New Program

A JButton generates actionEvents and needs an ActionListener that implements actionPerformed(). The actionPerformed() method can call System.exit(0) to exit the program.

Let us write a program that:

• Has a frame that contains a button.
  • The frame will be the listener for the button.
  • The frame will implement ActionListener.
  • It will have an actionPerformed() method.
• Clicking on the button will exit the program.
  • The actionPerformed() method calls System.exit(0).
• The program will not have a listener for window events.
  • Clicking on the "close button" of the frame will not exit the program.

Often a real application has several ways to quit: the close window button, a menu selection, and perhaps a button like this program.