title: Java graphics repaint problem
body: <p>Having trouble with a simple paint pad in java. Issues with getting my clear button to repaint. The array is clearing but not repainting. Can anyone spot my problem or is there any different way of generating a clear button for this code. </p>
  
  <pre><code>public class DrawingPanel extends JPanel {
    private double x1=0;
    private double x2=0;
    private double y1=0;
    private double y2=0;
  
    private ArrayList&lt;Shape&gt; myArr = new ArrayList&lt;Shape&gt;();
    //private ArrayList&lt;Shape&gt; clearMyArr = new ArrayList&lt;Shape&gt;();
    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 &lt;= 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());      
    }
  </code></pre>
  
  <p>}</p>