Java Buffer Strategy: compiler doesn't like it

Question

I am attempting to use double buffering with a canvas, something I've never done before. I took advantage of the tutorials online, and set up the following code to instantiate a canvas and set up the buffering for it. I coded the complete process including the rendering graphiocs (not shown here), and the compiler accepts it.

 volCanvas = new VolCanvas();
 volCanvas.setBackground(Color.black);
 volCanvas.setBounds(10, 380, 1180, 125);
 add(volCanvas);
 volCanvas.createBufferStrategy(2);            (Program blows up here)
 offScreen = volCanvas.getBufferStrategy();
 ofsg = (Graphics2D) offScreen.getDrawGraphics();

But the program blows up at the flagged line in the code below. The runtime throws an illegal state exception, with the explanation "Component must have a valid peer".

So far as I can tell, the source code is essentially as I've seen it in several examples, so I haven't a clue what is going on here. Any help would be greatly appreciated.

Thanks,

John Doner

Answer 1

Component must have a valid peer".

It basically means your GUI is not visible or you haven't added your component to a visible GUI.

Your other questions on the forum deal with Swing applications. You should not use an AWT component (Canvas) in a Swing application. Do custom painting on a JComponent or JPanel. Swing is double buffered by default.