Help me understand javax.swing/java.awt

Delzhand

I've done a fair bit of programming in other languages, but I've never done graphical work in straight up Java. Here's what I need help understanging:

public class sGraphics extends JFrame{
	private int w, h;
	public sGraphics(int x, int y){
		w = x;
		h = y;
		setVisible(true);
		setSize(w,h);
		setResizable(false);
		setUndecorated(true);
	}
	
	public void paint(Graphics g){
		g.translate(0,22);
		g.setColor(Color.black);
		g.fillRect(10,10,(w-20),(h-42));
	}
	

	public static void main(String[] args){
		sGraphics sg = new sGraphics(640, 480+22);
		sg.repaint();
	}
}

Okay - this displays a window with a black box (except for the border). But paint() is never called, instead, I see repaint(). I see that paint() should be called with a Graphics object, but I never specify any Graphics, and this class extends JFrame, not Graphics.

I'm trying to figure out double buffering. This seems like the beginnings, drawing a black backbuffer then flipping it to the screen, but how would I draw other stuff to the buffer first?

Bob Sapp

Are you familiar with callbacks and events?

Basically, the Java VM will call the paint method and will supply the Graphics object.

I haven't done graphics programming in Java, but have done tons of swing. So I can't help too much on the specifics of what you're trying to do outside of theoretical. (I've done it in Windows programming).

Edit: java.sun.com is your friend. Try this tutorial: http://java.sun.com/docs/books/tutorial/uiswing/14painting/index.html

Edit 2: You need to call update() on the JFrame to force a call to paint(). This is your bible: http://java.sun.com/j2se/1.5.0/docs/api/