Graphics are not displayed in jlayeredpane (Java Swing)

I'm trying to build an image based on user input step by step What I'm trying to do is create a bunch of graphics and add them as layers, but I have some problems because they won't be displayed This is the code I'm using:

public class ClassA 
{
    protected final static int dimesionsY = 1000;
    private static int dimesionsX;
    private static JFrame window;
    private static JLayeredPane layeredPane;

    public void init()
    {
        window = new JFrame("Foo");
        dimesionsX = // some user input
        window.setPreferredSize(new Dimension(dimesionsX,dimesionsY));
        window.setLayout(new BorderLayout());

            layeredPane = new JLayeredPane();
        layeredPane.setBounds(0,dimesionsX,dimesionsY);
        window.add(layeredPane,BorderLayout.CENTER);

            ClassB myGraphic = new ClassB();    
        myGraphic.drawGraphic();

        layeredPane.add(myGrpahic,new Integer(0),0);

        window.pack();
        window.setVisible(true);
    }
}



public class ClassB extends JPanel
{
    public void drawGraphic()
    {
        repaint();
    }

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

        g.setColor(Color.BLACK);
        g.fillRect(10,10,100,100);
    }
}

But my figure doesn't seem to appear. I don't understand why I also tried to add it to JPanel and JPanel to jlayeredpane, but it didn't work

Could someone please help me?

Solution

Adding a component to a jlayeredpane is like adding it to an empty layout using a container: you must fully specify the size and location of the component

For example,

import java.awt.*;

import javax.swing.*;

public class ClassA {
   protected final static int dimesionsY = 800;
   protected final static int dimesionsX = 1000; //!!
   private static JFrame window;
   private static JLayeredPane layeredPane;

   public void init() {
      window = new JFrame("Foo");
      // !! dimesionsX = // some user input

      //!! window.setPreferredSize(new Dimension(dimesionsX,dimesionsY));
      window.setLayout(new BorderLayout());

      layeredPane = new JLayeredPane();
      //!! layeredPane.setBounds(0,dimesionsY);
      layeredPane.setPreferredSize(new Dimension(dimesionsX,dimesionsY));
      window.add(layeredPane,BorderLayout.CENTER);

      ClassB myGraphic = new ClassB();
      myGraphic.drawGraphic();

      myGraphic.setSize(layeredPane.getPreferredSize());
      myGraphic.setLocation(0,0);
      //!! layeredPane.add(myGraphic,0);
      layeredPane.add(myGraphic,JLayeredPane.DEFAULT_LAYER);

      window.pack();
      window.setVisible(true);
   }

   public static void main(String[] args) {
      new ClassA().init();
   }
}

class ClassB extends JPanel {
   public void drawGraphic() {
      repaint();
   }

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

      g.setColor(Color.BLACK);
      g.fillRect(10,100);
   }
}