Java Foundation Classes in a Nutshell

A Simple Graphical User Interface

Example 2-1 is a simple program that uses Swing to create and display a graphical

user interface. Figure 2-1 shows the GUI created by this program.

Figur e 2−1: The GUI of the DisplayMessage program

The

DisplayMessage pr ogram is designed for use in a shell script or batch file.

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If

you invoke the program on the command line with the text of a question, it dis-

plays the question to the user and waits for the user to click the Yes button or the

No button. The program sets its exit code based on the user’s response, so a shell

script can examine this exit code to determine how the user responded. The pro-

gram expects from one to three command-line arguments that specify the text of

the question and the text for the “Yes” and “No” buttons, respectively. For exam-

ple, you might invoke the program like this:

% java DisplayMessage "Do you really want to quit?" "Yes, Please", "No, Thanks"

The example illustrates step-by-step how to create a Swing GUI. Don’t worry if

you don’t understand the details of this program yet. If you read it through once

now to get the big picture, you can refer back to it as you read the sections that

follow.

Example 2−1: Cr eating a Simple GUI with Swing

import java.awt.*; // AWT classes

import javax.swing.*; // Swing components and classes

import javax.swing.border.*; // Borders for Swing components

import java.awt.event.*; // Basic event handling ...