Java Swing

Chapter 4. Labels and Icons

We’ll begin our look at the Swing components with the JLabel class. In addition, we’ll look at Swing’s new Icon interface and an implementation of this interface called ImageIcon. With just these few new constructs, you’ll begin to see how much Swing has done to improve UI development in Java.

Labels

Swing allows you to create labels that can contain text, images, or both. We’ll begin this chapter with a look at the JLabel class.

The JLabel Class

The JLabel class allows you to add basic, nonfunctional labels to a user interface. Because of their inherent simplicity, there is no model class for JLabel components. Figure 4.1 shows a class diagram for JLabel. We’ll get into the two relations to Icon a little later.

Figure 4-1. JLabel class diagram

Unlike java.awt.Label objects, JLabel objects may consist of both text and graphics (icons). For simple text labels, the interface to JLabel is very similar to that of java.awt.Label. The code to create and display a very simple text label looks like this:

// 
               
               SimpleJLabelExample.java
//
import javax.swing*;

public class SimpleJLabelExample {
  public static void main(String[] args) {
    JLabel label = new JLabel("A Very Simple Text Label");

    JFrame frame = new JFrame();
    frame.addWindowListener(new BasicWindowMonitor());
    frame.getContentPane().add(label);
    frame.pack();
    frame.setVisible(true);
  }
}

Running this simple program ...