ImageIcon.paintIcon does not draw image on JPanel

Question

I'm trying to draw a .png on a JPanel. I imported it using an ImageIcon constructor, and drew it in my custom panel's paintComponent.

My sscce:

package mypackage;

import java.awt.Graphics;

import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class MyPanel extends JPanel {

    static JFrame frame;
    static MyPanel panel;
    static ImageIcon icon;

    public static void main(String[] args) {
        icon = new ImageIcon(MyPanel.class.getResource("MyImage.png"));
        frame = new JFrame();
        panel = new MyPanel();
        frame.setSize(500, 500);
        frame.add(panel);
        frame.setVisible(true);
        frame.repaint();
    }

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        icon.paintIcon(panel, g, 100, 100);
    }
}

I expected the image, which is just a couple shapes on a white background, to display at (100, 100) on the panel. Instead, a blank screen:

The fact that no error occurs means the program is finding the file properly.

The image is in my Eclipse project in the same package as the class:

Why is this happening? How do I fix it?

Don't create the ImageIcon in your paintComponent method. Also try just drawing a circle or something in your panel. — matt, Oct 27 '15 at 14:38
@matt Moving `icon = new ImageIcon(MyPanel.class.getResource("MyImage.png"));` to `main` and adding `static ImageIcon icon` above `main` does not fix the problem. — snickers10m, Oct 27 '15 at 14:40
@matt Additionally, adding `((Graphics2D) g).draw(new Ellipse2D.Double(100, 100, 100, 100));` to `paintComponent` successfully draws a circle. — snickers10m, Oct 27 '15 at 14:41
It seems as though your image icon has not been loaded properly. — matt, Oct 27 '15 at 14:41
For example, you have the png file in your source. It needs to be in your classpath. — matt, Oct 27 '15 at 14:43
@Reimeus Apologies. That's not what my question was about, and it has absolutely no effect, but I'll change my code to adhere to a better approach. — snickers10m, Oct 27 '15 at 14:44
@matt Is there a way I could find out what is in my icon? There aren't any errors occuring and the URL is valid, so I do really think the image is loading. — snickers10m, Oct 27 '15 at 14:48
The URL being valid doesn't mean much. You can get the height and width and make sure that is correct. You can create a BufferedImage img = ImageIO.read(MyPanel.class.getResourceAsStream("MyImage.png")); — matt, Oct 27 '15 at 14:52
@matt The width and height are both -1, so you're right. The image isn't loading. If you'd like to post that classpath fact as an answer as well as your workaround with BufferedImage I'd gladly accept it. — snickers10m, Oct 27 '15 at 14:55

score 3 · Accepted Answer · edited May 23 '17 at 12:03

As the code looks correct, I suggest that the resource is not being loaded correctly.

Place the png file in your classpath. Eg. I would have a directory:

~/ProjectRoot/resources/mypackage/

Then include resources in the classpath. In eclipse you can setup the classpath via

Project -> Properties -> Java Build Path -> Add Class Folder

BufferedImage img = 
    ImageIO.read(MyPanel.class.getResourceAsStream("MyImage.png"));

That throws an exception if the image isn't found. You can use it to make an ImageIcon.

score 2 · Answer 2 · answered Oct 27 '15 at 15:06

When you use ImageIcon to read an image from a file, you get no indication whether or not the read was successful.

Here's your GUI where I read an image using ImageIO:

And here's the image, in the same directory as the Java source:

Here's your code, where I used an ImageIO read to read an Image, and draw the image in the paintComponent method.

package com.ggl.testing;

import java.awt.Graphics;
import java.awt.Image;
import java.io.IOException;

import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class MyPanel extends JPanel {

    private static final long serialVersionUID = -9008812738915944216L;

    private static JFrame frame;
    private static MyPanel panel;
    private static Image image;

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                image = getImage();
                frame = new JFrame();
                panel = new MyPanel();
                frame.setSize(500, 500);
                frame.add(panel);
                frame.setVisible(true);
            }
        });
    }

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        g.drawImage(image, 100, 100, MyPanel.this);
    }

    private static Image getImage() {
        Image image = null;
        try {
            image = ImageIO.read(MyPanel.class.getResource("maze.jpg"));
        } catch (IOException e) {
            e.printStackTrace();
        }
        return image;
    }
}

ImageIcon.paintIcon does not draw image on JPanel

2 Answers2