小编use*_*626的帖子

所以我是gui的新手,我想制作一个简单的程序来打印一个圆圈来代表太阳,然后在它附近我想打印另一个圆来代表一个星球.我的问题是当我添加方法paintPlanet时,gui窗口中返回的所有内容现在都是空白屏幕.即使我将paintPlanet评论出来,太阳的圆也不会打印出来,我留下一个空白的窗口.有人可以帮我弄清楚我哪里出错了如何修复它,这样两个圆圈都会打印出来？我是GUI新手,所以对我来说很容易:)

import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JPanel;


public class PlanetsLogic extends JPanel
{   
private static final long serialVersionUID = 1L;

public void paintSun(Graphics g)
{
    super.paintComponent(g);

    //create circle and fill it as yellow to represent the sun
    g.setColor(Color.YELLOW);
    g.drawOval(100, 75, 75, 75);
    g.fillOval(100, 75, 75, 75);
} //end paintSun


public void paintPlanet(Graphics g)
{
    super.paintComponent(g);
    //create circle and fill it as yellow to represent the orbiting planet
    g.setColor(Color.BLUE);
    g.drawOval(75, 75, 75, 75);
    g.fillOval(75, 75, 75, 75);


}//end paintPlanet

}//end class …