GUI BASICS - Introduction to Java Programming - page 459

The Swing version of panel is JPanel . You can use new JPanel() to create a panel with
a default FlowLayout manager or new JPanel(LayoutManager) to create a panel with
the specified layout manager. Use the add(Component) method to add a component to the
panel. For example, the following code creates a panel and adds a button to it:

JPanel p = new JPanel();
p.add( new JButton( "OK" ));

Panels can be placed inside a frame or inside another panel. The following statement places
panel p in frame f :

f.add(p);
Listing 12.6 gives an example that demonstrates using panels as subcontainers. The program
creates a user interface for a microwave oven, as shown in Figure 12.10.

Frame

Content panel

Button

Panel p2

Panel p1

F IGURE 12.10

The program uses panels to organize components.

L ISTING 12.6 TestPanels.java
1 import java.awt.*;

2 import javax.swing.*;

3
4 public class TestPanels extends JFrame {

5 public TestPanels() {

6 // Create panel p1 for the buttons and set GridLayout

7
8
9
10 // Add buttons to the panel
11 for ( int i = 1 ; i <= 9 ; i++) {
12

JPanel p1 = new JPanel();

panel p1

p1.setLayout( new GridLayout( 4 , 3 ));

p1.add ( new JButton( "" + i));

13 }
14
15 p1.add( new JButton( "" + 0 ));
16 p1.add( new JButton( "Start" ));
17 p1.add( new JButton( "Stop" ));
18
19

// Create panel p2 to hold a text field and p1

20
21 ( new JTextField( "Time to be displayed here" ),
22 BorderLayout.NORTH);
23

JPanel p2 = new JPanel( new BorderLayout()); panel p2

p2.add

p2.add (p1, BorderLayout.CENTER);

24
25 // Add contents to the frame
26 add(p2, BorderLayout.EAST);
27 add( new JButton( "Food to be placed here" ),
28 BorderLayout.CENTER);
29 }
30

add p2 to frame