Swing I - Absolute Java - page 961

Self-Test Exercises

12. How would you modify the class definition in Display 17.6 so that the window
produced by the no-argument constructor is magenta instead of pink?
13. Rewrite the following two lines from Display 17.6 so that the label does not
have the name aLabel or any other name. Hint : Use an anonymous object.

JLabel aLabel = new JLabel("Close-window button works.");
add(aLabel);

Display 17.6 A JFrame with Color (part 1 of 2)

1 import javax.swing.JFrame;
2 import javax.swing.JLabel;
3 import java.awt.Color;

4 public class ColoredWindow extends JFrame
5 {
6

public static final int WIDTH = 300;

7 public static final int HEIGHT = 200;

8 public ColoredWindow(Color theColor)
9 {

10 super ("No Charge for Color");
11 setSize(WIDTH, HEIGHT);
12 setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

13 getContentPane().setBackground(theColor);

14 JLabel aLabel = new JLabel("Close-window button works.");
15 add(aLabel);
16 }
17 public ColoredWindow()
18 {
19

This is an invocation of the
other constructor.

this (Color.BLUE);

20 }
21 }

This is the file ColoredWindow java .

1 import java.awt.Color;

This is the file ColoredWindow java .

2 public class DemoColoredWindow
3 {
4 public static void main(String[] args)
5 {
6 ColoredWindow w1 = new ColoredWindow();
7 w1.setVisible( true );

8 ColoredWindow w2 = new ColoredWindow(Color.GRAY);
9 w2.setVisible( true );
10 }
11 }

(continued)