“Buffers have not been created” … whilst creating buffers

Question

I have (what I thought was) a straightforward BufferStrategy for a JFrame. It is created like so:

    // Buffer
    container.createBufferStrategy(2);                


        

Answer 1

The frame needs to be displayable when you call createBufferStrategy. Also as camickr has pointed out you need to call it from the EDT.

One way to ensure this is to extend JFrame and override addNotify:

class MyFrame extends JFrame {
    public void addNotify() {
        super.addNotify();
        // Buffer
        createBufferStrategy(2);           
        strategy = getBufferStrategy();
    }
}

Answer 2

Swing components are double buffered by default, so there is no need to play around with a BufferStrategy.

However when you get random errors like that its usually because code is not executed on the EDT. Read the section from the Swing tutorial on Concurrency for more information.