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3.11. Icons

All buttons, labels, and menu items in Swing can display both text and graphic elements. If you are familiar with the AWT, you might expect Swing to use the java.awt.Image class to represent these graphic elements. Instead, however, it uses javax.swing.Icon. This interface represents a graphic element more generally. Its paintIcon() method is called to display the graphic, and this method can do anything necessary to display it.

Swing includes an Icon implementation called ImageIcon. This commonly used class is an Image-based implementation of Icon. ImageIcon also simplifies the process of reading images from external files. One of the constructors for ImageIcon simply takes the name of the desired image file.

A related utility function is the static method GrayFilter.createDisabledImage(). This version produces a grayed-out version of a given Image, which can be used to create an ImageIcon that represents a disabled action or capability.

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