Java How to Program Fourth Edition - DCC

742 Graphical User Interface Components: Part 2 Chapter 13
java DrawShapes 600 400
contains two command-line arguments—600 and 400—that specify the width and height
of the application window. Java passes the command-line arguments to main as the array
of Strings called args, which we have declared in the parameter list of every application’s
main method, but not used until this point. The first argument after the application
class name is the first String in the array args, and the length of the array is the total
number of command-line arguments. Line 60 begins the definition of main and declares
array args as an array of Strings that allows the application to access the command-line
arguments. Line 62 defines variables width and height that are used to specify the size
of the application window.
1 // Fig. 13.9: DrawShapes\.java
2 // Draw random lines, rectangles and ovals
3
4 // Java core packages
5 import java.awt.*;
6 import java.awt.event.*;
7
8 // Java extension packages
9 import javax.swing.*;
10
11 public class DrawShapes extends JApplet {
12 private JButton choices[];
13 private String names[] = { "Line", "Rectangle", "Oval" };
14 private JPanel buttonPanel;
15 private DrawPanel drawingPanel;
16 private int width = 300, height = 200;
17
18 // initialize applet; set up GUI
19 public void init()
20 {
21 // set up DrawPanel
22 drawingPanel = new DrawPanel( width, height );
23
24 // create array of buttons
25 choices = new JButton[ names.length ];
26
27 // set up panel for buttons
28 buttonPanel = new JPanel();
29 buttonPanel.setLayout(
30 new GridLayout( 1, choices.length ) );
31
32 // set up buttons and register their listeners
33 ButtonHandler handler = new ButtonHandler();
34
35 for ( int count = 0; count < choices.length; count++ ) {
36 choices[ count ] = new JButton( names[ count ] );
37 buttonPanel.add( choices[ count ] );
38 choices[ count ].addActionListener( handler );
39 }
Fig. Fig. 13.9 13.9 Creating a GUI-based application from an applet (part 1 of 4).