My JFrame doesn't show anything

image, java, jframe, loading, swing

Solution

Something may be wrong with your with your String path. What you should do though, instead o reading a file, you should be reading a URL, loading from the class path. At time of deployment, you'll find out that the file path won't work, so it's better to package your image as an embedded resource, putting the image in the class path. I had no problems when doing this. Here's what I did.

Change the path to a path relative to my class path

World w = new World("Hej", "/resources/stackoverflow5.png", 1024, 768);

Changed loading from a file to loading from a URL from my class path

background = new ImageIcon(SpritePanel.class.getResource(bgPath));

Put the image in `resources` package in my class path

Everything works fine

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Graphics;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import static javax.swing.JFrame.EXIT_ON_CLOSE;
import javax.swing.JLabel;
import javax.swing.JPanel;

public class Implementation {

    public static void main(String[] args) {
        World w = new World("Hej", "/resources/stackoverflow5.png", 1024, 768);
    }
}

class World extends JFrame {

    private static final long serialVersionUID = 1L;
    private SpritePanel spritePanel;
    private JPanel bottom;
    private int width;
    private int height;

    public World(String windowCaption, String bgPath, int width, int height) {
        super(windowCaption);

        spritePanel = new SpritePanel(bgPath);
        add(spritePanel, BorderLayout.CENTER);
        System.out.println(spritePanel);

        bottom = new JPanel();
        bottom.add(new JLabel("Hej"));
        add(bottom, BorderLayout.SOUTH);

        Dimension size = new Dimension(width, height);
        setSize(size);
        setLocationRelativeTo(null);
        setDefaultCloseOperation(EXIT_ON_CLOSE);

        pack();
        setVisible(true);

        validate();
        repaint();
    }

    class SpritePanel extends JPanel {

        private static final long serialVersionUID = 1L;
        private ImageIcon background;
//private ArrayList<Sprite> sprites = new ArrayList<Sprite>();

        public SpritePanel(String bgPath) {
            background = new ImageIcon(SpritePanel.class.getResource(bgPath));
            setLayout(null);
            Dimension size = new Dimension(background.getIconWidth(), background.getIconHeight());
            setPreferredSize(size);
            setMaximumSize(size);
            setMinimumSize(size);
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            g.drawImage(background.getImage(), 0, 0, this);
            System.out.println("painted panel");
        }
    }
}

Side Notes

- No need to `setSize()`. You already `pack()`. It better to just pack anyway.

- Put the `pack()` before the `setLocationRelativeTo()`. If you `pack()` after, you'll notice your frame won't be in the desired location.

Run your Swing apps from the Event Dispatch Thread (EDT) like this

public static void main(String[] args){
    SwingUtilities.invokeLater(new Runnable(){
        @Override
        public void run() {
            new World("Hej", "/resources/stackoverflow5.png", 1024, 768);
        }
    });
}

If you want to make the frame fill the screen, don't set the size. Different machines have different screen sizes. Instead use `setExtendedState(JFrame.MAXIMIZED_BOTH);`

- Also, your `setSize()` won't work anyway because you're calling `pack()` after.

Problem

Original source