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Question

我正在尝试用Java编写JFrames，每当我运行程序时，会出现一个空窗口。我添加了我的按钮，我的面板，但它完全是空白的。是否有任何关于JFrame的具体内容我应该知道可能导致这个错误？最终产品根本没有按钮。我已经检查过每个方法都已被调用。

作为澄清，我不是要求进行代码修改，因为我的代码太长而且我不知道如何简化它，也不知道这个问题是否足够，为了提供一个例子。 我发帖的原因是询问JFrame的性质以及在什么条件下这样的空白屏幕。我还查看了如何简化代码的帖子，它没有＆＃39 ; t似乎适用（纠正我，如果我错了）因为我的问题是缺乏道岔，所以逐位删除代码不会导致错误消失。

完整代码：

    public class MineSweeperVisual extends JFrame{

private JButton[] buttons;
private JPanel panel;
private String[][] grid;
private int height;
private int width;
private JButton flagButton;
private boolean flag;
private JLabel result;


public MineSweeperVisual(int height2, int width2, int bombs) {
    height = height2;
    width = width2;
    buttons = new JButton[height * width];
    flag = false;
    result = new JLabel("Playing");

    grid = new String[height][width];
    for (int i = 0; i < bombs; i++) {
        int x = (int) (Math.random()*width);
        int y = (int) (Math.random()*height);
        grid[y][x] = "BH";
    }
    grid = resetGrid(grid, height, width);

    loadButtons();
    createFlagButton();
    createPanel();

    setSize(20 * width, 20 * height);
    setLocationRelativeTo(null);
}

public void createPanel() {
    panel = new JPanel();
    for(JButton i: buttons)
        panel.add(i);
    panel.add(flagButton);
    panel.add(result);
    setBackground(Color.BLACK);
}

public void loadButtons() {
    for (int i = 0; i < height * width; i ++) {
        buttons[i] = createGameButton(i);
    }
}

public JButton createGameButton(int i) {
    JButton button = new JButton(grid[i / width][i % height].substring(0,1));
    button.setPreferredSize(new Dimension(20,20));
    int y = i / 10;
    int x = i % 10;

    class RevealListener implements ActionListener {
    public void actionPerformed(ActionEvent event) {
        if (flag) {
            grid[y][x] = grid[y][x].substring(0,1) + "F";
        } else {
            grid[y][x] = grid[y][x].substring(0,1) + "R";
            if (grid[y][x].substring(0,1).equals("B")) {
                result.setText("You lost due to explosion");
            }
            grid = zeroChange(grid, height, width, x, y);
                for (int y1 = 0; y1 < height; y1 ++) {
                    for (int x1 = 0; x1 < width; x1++) {
                        if (grid[y1][x1].substring(0,2).equals("0R")) {
                            grid = adjacentToZeroChange(grid, height, width, x1, y1);
                        }
                    }
                }
            }
        }
    }

    ActionListener listener = new RevealListener();
    button.addActionListener(listener);
    return button;
}

private void createFlagButton () {
    flagButton = new JButton("Flag Mode");

    class FlagListener implements ActionListener {
        public void actionPerformed(ActionEvent event) {
            if (!flag)
                flag = true;
            else
                flag = false;
        }
    }
    ActionListener listener = new FlagListener();
    flagButton.addActionListener(listener);
}

public static void main(String[] args) throws IOException {
    Scanner in = new Scanner(System.in);

    System.out.print("Enter the first dimension of the grid: ");
    int width = in.nextInt();

    System.out.print("Enter the second dimension of the grid: ");
    int height = in.nextInt();

    System.out.print("Enter the amount of bombs on the grid: ");
    int bombs = in.nextInt();

    JFrame frame = new MineSweeperVisual(height, width, bombs);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setVisible(true);
}public static String[][] adjacentToZeroChange(String[][] grid1, int height, int width, int x, int y) {
    String[][] grid = grid1;
    if (grid[y][x].substring(0,1).equals("0")) {
        if (y - 1 >= 0 && x - 1 >= 0 && grid[y - 1][x - 1] != null && !grid[y - 1][x - 1].substring(1,2).equals("F"))   {
            grid[y - 1][x - 1] = "" + grid[y - 1][x - 1].substring(0,1) + "R";
        }
        if (y - 1 >= 0 && grid[y - 1][x] != null && !grid[y - 1][x].substring(1,2).equals("F")) {
            grid[y - 1][x]  = "" + grid[y - 1][x].substring(0,1) + "R";
        }
        if (y - 1 >= 0 && x + 1 < width && grid[y - 1][x + 1] != null && !grid[y - 1][x + 1].substring(1,2).equals("F")) {
            grid[y - 1][x + 1] =  "" + grid[y - 1][x + 1].substring(0,1) + "R";
        }
        if (x - 1 >= 0 && grid[y][x - 1] != null && !grid[y][x - 1].substring(1,2).equals("F")) {
            grid[y][x - 1] =  "" + grid[y][x - 1].substring(0,1) + "R";
        }
        if (x + 1 < width && grid[y][x + 1] != null && !grid[y][x + 1].substring(1,2).equals("F"))  {
            grid[y][x + 1] = "" + grid[y][x + 1].substring(0,1) + "R";
        }
        if (y + 1 < height && x - 1 >= 0 && grid[y + 1][x - 1] != null && !grid[y + 1][x - 1].substring(1,2).equals("F"))   {
            grid[y + 1][x - 1]  =  "" + grid[y + 1][x - 1].substring(0,1) + "R";
        }
        if (y + 1 < height && grid[y + 1][x] != null && !grid[y + 1][x].substring(1,2).equals("F")) {
            grid[y + 1][x] = "" + grid[y + 1][x].substring(0,1) + "R";
        }
        if (y + 1 < height && x + 1 < width && grid[y + 1][x + 1] != null && !grid[y + 1][x + 1].substring(1,2).equals("F"))    {
            grid[y + 1][x + 1] = "" + grid[y + 1][x + 1].substring(0,1) + "R";
        }
    }
    return grid;
}
public static String[][] zeroChange(String[][] grid1, int height, int width, int x, int y) {
    String[][] grid = grid1;
    if (y - 1 >= 0 && x - 1 >= 0 && grid[y - 1][x - 1] != null && grid[y - 1][x - 1].substring(0,2).equals("0H"))   {
        grid[y - 1][x - 1] = "0R";
        grid = zeroChange(grid, height, width, y -1, x -1);
    }
    if (y - 1 >= 0 && grid[y - 1][x] != null && grid[y - 1][x].substring(0,2).equals("0H")) {
        grid[y - 1][x]  = "0R";
        grid = zeroChange(grid, height, width, y -1, x);
    }
    if (y - 1 >= 0 && x + 1 < width && grid[y - 1][x + 1] != null && grid[y - 1][x + 1].substring(0,2).equals("0H")) {
        grid[y - 1][x + 1] = "0R";
        grid = zeroChange(grid, height, width, y -1, x +1);
    }
    if (x - 1 >= 0 && grid[y][x - 1] != null && grid[y][x - 1].substring(0,2).equals("0H")) {
        grid[y][x - 1] = "0R";
        grid = zeroChange(grid, height, width, y, x -1);
    }
    if (x + 1 < width && grid[y][x + 1] != null && grid[y][x + 1].substring(0,2).equals("0H"))  {
        grid[y][x + 1] = "0R";
        grid = zeroChange(grid, height, width, y, x +1);
    }
    if (y + 1 < height && x - 1 >= 0 && grid[y + 1][x - 1] != null && grid[y + 1][x - 1].substring(0,2).equals("0H"))   {
        grid[y + 1][x - 1]  = "0R";
        grid = zeroChange(grid, height, width, y +1, x -1);
    }
    if (y + 1 < height && grid[y + 1][x] != null && grid[y + 1][x].substring(0,2).equals("0H")) {
        grid[y + 1][x] = "0R";
        grid = zeroChange(grid, height, width, y +1, x);
    }
    if (y + 1 < height && x + 1 < width && grid[y + 1][x + 1] != null && grid[y + 1][x + 1].substring(0,2).equals("0H"))    {
        grid[y + 1][x + 1] = "0R";
        grid = zeroChange(grid, height, width, y +1, x +1);
    }

    if (grid[y][x].substring(0,1).equals("0")) {
        grid = adjacentToZeroChange(grid, height, width, x, y);
    }

    return grid;
}
public static int spotCheck(String[][] grid, int x, int y, int width, int height) {
    int bAmount = 0;
    if (y - 1 >= 0 && x - 1 >= 0 && grid[y - 1][x - 1] != null && grid[y - 1][x - 1].substring(0,1).equals("B"))    {
        bAmount++;
    }
    if (y - 1 >= 0 && grid[y - 1][x] != null && grid[y - 1][x].substring(0,1).equals("B")) {
        bAmount++;
    }
    if (y - 1 >= 0 && x + 1 < width && grid[y - 1][x + 1] != null && grid[y - 1][x + 1].substring(0,1).equals("B")) {
        bAmount++;
    }
    if (x - 1 >= 0 && grid[y][x - 1] != null && grid[y][x - 1].substring(0,1).equals("B"))  {
        bAmount++;
    }
    if (x + 1 < width && grid[y][x + 1] != null && grid[y][x + 1].substring(0,1).equals("B"))   {
        bAmount++;
    }
    if (y + 1 < height && x - 1 >= 0 && grid[y + 1][x - 1] != null && grid[y + 1][x - 1].substring(0,1).equals("B"))    {
        bAmount++;
    }
    if (y + 1 < height && grid[y + 1][x] != null && grid[y + 1][x].substring(0,1).equals("B"))  {
        bAmount++;
    }
    if (y + 1 < height && x + 1 < width && grid[y + 1][x + 1] != null && grid[y + 1][x + 1].substring(0,1).equals("B")) {
        bAmount++;
    }
    return bAmount;
}
public static String[][] resetGrid(String[][] grid, int height, int width) {
    String[][] change = grid;
    for (int y = 0; y < height; y ++) {
        for (int x = 0; x < width; x ++) {
            if (change[y][x] != null && change[y][x].substring(0,1).equals("B"))
                continue;
            else {
                change[y][x] = "" + spotCheck(change, x, y, width, height) + "H";
            }
        }
    }
    return change;
}

}

Answer 1

关于JFrame的性质以及在什么条件下它会像这样的空屏幕

您没有向窗口添加任何内容
在添加任何组件并且无法在revalidate（或其他子容器）上调用repaint和contentPane之前，您已将窗口显示为
您已移除/添加了组件，但未在受影响的容器上调用revalidate和repaint
您阻止了事件调度线程的一些长时间运行或阻止操作，导致无法绘制/更新UI
您已经进行了一定程度的自定义绘画并打破了进度中的绘画链

进行一系列猜测

根据其他代码进行更新...

根据现有资料......

public MineSweeperVisual(int height2, int width2, int bombs) {
    height = height2;
    width = width2;
    buttons = new JButton[height * width];
    flag = false;
    result = new JLabel("Playing");

    grid = new String[height][width];
    for (int i = 0; i < bombs; i++) {
        int x = (int) (Math.random()*width);
        int y = (int) (Math.random()*height);
        grid[y][x] = "BH";
    }
    grid = resetGrid(grid, height, width);

    loadButtons();
    createFlagButton();
    createPanel();

    setSize(20 * width, 20 * height);
    setLocationRelativeTo(null);
}

public void createPanel() {
    panel = new JPanel();
    for(JButton i: buttons)
        panel.add(i);
    panel.add(flagButton);
    panel.add(result);
    setBackground(Color.BLACK);
}

panel永远不会添加到框架

因此，在进行了一些修改以使代码运行之后，我将panel添加到contentPane的{{1}}，而不是JFrame， setSize（因为它没有在我的电脑上正确布局）

pack

这表明您可能需要仔细查看Laying Out Components Within a Container

Answer 2

您从未将面板添加到相框中。由于您已经扩展了JPanel，只需在框架可见之前设置所有内容，然后将面板添加到框架中。否则，您还创建了一个JFrame，这是必要的，因为您已经扩展了它，删除其中一个，然后执行相同的过程。你的代码应该在那之后工作。

在什么条件下，Java中的JFrame为空

2 个答案:

根据其他代码进行更新...