Question

I am programming in java and I’m getting into GUIs and Graphics. In my program I paint an image onto a JPanel and add the JPanel to the main window. The Problem I’m having is when I run the program the image doesn’t show until I manually resize the window. Here is the relevant code:

Where the image is drawn:

public class painting extends JPanel{
    public void paintComponent(Graphics g){
        super.paintComponent(g);
        this.setBackground(Color.WHITE);
        g.drawImage(Toolkit.getDefaultToolkit().getImage("image.png"), 0, 0, null);
    }
}

Where JPanel is added to JFrame (c is GridBagConstraints):

public class GUI extends JFrame{
    public GUI(){
        painting Pnt = new painting();
        c.gridx = 1;    c.gridy = 0;
        c.ipadx = 540;  c.ipady = 395;
        add(Pnt, c);        
    }
}

Where The Window is set up:

public class MainC{
    public static void main (String args[]){
        GUI gui = new GUI();
        gui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        gui.pack();
        gui.setVisible(true);
        gui.setTitle("Title");
    }
}

Thanks,
Bennett

EDIT: I noiced that it sometimes displays the image correctly but then if I close the program and try again and it doesn’t work until I resize it.

EDIT2: Here are the files GUI class, MainC class

Answer 1

Toolkit.getImage() works asynchronously. Either use ImageIO.read() or add a MediaTracker.