You can draw things on the screen, but there are things
that have already been made for you to put on the screen.
These are called components. An example
of a component is a label, button or scrollbar.
The Java Swing classes provide the tools
that help you build a good graphical user interface.
You've already used some of the drawing methods.
In this section you will learn to use Swing components.
Some advantages of using
these components are:
Java has already defined them along with
a number of methods for customizing them.
They paint themselves with
their own paintComponent method, and redraw themselves as
necessary when their state changes.
position and resize themselves depending on the layout.
Most allow user interaction which can result in
calls to your methods to process the input.
Defining your own components
The predefined Java components are adequate for all normal programming, with the
one exception of drawing graphical output. In this case you want to define your
own "component" that draws itself, which is easily done with a subclass of JPanel
and overriding the default paintComponent method.
Some of the kinds of components that you will learn to use
are JLabel, JTextField, and JButton.