How to resize JLabel ImageIcon?

I'm making a Java Swing application that has the following layout (MigLayout):

[icon][icon][icon][....]
where icon = jlabel and the user can add more icons

When the user adds or removes icons, the others should shrink or grow.

My question is really straightforward: I have a JLabel which contains an ImageIcon; how can I resize this icon?

Try this :

ImageIcon imageIcon = new ImageIcon("./img/imageName.png"); // load the image to a imageIcon
Image image = imageIcon.getImage(); // transform it 
Image newimg = image.getScaledInstance(120, 120,  java.awt.Image.SCALE_SMOOTH); // scale it the smooth way  
imageIcon = new ImageIcon(newimg);  // transform it back

(found it here)

Resizing the icon is not straightforward. You need to use Java's graphics 2D to scale the image. The first parameter is a Image class which you can easily get from ImageIcon class. You can use ImageIcon class to load your image file and then simply call getter method to get the image.

private Image getScaledImage(Image srcImg, int w, int h){
    BufferedImage resizedImg = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);
    Graphics2D g2 = resizedImg.createGraphics();

    g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
    g2.drawImage(srcImg, 0, 0, w, h, null);
    g2.dispose();

    return resizedImg;
}

And what about it?:

ImageIcon imageIcon = new ImageIcon(new ImageIcon("icon.png").getImage().getScaledInstance(20, 20, Image.SCALE_DEFAULT));
label.setIcon(imageIcon);

From: https://stackoverflow.com/questions/16343098/resize-a-picture-to-fit-a-jlabel/32885963#32885963

This will keep the right aspect ratio.

	public ImageIcon scaleImage(ImageIcon icon, int w, int h)
	{
	    int nw = icon.getIconWidth();
	    int nh = icon.getIconHeight();

		if(icon.getIconWidth() > w)
	    {
	      nw = w;
	      nh = (nw * icon.getIconHeight()) / icon.getIconWidth();
	    }

	    if(nh > h)
	    {
	      nh = h;
	      nw = (icon.getIconWidth() * nh) / icon.getIconHeight();
	    }

	    return new ImageIcon(icon.getImage().getScaledInstance(nw, nh, Image.SCALE_DEFAULT));
	}

One (quick & dirty) way to resize images it to use HTML & specify the new size in the image element. This even works for animated images with transparency.

I agree this code works, to size an ImageIcon from a file for display while keeping the aspect ratio I have used the below.

/*
 * source File of image, maxHeight pixels of height available, maxWidth pixels of width available
 * @return an ImageIcon for adding to a label
 */


public ImageIcon rescaleImage(File source,int maxHeight, int maxWidth)
{
    int newHeight = 0, newWidth = 0;        // Variables for the new height and width
    int priorHeight = 0, priorWidth = 0;
    BufferedImage image = null;
    ImageIcon sizeImage;
    
    try {
            image = ImageIO.read(source);        // get the image
    } catch (Exception e) {
            
            e.printStackTrace();
            System.out.println("Picture upload attempted & failed");
    }
    
    sizeImage = new ImageIcon(image);
    
    if(sizeImage != null)
    {
        priorHeight = sizeImage.getIconHeight(); 
        priorWidth = sizeImage.getIconWidth();
    }

    // Calculate the correct new height and width
    if((float)priorHeight/(float)priorWidth > (float)maxHeight/(float)maxWidth)
    {
        newHeight = maxHeight;
        newWidth = (int)(((float)priorWidth/(float)priorHeight)*(float)newHeight);
    }
    else 
    {
        newWidth = maxWidth;
        newHeight = (int)(((float)priorHeight/(float)priorWidth)*(float)newWidth);
    }
    
   
    // Resize the image
    
    // 1. Create a new Buffered Image and Graphic2D object
    BufferedImage resizedImg = new BufferedImage(newWidth, newHeight, BufferedImage.TYPE_INT_RGB);
    Graphics2D g2 = resizedImg.createGraphics();
    
    // 2. Use the Graphic object to draw a new image to the image in the buffer
    g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
    g2.drawImage(image, 0, 0, newWidth, newHeight, null);
    g2.dispose();
    
    // 3. Convert the buffered image into an ImageIcon for return
    return (new ImageIcon(resizedImg));
}

I found that there is a minor edit to this fix from trolologuy on the last line of code, you will need to implement a new ImageIcon to get the code to compile properly (Yes I know this is 10 years ago). I found this to be an easy fix for a one off issue, but Suken Shah and Mr. Polywhirl have a better fix overall.

ImageIcon imageIcon = new ImageIcon("./img/imageName.png"); // assign image to a new ImageIcon
Image image = imageIcon.getImage(); // transform it 
Image newimg = image.getScaledInstance(120, 120,  java.awt.Image.SCALE_SMOOTH); // scale it smoothly  
ImageIcon newImageIcon = new ImageIcon(newimg);  // assign to a new ImageIcon instance