java - JApplet setBackground 不工作

Question

我想知道为什么 setBackground() 方法实际上没有使背景变黑。我感觉这与实现 JApplet 的类有关，而不是 Applet，但我无法弄清楚具体细节。这真的很困扰我。如有任何帮助，我们将不胜感激!

import javax.swing.*;
import java.awt.*;

public class Rocket extends JApplet
{
    private final int APPLET_WIDTH = 200;
    private final int APPLET_HEIGHT = 200;

    private int[] xRocket = {100, 120, 120, 130, 130, 70, 70, 80, 80};
    private int[] yRocket = {15, 40, 115, 125, 150, 150, 125, 115, 40};

    private int[] xWindow = {95, 105, 110, 90};
    private int[] yWindow = {45, 45, 70, 70};

    private int[] xFlame = {70, 70, 75, 80, 90, 100, 110, 115, 120, 130, 130};
    private int[] yFlame = {155, 170, 165, 190, 170, 175, 160, 185, 160, 175, 155};

    public void init ()
    {
        setBackground (Color.black);
        setSize (APPLET_WIDTH, APPLET_HEIGHT);
    }

    public void paint (Graphics page)
    {
        page.setColor (Color.cyan);
        page.fillPolygon (xRocket, yRocket, xRocket.length);

        page.setColor (Color.gray);
        page.fillPolygon (xWindow, yWindow, xWindow.length);

        page.setColor (Color.red);
        page.drawPolyline (xFlame, yFlame, xFlame.length);
    }
} 

Answer 1

在 ContentPane 上设置颜色，而不是在父小程序组件上设置颜色

getContentPane().setBackground(Color.BLACK);

<小时/>

旁白:

对于 Swing 中的自定义绘制，重写 paintComponent 而不是 paint。 JApplet 不是 JComponent 的子类，因此需要基于此的新组件来执行此操作。确保调用 super.paintComponent(g)。