Gif no longer animated after replacing with JLabel's setIcon method

I am still very new to Java and programming in general. I am trying to display a GIF using Swing and the following code:

    JPanel contentPane;
    JLabel imageLabel = new JLabel();

    public FrostyCanvas(String imageName) {
        try {
            setDefaultCloseOperation(EXIT_ON_CLOSE);
            contentPane = (JPanel) getContentPane();
            contentPane.setLayout(new BorderLayout());
            setSize(new Dimension(1600, 900));
            setTitle("FrostySpirit v1.1.1 (Beta) - FrostyCanvas");
            // add the image label
            ImageIcon ii = new ImageIcon(this.getClass().getResource(imageName));
            imageLabel.setIcon(ii);
            contentPane.add(imageLabel, java.awt.BorderLayout.CENTER);
            // display target GIF
            this.setLocationRelativeTo(null);
            this.setVisible(true);
        } catch (Exception exception) {
            exception.printStackTrace();
        }
    }

The method call is the following: (in a different class)

FrostyCanvas FC = new FrostyCanvas("old.gif");

The GIF is animated at this point. I then try to replace the GIF with another one using the following method: (in the same class as ForstyCanvas(String imageName))

public void changeGif(String imageName) throws IOException
    {
        Icon icon; File file;
        file = new File(imageName);
        icon = new ImageIcon(ImageIO.read(file));
        imageLabel.setIcon(icon);
    }

I call the method above in a different class using the following code:

FC.changeGif("D:\\new.gif")

The image is successfully replaced. However, now it only shows the very first frame of new.gif and is no longer animated. How can I make the new GIF move?

The way ImageIO reads the image is creating a static image. The thing to do is to use ImageIcon's loader.

ImageIcon replacement = new ImageIcon(file.toURI().toURL());

That way you are using the same method to construct the image icon as you do with the resource / url.