[java]mon rond bondit pas

import java.awt.Dimension;
import javax.swing.JFrame;
public class Fenetre extends JFrame
{
  private Panneau pan=new Panneau();
 
  public Fenetre()
  {
    this.setTitle("Animation");
    this.setSize(300,300);
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    this.setLocationRelativeTo(null);
    this.setContentPane(pan);
    this.setVisible(true);
    go();
       }
       private void go()
            {
             int x=pan.getPosX(),y=pan.getPosY();
             boolean backX=false;
             boolean backY=false;
             while(true)
             {
              if(x<1)backX=false;
              if(x>pan.getWidth()-50)backX=true;
              if(y<1)backY=false;
              if(y>pan.getHeight()-50)backY=true;
              if(!backX)
               pan.setPosX(++x);
              else
               pan.setPosX(--x);
              if(!backY)
               pan.setPosX(++y);
              else
               pan.setPosX(--y);
               pan.repaint();
 
             try
             {
              Thread.sleep(3);
             }
             catch(InterruptedException e)
             {
              e.printStackTrace();
             }
         }
        }    
        public static void main(String[]args)
         {   
                 Fenetre pan=new Fenetre();    
         }
     } 
 
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Panneau extends JPanel
{
 private int posX=-50;
 private int posY=-50;
 
 public void paintComponent(Graphics g)
     { 
  g.setColor(Color.white);
  g.fillRect(0,0,this.getWidth(),this.getHeight());
  g.setColor(Color.red);//on redéfinit une couleur pour notre rond
  g.fillOval(posX,posY,50,50);
     }
 public int getPosX()
 {
  return posX;
 }
 public void setPosX(int posX)
 {
  this.posX=posX;
 }
 public int getPosY()
 {
  return posY;
 }
 public void setPosY(int posY)
 {
  this.posY=posY;
 }
}