A Java program to open, read, and display an image file

In an earlier blog post I shared a small section of Java code that showed how to place an image on a JLabel. When I just looked back at that post I thought it would be cool if I showed a complete Java program that could read an image from the local filesystem, create a BufferedImage from that image file, create an ImageIcon from that image, place that ImageIcon on a JLabel, and finally show the image in a JFrame.

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Java program to show an image in a JFrame

To that end, here's the complete Java Swing source code for a program that does all those things, eventually displaying the image you provide in a JFrame:

import java.awt.*;
import java.awt.image.*;
import java.io.*;
import javax.imageio.*;
import javax.swing.*;

/**
 * A Java class to demonstrate how to load an image from disk with the
 * ImageIO class. Also shows how to display the image by creating an
 * ImageIcon, placing that icon an a JLabel, and placing that label on
 * a JFrame.
 * 
 * @author alvin alexander, alvinalexander.com
 */
public class ImageDemo
{
  public static void main(String[] args) throws Exception
  {
    new ImageDemo(args[0]);
  }

  public ImageDemo(final String filename) throws Exception
  {
    SwingUtilities.invokeLater(new Runnable()
    {
      public void run()
      {
        JFrame editorFrame = new JFrame("Image Demo");
        editorFrame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        
        BufferedImage image = null;
        try
        {
          image = ImageIO.read(new File(filename));
        }
        catch (Exception e)
        {
          e.printStackTrace();
          System.exit(1);
        }
        ImageIcon imageIcon = new ImageIcon(image);
        JLabel jLabel = new JLabel();
        jLabel.setIcon(imageIcon);
        editorFrame.getContentPane().add(jLabel, BorderLayout.CENTER);

        editorFrame.pack();
        editorFrame.setLocationRelativeTo(null);
        editorFrame.setVisible(true);
      }
    });
  }
}
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To compile this program

To compile this program, simply download it to your computer, save it with the filename ImageDemo.java, and then compile it with the following command:

javac ImageDemo.java

Because I did not specify a package name at the beginning of the class definition, you can do this from your current directory.

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To run the program

After you compile the program, you can run it like this:

java ImageDemo path-to-your-image

For instance, if you have a file named foo.jpg in the current directory, you will run this program like this:

java ImageDemo foo.jpg

Or, if you're on a Mac or Unix system and the same file is in the tmp directory, you will run the program like this:

java ImageDemo /tmp/foo.jpg

This is a simple program, but if you're new to Java and working with images, I hope having a complete program like this is helpful.

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