Java Swing, 2nd Edition

Working with Images

JLabels make it very simple to add graphics to your user interface. Images used in JLabels (and also in other Swing components, such as buttons) are of type javax.swing.Icon, an interface described in detail in the next section.

These two lines of code show how simple it is to create a label containing an image:

ImageIcon icon = new ImageIcon("images/smile.gif");
JLabel label = new JLabel(icon);

For labels that contain both graphics and text, Swing provides considerable flexibility with respect to the relative location of the text and image. The text for the label may be displayed at any one of nine locations relative to the image. These locations are specified via the setVerticalTextPosition( ) and setHorizontalTextPosition( ) methods, which take values from the SwingConstants class discussed earlier. Note the distinction between the label’s text position and its alignment; text position reflects the position of the text relative to the image while alignment specifies the location of the label’s contents (image and text) relative to the borders of the label.

Another useful feature of the JLabel class is the ability to enable and disable the label by “graying out” the label and text. By default, a call to JLabel.setEnabled(false) switches the image to an automatically generated grayscale version of the original image and alters the text rendering in some (L&F-specific) way. However, the grayscale image is used only if no disabled icon has been set. The setDisabledIcon( ...