触发ActionListener之后，如何更新Gridlayout

Question

我正在尝试建立一个包含一个播放器（红色正方形）的网格，该网格可以使用WASD键在网格周围移动。到目前为止，我的ActionListener正在注册按键，但是在呼叫网格（面板）上的RepAlt（）方法时，都没有任何更改。如何使董事会更新？

这是我的主要课程：

public class game {

    public static void main(String[] args) {
        JFrame GUI = new GUI();
        GUI.setVisible(true);
    }
}

这是我的自定义Jframe：

public class GUI extends JFrame implements KeyListener {
    
    //JPanel board = new board();
    public board board;

    public GUI() {
        super();
        board = new board();
        add(board);
        //setSize(800, 800);
        //setVisible(true);

        pack();
        addKeyListener(this);
        repaint();
    }

    @Override
    public void repaint() {
        super.repaint();
    }

    @Override
    public void keyPressed(KeyEvent e) {
        board.keyPressed(e);
        board.repaint();
    }

    @Override
    public void keyTyped(KeyEvent e) { }

    @Override
    public void keyReleased(KeyEvent e) { }
}

这是我的自定义JPanel类，它使用Jlabels构造网格：

public class board extends JPanel {

    public static final int GRID_SIZE = 20;

    int playerX = ThreadLocalRandom.current().nextInt(0, GRID_SIZE + 1);
    int playerY = ThreadLocalRandom.current().nextInt(0, GRID_SIZE + 1);

    public board() {

        //JPanel panel = new JPanel();

        int row = GRID_SIZE;
        int col = GRID_SIZE;

        setBounds(100, 100, 500, 500);
        setLayout(new GridLayout(col, row));

        JLabel[][] grid= new JLabel[col][row];
        for (int y = 0; y < col; y++){
            for (int x = 0; x < row; x++){
                grid[x][y] = new JLabel();
                grid[x][y].setBorder(BorderFactory.createLineBorder(Color.black));
                grid[x][y].setBackground(Color.white);
                grid[x][y].setOpaque(true);
                add(grid[x][y]);
            }
        }
        grid[playerX][playerY].setBackground(Color.red);
    }

    public void keyPressed(KeyEvent e) {
        int k = e.getKeyCode();

        switch (k) {
            case KeyEvent.VK_D:
                playerX++;
                break;
            case KeyEvent.VK_A:
                playerX--;
                break;
            case KeyEvent.VK_W:
                playerY--;
                break;
            case KeyEvent.VK_S:
                playerY++;
                break;
        }
    }

}

Answer 1

您必须更新回调中的背景。

public void keyPressed(KeyEvent e) {
    int k = e.getKeyCode();
    grid[playerX][playerY].setBackground(Color.WHITE); 
    switch (k) {
        case KeyEvent.VK_D:
            playerX++;
            break;
        case KeyEvent.VK_A:
            playerX--;
            break;
        case KeyEvent.VK_W:
            playerY--;
            break;
        case KeyEvent.VK_S:
            playerY++;
            break;
    }
    grid[playerX][playerY].setBackground(Color.red);
}