Tendo problemas com um simples bloco de pintura em java. Problemas ao obter meu botão Limpar para redesenhar. A matriz está limpando, mas não repintando. Alguém pode identificar o meu problema ou existe alguma maneira diferente de gerar um botão de limpeza para este códig

public class DrawingPanel extends JPanel {
  private double x1=0;
  private double x2=0;
  private double y1=0;
  private double y2=0;

  private ArrayList<Shape> myArr = new ArrayList<Shape>();
  //private ArrayList<Shape> clearMyArr = new ArrayList<Shape>();
  ButtonPanel buttonPress;

   public void paintComponent(Graphics g) 
  {
     for (Shape i : myArr)
     {
        Graphics2D g2d = (Graphics2D)g;
        g2d.draw(i);
     }   
         /*for (Shape i : clearMyArr)
     {
        Graphics2D g2d = (Graphics2D)g;
        g2d.draw(i);
     }   */

  }         
    //inner class

   class Listener1 extends MouseAdapter
  {
      public void mousePressed(MouseEvent e)
     {
        x1=e.getX();
        y1=e.getY();
        System.out.println("Mouse Pressed");
     }

      public void mouseReleased(MouseEvent e)
     {
        x2=e.getX();
        y2=e.getY();
        Shape shape = null;
        if (buttonPress.buttonType.equals("Rectangle"))
        {
        // Rectangles cannot have a zero width or height
           if (x1 != x2 || y1 != y2)
           {
              double width = Math.abs(x1 -x2);
              double height = Math.abs(y1-y2);
              shape = new Rectangle2D.Double(Math.min(x1,x2),Math.min(y1,y2), width, height);
           }
        } 
        if (buttonPress.buttonType.equals("Eclipse"))
        {
           double width = Math.abs(x1 -x2);
           double height = Math.abs(y1-y2);
           shape = new Ellipse2D.Double(Math.min(x1,x2),Math.min(y1,y2), width, height);;
       } 
        if (buttonPress.buttonType.equals("Lines"))
        {
           shape = new Line2D.Double(x1, y1, x2, y2);

        } 
            if (buttonPress.buttonType.equals("Clear"))
        {
                for( int i = 0;i <= myArr.size(); i++ )
                {
                System.out.println("ArrayList Size :"+myArr.size());

                myArr.clear(); // clear all elements from arraylist 
                //clearMyArr.addAll(myArr);
                System.out.println("ArrayList Size :"+myArr.size()); 

                //myArr.removeAll();
                revalidate();
                repaint();
                }


        } 

        if (shape != null)
        {
           myArr.add(shape);

        }
        repaint();
     }


  }
//end of inner class

   public DrawingPanel(ButtonPanel reference)
  {
     buttonPress = reference;
     setBorder(BorderFactory.createLineBorder(Color.black,4));
     addMouseListener(new Listener1());      
  }

}