Question

First I used JLabel and ImageIcon. It worked fine. However, the image doesn’t show up when I exported it to JAR.
So, then I created my own ImagePanel and used the drawImage method to display it.
But it terminates and throws an

exception in thread “main” java.lang.IllegalArgumentException: input
== null!

well, my code follows below..

startMenu

public class startMenu extends JFrame{
  ...
  URL imgUrl = getClass().getResource("images/contacts.png");

  public startMenu(){
    ...
    ImagePanel imgPanel = new ImagePanel(imgUrl);
  }

}

ImagePanel

public class ImagePanel extends JPanel{

    private Image image;
    private URL imgUrl;

 public ImagePanel(URL url){
        this.imgUrl= url;

        try{    
            image = ImageIO.read(imgUrl);
        } 
        catch (IOException e) {
            System.out.println("no such file");
        }
    }

 @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        if(image!=null){
             g.drawImage(image, 10, 12, 128, 128, this);
        }
        else{
            g.drawImage(image, 0, 0, this);
        }
    }

    @Override
    public Dimension getPreferredSize() {
       return new Dimension(150,150);
    }
}

If I would use ImageIcon with an imageUrl. It shows the same error message.

  URL imgUrl = getClass().getResource("images/contacts.png");
    private ImageIcon adBook = new ImageIcon(imgUrl);
    private JLabel mainImg = new JLabel(adBook);

Answer 1

problem is where the Images are located. I always saved the images directly inside the directory where “src” and “bin” are. “but getClass().getResource(“…”)” returns the path of bin. So I just had to move the image folder into “src” , so it will automatically make a copy of this directory into ‘bin’. problem solved.

URL imgUrl = getClass().getResource("images/contacts.png");

returns–> Q:\workspace\project name\bin\images\contacts.png