How to repaint a java.awt.Window?

Question

why is my java.awt.Window not repainting after I called the repaint() method?

public class Counter extends Window implements ActionListener {

private static final long serialVersionUID = 1L;
private Timer timer;
private int time;

public Counter() {
    super(null);
    setAlwaysOnTop(true);
    setBounds(getGraphicsConfiguration().getBounds());
    setBackground(new Color(0, true));
    setVisible(true);
    timer = new Timer(1000, this);
    timer.start();
}

@Override
public void paint(Graphics g) {
    super.paint(g);
    g.clearRect(0, 0, getWidth(), getHeight());
    g.setColor(Color.RED);
    g.drawString(String.valueOf(time), getWidth()/2, getHeight()/2);
}

@Override
public void update(Graphics g) {
    super.update(g);
}

@Override
public void actionPerformed(ActionEvent e) {
    time++;
    repaint();
}

As you can see i created a timer with a delay of 1 second. After that i call repaint() to draw the counter's number on the screen. But it only draws a zero on my screen and stops drawing then (the zero stays on screen). First i thought that the paint method is only called once, but i tested a System.out.prinln() and prooved that the paint method is executed every second so it should actually repaint the window... So i don't know where i made a mistake.

And yes it is my intention to use the awt.Window and not a JFrame or Frame etc..

Are you sure your actionperformed method is being called? In your println() inside paint print your time variable to make sure it is being updated at all — Gordon Allocman, Mar 30 '16 at 19:53
@GordonAllocman yep sir, actionperformed is called, i tested it, time is also counting 0,1,2,3.... — AvarionDE, Mar 30 '16 at 19:57
Call explictily to "invalidate" method for this component. That forces a repaint because invalidates the whole containter (and forces re-layout components in it). — Jorge, Mar 30 '16 at 20:03
@Jorge Unfortunately invalidate() has no effect, paint() isn't called after invalidate(), as well. — AvarionDE, Mar 30 '16 at 20:09
Check this solution http://stackoverflow.com/questions/8853397/repaint-in-java — Jorge, Mar 30 '16 at 20:16
@Jorge in this case the user used a JComponent but there's no getContenPane() method for awt Window. I also tried validate — AvarionDE, Mar 30 '16 at 20:22
@Jorge validate, invalidate, revalidate have little to do with the repaint cycle of the component and elate only to how the container hierarchy layout is updated, you'd still need to repaint the component for the effect to take place — MadProgrammer, Mar 30 '16 at 20:43
@AvarionDE Yep, no issues. Personally not the way I'd do it, but it runs and updates — MadProgrammer, Mar 30 '16 at 20:57
@MadProgrammer wow, i also tried to run it in console without eclipse and it only draws the zero again. thats weird and frustrating — AvarionDE, Mar 30 '16 at 21:03

score 2 · Accepted Answer · edited Mar 31 '16 at 07:39

I finally got to run the code on Windows 7, and I could replicate the issue. For some reason, paint isn't being called; why, I don't know. Because I wouldn't do it this way, I've never had that issue.

Instead, I'd start by having the counter class extend from something JPanel or JComponent (just remember to make JPanel transparent) and then add it to a JWindow, something like this:

import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JPanel;
import javax.swing.JWindow;
import javax.swing.Timer;


public class Counter extends JPanel implements ActionListener {

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                JWindow window = new JWindow();
                window.add(new Counter());
                window.pack();
                window.setLocationRelativeTo(null);
                window.setBackground(new Color(0, 0, 0, 0));
                window.setVisible(true);
            }
        });
    }

    private static final long serialVersionUID = 1L;
    private Timer timer;
    private int time;

    public Counter() {
        setOpaque(false);
        timer = new Timer(1000, this);
        timer.start();
    }

    @Override
    public Dimension getPreferredSize() {
        return new Dimension(200, 200);
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g); //To change body of generated methods, choose Tools | Templates.
        System.out.println(time);
        g.clearRect(0, 0, getWidth(), getHeight());
        g.setColor(Color.RED);
        g.drawString(String.valueOf(time), getWidth() / 2, getHeight() / 2);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        time++;
        System.out.println("..." + time);
        repaint();
    }
}

How to repaint a java.awt.Window?

1 Answers1