Why is my gif animation in paintComponent not working?

Question

I am creating a Java game, and in this, I have a plane that can be moved around by the user, however if the plane hits any of the sides, it should explode - meaning there should be an explosion at that location. I used links such as: Why gif animation doesn't animate when using it in paintComponent()? and other ones to find out how to animate a gif, however, my code doesn't work.

Here is the relevant code:

            ImageIcon ii = new ImageIcon(this.getClass().getResource("explosion.gif"));
            Graphics2D g2d = (Graphics2D)g;
            
            g2d.drawImage(ii.getImage(), planeX, planeY, this);
            System.out.println("drawn");

Although "drawn" is being printed out on the console, the explosion gif doesn't load. I checked the file name and it was correct. However, I did use the same gif somewhere else in my code and it worked there, so is there something that prevents having a gif being used twice in Java?

Here is my entire paintComponent() method:

        super.paintComponent(g);
        
        setFocusable(true);
        requestFocus();
        
        background = new ImageIcon("bg.png").getImage();
        g.drawImage(background, -6, 0, 700, 700, null); //background of JPanel
        
        if (!hit) g.drawImage(plane, planeX, planeY, planeLen, planeHei, null);  //only draw plane if not exploded
        else if (count == 0) 
        {
            ImageIcon ii = new ImageIcon(this.getClass().getResource("explosion.gif"));
            Graphics2D g2d = (Graphics2D)g;
            
            g2d.drawImage(ii.getImage(), planeX, planeY, this); //doesn't work
            System.out.println("drawn"); //printed
        }

        title = new ImageIcon("title.png").getImage(); //transparent, is drawn
        g.drawImage(title, -9, 20, 700, 218, null);
        
        title2 = new ImageIcon("title2.png").getImage(); //transparent, is drawn
        g.drawImage(title2, 10, 245, 670, 20, null);

I have checked title and title2 and they are transparent, meaning that the explosion should be seen. I even tried it below those two images, and the explosion still is not visible. I am using JButtons and KeyListeners on this panel as well.

Please let me know if I should add anything else, and thank you in advance!

Answer 1

You should always pass this as the final argument to drawImage in a painting method. If an image has multiple frames, or the image is loaded in the background, this tells the component to paint itself again as more of the image becomes available.

Painting of components happens frequently. It is controlled by the system, not just by code calling the component’s repaint methods. In fact, it’s common for painting to happen many times per second. Many system events beyond a programmer’s control can trigger painting, such as a user moving a window, or another window moving, or even the user moving the mouse.

For this reason, painting should not perform slow operations like loading files. Move the loading of your images out of your painting method, and into the class’s constructor. Store the Image objects in private fields, where paintComponent can use them again and again without reloading them for every painting run.

Since the timing of painting is beyond your control, it is important that you never change the state of a component in a painting method. Move setFocusable and requestFocus out of your paintComponent method. Those calls should be in the code that builds your component and adds it to a window.

Finally, be aware that loading images from files will not work if you ever package your application in a .jar file. A .jar file is a single compressed archive; the entries in it are not files anymore, they’re just sequences of bytes inside the archive. Loading all files using getResource will address this, since getResource looks in every .jar file in the classpath.

Answer 2

Never mind, I had to make a duplicate of "explosion.gif". It works fine now! However, please let me know if there is another way of doing this, much faster AND efficiently. Thanks!