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The JPanel class

Textbook: Section 12.6

A JPanel object is an empty graphical component. It may seem weird that such a thing is worth talking about. But it is, for two reasons:

• By extending the JPanel class, you can define your own custom component. For example, Logisim (the logic circuit simulator used in CSCI 150) extends JPanel to create the canvas on which the user can draw a circuit. This is an advanced topic, which we're not going to discuss today. (You can read about it on the class handouts Web page.)

• A JPanel is a subclass of Container, which means you can add other components into it.

There are three JPanel methods that are particularly important.

JPanel()

Creates an empty JPanel.

void add(Component what)

Inserts what into the panel, using the default placement.

void add(Component what, Object info)

Inserts what into the panel, using info as information about where the object should be placed.

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