— Scott McNealy, Sun Microsystems Chairman, President and ceo

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chapter 13
Component 
is the more correct term for what we’ve been calling a widget. 
The things you put in a GUI. The things a user sees and interacts with. Text 
fields, buttons, scrollable lists, radio buttons, etc. are all components. In 
fact, they all extend
javax.swing.JComponent
. 
components and 
containers
Swing components
In Swing, virtually all components are capable of holding other 
components. In other words, you can stick just about anything into anything 
else. But most of the time, you’ll add user interactive components such as 
buttons and lists into background components such as frames and panels. 
Although it’s possible to put, say, a panel inside a button, that’s pretty 
weird, and won’t win you any usability awards. 
With the exception of JFrame, though, the distinction between interactive 
components and background components is artificial. A JPanel, for 
example, is usually used as a background for grouping other components, 
but even a JPanel can be interactive. Just as with other components, you 
can register for the JPanel’s events including mouse clicks and keystrokes.
Components can be nested
Four steps to making a GUI (review)
JFrame frame = new JFrame();
Make a window (a JFrame)
JButton button = new JButton(“click me”);
frame.getContentPane().add(BorderLayout.EAST, button);
1
Make a component (button, text field, etc.)
2
Add the component to the frame
3
frame.setSize(300,300);
frame.setVisible(true);
Display it (give it a size and make it visible)
4
Put 
interactive components
:
Into 
background components
:
JButton
JCheckBox
JTextField
JFrame
JPanel
A widget is technically 
a Swing Component. 
Almost every thing 
you can stick in a 
GUI extends from 
javax.swing.JComponent.

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