title: JLayeredPane error when the layer is an Integer
body: <p>I have a Canvas subclass object that I'm trying to add, along with some other Canvas subclasses, to a JLayeredPane.  In the documentation for JLayeredPane, the layer is given as an Integer, e.g.</p>
  
  <pre><code>layeredPane.add(child, new Integer(0));
  </code></pre>
  
  <p>However, when I use an Integer for the layer, I get some kind of runtime error.  (I can't really tell what this error is because my IDE keeps complaining about the lack source for the Swing libraries.)  Oddly, when I use the following form:</p>
  
  <pre><code>layeredPane.add(child, 0);
  </code></pre>
  
  <p>the line actually executes error-free.  I'm very new to Java and still haven't figured out how autoboxing works other than to form the opinion that it doesn't work very well.  I'm not sure if the bare 0 would be autoboxed in this case.</p>
  
  <p>I wish I could add more detail about this error, but I'm not even seeing an exception.  I will work on trimming my code down to a simple example, but I was hoping someone with experience with JLayeredPane has seen this before.</p>