Java 没有调用 paintComponents

Question

我正在尝试在 JPanel 上画一些东西，但我似乎遇到了 paint 和 paintComponent 方法的问题。可能与双缓冲有关，但我不确定。 public void paintComponent(Graphics g) 方法由于某种原因没有被调用，知道为什么吗？

这是我的代码：

   @Override
public void paintComponents(Graphics g) {
    super.paintComponents(g); //To change body of generated methods, choose Tools | Templates.
    System.out.println("paintComponents!");

    snakeHead.DrawSphere(g);

    if(foodShoulBeRedrawn){
        foodShoulBeRedrawn = false;
        spawnFood();
    }

    if(shouldSpawnBodyPart){
        shouldSpawnBodyPart = false;
        snake.get(snake.size() - 1).DrawSphere(g);

    }

    //spawnSnake();
    paintCalled = true;

    repaint();
}

/*
@Override
public void paint(Graphics g) {
    super.paint(g);

    snakeHead.DrawSphere(g);

    if(foodShoulBeRedrawn){
        foodShoulBeRedrawn = false;
        spawnFood();
    }

    if(shouldSpawnBodyPart){
        shouldSpawnBodyPart = false;
        snake.get(snake.size() - 1).DrawSphere(g);

    }

    //spawnSnake();
    paintCalled = true;

    repaint();
}
*/

Answer 1

我认为 JFrame 不是 JComponent，因此永远不会调用 paintComponent 方法。您应该将所有绘制方法放在 JPanel 中并将其包含在您的 JFrame 中。

Answer 2

您正在覆盖 Container#paintComponents(), which was inherited by your JFrame. Instead of extending JFrame, you need to extend JPanel so you can override its paintComponent() and getPreferredSize(). Then you can add() the panel to a JFrame, like they show here and here。

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