Newb JPanel with rectangle and buttons

[radiodave]

I'm trying to create a UI with a rectangle to draw lines on, and some buttons. Trying different approaches, I seem to be able to do one or the other, but not both. I used setLayout(null) because I want the buttons in a specific place. When I run it, I see the rectangle OK, but I only see one button. If I leave out the setLayout(null), then I see both buttons, but they are superimposed on the box. I just want to put the buttons in a specific location, but it seems I need setLayout(null) in order to do that. What am I missing?

public class UI extends JPanel {
    private boolean bline;
    JButton ResetButton;
    JButton ZeroButton;

final int iButtonWidth  = 70;
    final int iButtonHeight = 70;
    
    
    final int iZeroButtonStartX = 100;
    final int iZeroButtonStartY = 200;
    final int iResetButtonStartX = 300;
    final int iResetButtonStartY = 200;

public void paint (Graphics g) {
        g.setColor(Color.black);
        g.fillRect(iDisplayStartX, iDisplayStartY, iDisplayWidth, iDisplayHeight);
        
        g.drawLine(20, 20, 40, 40);
            
    }

public UI ()
{
setLayout(null);
        ResetButton = new JButton("Reset");
        ResetButton.setBounds(iResetButtonStartX, iResetButtonStartY, iButtonWidth, iButtonHeight);
        ZeroButton = new JButton("0");
        ZeroButton.setBounds(iZeroButtonStartX, iZeroButtonStartY, iButtonWidth, iButtonHeight);
        add(ResetButton);
        add(ZeroButton);
        revalidate();

}

.
.
.

public static void main()
{
JFrame frame = new JFrame("TITLE");
        frame.add(new UI());
        frame.setSize(iWindowSizeX, iWindowSizeY);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
        frame.setResizable(false);
}

[SurfMan]

If you use a Null-layout, buttons need a bounds (width, height, x and y). If you set a layout of some sort, the LayoutManager will decide where the buttons go. By default, a JPanel uses a FlowLayout., so there is always a LayoutManager active for each new JPanel. Setting it to null will remove it.

First of all, you should override paintComponent(Graphics) and NOT paint(Graphics).

Second, public static void main requires String[] as parameter is you want this class to start.

[radiodave]

Thanks, I got it figured out. Overriding the paintComponent was the key thing I was missing. Seems to be working now.