Java 简单打印一个圆形GUI问题

所以我是gui新手，我想做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圈来代表行星。我的问题是，当我添加paintPlanet方法时，gui窗口中返回的所有内容现在都是空白屏幕。即使当我把paintPlanet注释掉时，太阳的圆圈也不会打印出来，我只剩下一个空白窗口。有人能帮我找出哪里出了问题，如何修复它，让两个圆圈都打印出来吗？我是GUI新手，所以请对我放松：）

主要内容：

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你的paintSun和paintPlanet方法永远不会被神奇地调用。相反，JPanel需要重写paintComponent方法，因为所有绘图都在那里完成。您甚至可以从paintComponent中调用paintSun和paintPlanet方法，但我建议只调用一次

super.paintComponent（g）

，并且只能从paintComponent方法重写自身中调用

e、 g

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你的paintSun和paintPlanet方法永远不会被神奇地调用。相反，JPanel需要重写paintComponent方法，因为所有绘图都在那里完成。您甚至可以从paintComponent中调用paintSun和paintPlanet方法，但我建议只调用一次

super.paintComponent（g）

，并且只能从paintComponent方法重写自身中调用

e、 g

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哇，我觉得自己太傻了，没听清楚。非常感谢。哇，我觉得自己太傻了，没听清楚。非常感谢。

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 PlanetsLogic

import javax.swing.JFrame;

public class OrbitingPlants_main 
{

public static void main(String[] args) 
{

    PlanetsLogic planet = new PlanetsLogic();
    JFrame frame = new JFrame();

    frame.setTitle("Orbiting Planets");
    frame.setSize(300, 300);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.add(planet); //add panel onto frame
    frame.setVisible(true); 
}

}

// use @Override to ask the compiler to check if this method is a true override
@Override
protected void paintComponent(Graphics g) {
    super.paintComponent(g); // HERE!
    paintSun(g);
    paintPlanet(g);
}

public void paintSun(Graphics g) {
    // super.paintComponent(g); // nope, not here!

    //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);  // NO don't call this here
    //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