The Label class and the other components you'll learn about today
are heavyweight components based on peers. Peers are
native graphical user interface widgets. For instance, when Java is
asked to draw a label it doesn't just draw a string in the right
place on the screen. It creates whatever the native GUI's concept
of a Label component is and puts that on the screen. This means
that a label looks like a Windows label on Windows; a label looks
like a Mac label on the Mac; a label looks like a Motif label on
Motif, and so on.
One problem with this aproach is that not all GUIs support
changing the fonts, colors, and so on of their native peers.
Another problem is that this approach adds an additional level of
indirection that cuts into performance. An alternate approach is to
implement only very basic graphics primitives like
drawString() and drawLine() in native code,
then draw the components like buttons and labels using those
graphics primitives.
In Java 1.2 and later the javax.swing
package provides a set of classes that do exactly this. The Swing
classes provide parallels to many standard AWT components with
different names but similar or expanded interfaces. For instance, a
JLabel is the Swing equivalent of a
java.awt.Label. A JButton is the Swing
equivalent of a java.awt.Button. Swing also includes
some additional GUI widgets that are not available in the standard
AWT, a tree control for example.