JPanel setBackground(Color.BLACK) 什么都不做 [英] JPanel setBackground(Color.BLACK) does nothing

问题描述

我有以下自定义 JPanel，我已使用 Netbeans GUI 构建器将它添加到我的框架中，但背景不会改变！我可以看到圆圈，用 g.fillOval() 绘制.怎么了?

I have the folowing custom JPanel and I have aded it to my frame using Netbeans GUI builder but the background won't change! I can see the circle, drawing with g.fillOval(). What's wrong?

public class Board extends JPanel{

    private Player player;

    public Board(){
        setOpaque(false);
        setBackground(Color.BLACK);  
    }

    public void paintComponent(Graphics g){  
        super.paintComponent(g);
        g.setColor(Color.red);
        g.fillOval(player.getxCenter(), player.getyCenter(), player.getRadius(), player.getRadius());
    }

    public void updatePlayer(Player player){
        this.player=player;
    }
}

推荐答案

如果您的面板不透明"(透明)，您将看不到背景颜色.

If your panel is 'not opaque' (transparent) you wont see your background color.

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