBackground(WHITE);
        }
        choose.validate();
        choose.repaint();
    }

    if (b == fill) {
        for (int i = 0; i < (DIMENSION*DIMENSION); i++) {
            choice[i].setBackground(BLACK);
        }
        choose.validate();
        choose.repaint();
    }

    if (b == go) {
        int states[] = new int[DIMENSION*DIMENSION];
        for (int i = 0; i < DIMENSION*DIMENSION; i++) {
            System.out.println(choice[i].getBackground() == BLACK);
            if (choice[i].getBackground() == BLACK) {
                states[i] = 1;
            } else if (choice[i].getBackground() == WHITE) {
                states[i] = 0;
            }
        }
        choose.dispose();
        Gui own = new Gui(states);
    }
}
}

在我创建这个类的一个实例的 main 方法中，当您选择要激活的按钮后，您可以单击go 按钮来实际显示生命游戏。

public class Gui  {
public final static int DIMENSION = 50;
Color BLACK = new Color(0,0,0);
Color WHITE = new Color(255,255,255);
JFrame frame, ownFrame;
JPanel baseFrame;
GridLayout base;

public Gui(int[] states) {
    frame = new JFrame("Game of Life by Boris Verwoerd");

    baseFrame = new JPanel();
        baseFrame.setSize(500, 500);

    frame.add(baseFrame);

    base = new GridLayout(DIMENSION, DIMENSION);
        base.setHgap(-1);
        base.setVgap(-1);

    baseFrame.setLayout(base);

    JPanel[] box = new JPanel[DIMENSION*DIMENSION];

    for (int i = 0; i < (DIMENSION*DIMENSION); i++) {
        baseFrame.add(box[i] = new JPanel());
        box[i].setBorder(BorderFactory.createLineBorder(Color.black));
    }

    frame.setSize(500, 500);
    frame.setVisible(true);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setResizable(false);
    frame.validate();
    frame.repaint();

    gameLoop(box, frame, states);
}

private static void gameLoop(JPanel[] boxes, JFrame theFrame, int[] states) {
    int[] newstates = new int[DIMENSION*DIMENSION];
    for (int i = 0; i < 20; i++) {

        newstates = Maths.render(boxes, theFrame, states);
        states = newstates;
        theFrame.validate();
        theFrame.repaint();

        try {
            Thread.sleep(100);                 //1000 milliseconds is one second.
        } catch(InterruptedException ex) {
            Thread.currentThread().interrupt();
        }
    }
}

public static int getDim() {
    return DIMENSION;
}

}

按下 go 时，会启动一个新的 JFrame，但屏幕是全白的，只有在 gameLoop 结束后才会显示 JPanel 网格。

只有当我使用全零数组states 从主方法创建 Gui 实例时，它才能正确显示。 我已经尝试了很多方法来提出解决方案，但我不明白为什么它会导致这个白屏而不是网格。因此我的问题是：如何在从方法初始化时正确显示我的 Gui 实例，而不会出现白屏？

• 抱歉，帖子/代码太长了！

编辑：

这是我的数学课：

public class Maths {
static Color BLACK = new Color(0,0,0);
static Color WHITE = new Color(255,255,255);

public static int[] render(JPanel[] box, JFrame frame, int[] state) {
    int[] newstates = new int[Gui.getDim()*Gui.getDim()];
    for (int i = 0; i < (Gui.getDim()*Gui.getDim()); i++) newstates[i] = 0;

    for (int i = (Gui.getDim()+1); i < (Gui.getDim()*Gui.getDim() - (Gui.getDim()+1)); i++) {
        if (state[i] == 1) {
            int aliveNeighbours = 0;
            if (state[i-(Gui.getDim()+1)] == 1) aliveNeighbours++;
            if (state[i-Gui.getDim()] == 1) aliveNeighbours++;
            if (state[i-(Gui.getDim()-1)] == 1) aliveNeighbours++;
            if (state[i-1] == 1) aliveNeighbours++;
            if (state[i+1] == 1) aliveNeighbours++;
            if (state[i+(Gui.getDim()-1)] == 1) aliveNeighbours++;
            if (state[i+Gui.getDim()] == 1) aliveNeighbours++;
            if (state[i+(Gui.getDim()+1)] == 1) aliveNeighbours++;

            if (aliveNeighbours == 2 || aliveNeighbours == 3) {
                box[i].setBackground(BLACK);
                newstates[i] = 1;
            } else {
                box[i].setBackground(WHITE);
                newstates[i] = 0;
            }

        } else if (state[i] == 0) {
            int aliveNeighbours = 0;
            if (state[i-(Gui.getDim()+1)] == 1) aliveNeighbours++;
            if (state[i-Gui.getDim()] == 1) aliveNeighbours++;
            if (state[i-(Gui.getDim()-1)] == 1) aliveNeighbours++;
            if (state[i-1] == 1) aliveNeighbours++;
            if (state[i+1] == 1) aliveNeighbours++;
            if (state[i+(Gui.getDim()-1)] == 1) aliveNeighbours++;
            if (state[i+Gui.getDim()] == 1) aliveNeighbours++;
            if (state[i+(Gui.getDim()+1)] == 1) aliveNeighbours++;

            if (aliveNeighbours == 3) {
                box[i].setBackground(BLACK);
                newstates[i] = 1;
            } else {
                box[i].setBackground(WHITE);
                newstates[i] = 0;
            }
        }
    }
    return newstates;
}
}

Answer 1

您的问题是 Swing 线程问题的典型案例，这是由于您的长时间运行的代码还在 Swing 事件线程上调用 Thread.sleep(...)，这将使整个 GUI 进入睡眠状态，当然不是您的目标。

解决方案与任何类似问题相同（您应该在此处发布之前搜索并找到该问题）：如果您有长时间运行的代码，请使用 SwingWorker 进行后台线程，或者使用 Swing Timer 调用代码经常延迟。

您在此处使用哪一个取决于Maths.render 的速度有多慢。如果这计算得非常快，那么您只需要一个 Swing Timer 来间歇性地和延迟地进行此调用。如果此方法需要大量时间来执行，那么您将需要使用 SwingWorker 路线。

例如，计时器代码可能如下所示：

private void gameLoop() {
  int timerDelay = 100;
  new Timer(timerDelay, new ActionListener() {
     private final int maxIndex = 20;
     private int index = 0;

     @Override
     public void actionPerformed(ActionEvent e) {
        if (index < maxIndex) {
           states = Maths.render(box, frame, states);
           frame.validate();
           frame.repaint();
      } else {
           ((Timer) e.getSource()).stop();
        }
        index++;
     }
  }).start();
}

请注意，gameLoop 应该是一个非静态实例方法。我也不允许参数传递，而是将这些家伙作为类的字段：

private JPanel[] box;
private int[] states;

并确保设置这些字段：

public Gui(int[] states) {
  this.states = states;
  frame = new JFrame("Game of Life by Boris Verwoerd");

  baseFrame = new JPanel();
  baseFrame.setSize(500, 500);

  frame.add(baseFrame);

  base = new GridLayout(DIMENSION, DIMENSION);
  base.setHgap(-1);
  base.setVgap(-1);

  baseFrame.setLayout(base);

  box = new JPanel[DIMENSION * DIMENSION];

  for (int i = 0; i < (DIMENSION * DIMENSION); i++) {
     baseFrame.add(box[i] = new JPanel());
     box[i].setBorder(BorderFactory.createLineBorder(Color.black));
  }

  frame.setSize(500, 500);
  frame.setVisible(true);
  frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  frame.setResizable(false);
  frame.validate();
  frame.repaint();

  gameLoop();
}