Resizing an image using buttons and JPanel

I'm trying to make an image of a cake pop up on a button when you click a different button.

The part of the code I'm working on. I just want to resize the button.

if (e.getSource() == cake) {
    BufferedImage myPicture = null;
    try {
        myPicture = ImageIO.read(new File("cake.jpg"));
        myPicture.getScaledInstance(800, 500, Image.SCALE_DEFAULT);
    } catch (IOException e1) {
        e1.printStackTrace();
    }
    JLabel picLabel = new JLabel(new ImageIcon(myPicture));
    cake.add(picLabel, BorderLayout.CENTER); 
}

I tried scaling the image as shown and done other stuff from looking at other stack overflow and other websites but non of them have worked.

Like @g00se mentioned:

Creates a scaled version of this image. A new Image object is returned ...

So you need to assign its value back to myPicture variable like this:

myPicture = myPicture.getScaledInstance(800, 500, Image.SCALE_DEFAULT);

By the way, this is a nice way to scale a picture but using AffineTransform is much faster if you prefer. Here is the method I use for scaling images:

/**
  * Scales the given image by the specified ratio 
  * using the AffineTransform method.
  *
  * @param source the original BufferedImage to be scaled.
  * @param ratio  the scaling ratio. A ratio greater than 1 
  * enlarges the image, less than 1 shrinks the image.
  * @return a new BufferedImage that is a scaled version of
  * the original image.
  */
private BufferedImage scaleImageFast(BufferedImage source, double ratio) {
    BufferedImage bi = new BufferedImage(
            (int) (source.getWidth() * ratio),
            (int) (source.getHeight() * ratio),
            BufferedImage.TYPE_INT_ARGB);
    Graphics2D g2d = bi.createGraphics();
    AffineTransform at = AffineTransform.getScaleInstance(ratio, ratio);
    g2d.drawRenderedImage(source, at);
    g2d.dispose();
    return bi;
}

Also if the image is located on your res folder you should use getResourcesAsStream() method like this:

ImageIO.read(MyClass.class.getResourceAsStream("cake.jpg"));