为什么我不能在JPanel内的InternalFrame中放置托盘中的任何内容？

Question

我试图进行太阳系模拟 我在jPanel中绘制了行星和太阳，在jPanel中我添加了内部框架来添加来自pallete的东西，但是当它运行时，它只有太阳，按钮，标签等行星，它不存在

这是我在主类

中的代码

import java.awt.Dimension;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;

/**
 *
 * 
 */
public class UAS_PBOL_2014130005 {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // TODO code application logic here
        SwingUtilities.invokeLater(new Runnable() { //berguna untuk mendaftarkan sebuat objek Runnale kepada thread Event Dispatch, utk nantinya dikerjakan oleh thread tersebut

            public void run() {
                createAndShowGUI(); //tugas" yang dikerjakan adalah uang ada pada method run(), pada kasus ini adalah memanggil methid createAndSHowGUI()
            }
        });
    }

    private static void createAndShowGUI() {
        JFrame f = new JFrame("Solar System Simulation"); //membuat objek JFrame dengan judul window ("Swing..");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // Secara default, pas tombol "X" ditekan, program tidak dihentikan. Kode ini membuat program berhenti ketika tombol "X" ditekan

        f.add(new SolarSystem());
        f.setSize(700, 600);
        f.pack();
        f.setVisible(true);
    }
}

来自SolarSystem类

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Shape;
import java.awt.geom.AffineTransform;
import java.awt.geom.Ellipse2D;
import java.util.ArrayList;
import java.util.Random;
import javax.swing.JPanel;
import javax.swing.JSlider;

import uas_pbol_2014130005.Planet;
import uas_pbol_2014130005.TimePanel;

public class SolarSystem extends JPanel {

    public SolarSystem() {
        super();
        initComponents();
        init();
    }
    static final int WIDTH = 700;
    static final int HEIGHT = 600;
    ArrayList<Planet> planets = new ArrayList<>();
    float sun = 50;
    //final JSlider daySlider = new JSlider(0, SolarSystemModel.DAYS_PER_EARTH_REVOLUTION_AROUND_SUN);


    private void init() {
        Mercury();
        Venus();
        Earth();
        Mars();
        Jupiter();
        Saturn();
        Uranus();
        Neptune();
    }

    public void Mercury() {
        Planet mercury = new Planet(60, 0.1f, 5, Color.YELLOW);
        mercury.name("Mercury");
        addPlanet(mercury);
    }

    public void Venus() {
        Planet venus = new Planet(80, 0.07f, 7, Color.ORANGE);
        venus.name("Venus");
        addPlanet(venus);
    }

    public void Earth() {
        Planet earth = new Planet(95, 0.05f, 8, Color.BLUE);
        earth.satelit(1, new String[]{"Moon"});
        earth.name("Earth");
        addPlanet(earth);
    }

    public void Mars() {
        Planet mars = new Planet(110, 0.03f, 8, Color.CYAN);
        //mars.satelit(1, new String[] {"Moon"});
        mars.name("Mars");
        addPlanet(mars);
    }

    public void Jupiter() {
        Planet jupiter = new Planet(140, 0.025f, 17, Color.DARK_GRAY);
        //mars.satelit(1, new String[] {"Moon"});
        jupiter.name("Jupiter");
        addPlanet(jupiter);
    }

    public void Saturn() {
        Planet saturn = new Planet(170, 0.015f, 15, Color.GREEN);
        //mars.satelit(1, new String[] {"Moon"});
        saturn.name("Saturn");
        addPlanet(saturn);
    }

    public void Uranus() {
        Planet uranus = new Planet(205, 0.02f, 13, Color.MAGENTA);
        //mars.satelit(1, new String[] {"Moon"});
        uranus.name("Uranus");
        addPlanet(uranus);
    }

    public void Neptune() {
        Planet neptune = new Planet(230, 0.0145f, 10, Color.ORANGE);
        //mars.satelit(1, new String[] {"Moon"});
        neptune.name("Neptune");
        addPlanet(neptune);
    }

    public void addPlanet(Planet planet) {
        planets.add(planet);
    }

    private void draw1(Graphics2D g) {
        g.translate(WIDTH / 2, HEIGHT / 2);

        //draw sun
        Shape shape = new Ellipse2D.Float(-sun, -sun, sun * 2, sun * 2);
        g.setColor(Color.red);
        g.fill(shape);
        g.setColor(Color.YELLOW);
        g.drawString("Sun", 0, 0);

        //draw planets
        for (Planet planet : planets) {
            planet.rotate();
            planet.draw(g);
        }
        g.translate(WIDTH, HEIGHT);
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2d = (Graphics2D) g;
        g2d.setColor(Color.BLACK);
        g2d.fillRect(0, 0, WIDTH, HEIGHT);

        draw1(g2d);


        try {
            Thread.sleep(100);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        repaint();
    }

任何想法？ 先谢谢