How do I load an image in a Swing application?

The easiest way to do this is to use Swing's ImageIcon class. For example

ImageIcon i = new ImageIcon("mypic.gif");

You can then use the icon in many Swing components, like a JButton:

JButton b = new JButton(i);

Note that it's generally a good idea to use Class.getResource() to find the image file rather than directly use the file name as above. This allows you to put the image anywhere on your CLASSPATH. For example:

URL picURL = getClass().getResource("mypic.gif");
ImageIcon i = new ImageIcon(picURL);

In this case, the pic would be in the CLASSPATH under the directory structure of the current class' package. For example, if you had

package my.funky.stuff;

import javax.swing.ImageIcon;
import javax.swing.JButton;
import java.net.URL;

public class SomeClass {
  public SomeClass() {
    URL picURL = getClass().getResource("mypic.gif");
    ImageIcon i = new ImageIcon(picURL);
    JButton b = new JButton(i);
  }
}

my/funky/stuff/mypic.gif

URL picURL = getClass().getResource("/mypic.gif");