title: Place image at random grid point on button click
body: <p>I'm using Java with Window builder
  I've created a 4x4 grid out of jlabels (each grid point is a different jlabel) on my jframe.
  I also have a button called btnPlace. 
  What I want to do is have an image appear at a random grid point on button click. The image file is called red.png which is a red circle. The image can appear at any grid point except the grid point number 1.<br>
  Sort of like this: <a href="http://i.stack.imgur.com/bBn6D.png" rel="nofollow">http://i.stack.imgur.com/bBn6D.png</a></p>
  
  <p>Here's my code:</p>
  
  <pre><code>public class grid {
  
  public static void main (String[] args) 
  { 
  
      JFrame grid =new JFrame();
      grid.setDefaultCloseOperation 
      (JFrame.EXIT_ON_CLOSE); 
  
      JPanel set = new JPanel();      
      set.setBounds(10, 11, 307, 287);
      grid.getContentPane().add(set);
      set.setLayout(new GridLayout(4, 4, 0, 0));
  
      JLabel a = new JLabel("");
      set.add(a);
  
      JLabel b = new JLabel("");      
      set.add(b);
  
      JLabel c = new JLabel("");      
      set.add(c);
  
      ^^ this repeats up to JLabel p. just to save time.
  
      JButton btnPlace = new JButton("Place");        
      grid.getContentPane().add(btnPlace);
      grid.setVisible(true); 
  }   }
  </code></pre>