Prentice.Hall.Introduction.to.Java.Programming,.Brief.Version.9th.(2014).[sharethefiles.com]

60
61 /** Remove an action event listener */
62 public synchronized void removeActionListener(ActionListener l) {
63 if (actionListenerList != null && actionListenerList.contains(l))
64 actionListenerList.remove(l);
65 }
66
67 /** Fire TickEvent */
68 private void processEvent(ActionEvent e) {
69 ArrayList list;
70
71 synchronized (this) {
72 if (actionListenerList == null) return;
73 list = (ArrayList)(actionListenerList.clone());
74 }
75
76 for (int i = 0; i < list.size(); i++) {
77 ActionListener listener = list.get(i);
78 listener.actionPerformed(e);
79 }
80 }
81 }
NOTE
The registration/deregistration/processEvent methods
(lines 54-80) are the same as in lines 49-82 in Listing
27.2, CourseWithActionEvent.java. If you use a GUI
builder tool such as NetBeans and Eclipse, the code can
be generated automatically.
The UML diagram for CircleView is shown in Figure 39.4 and its
source code is given in Listing 39.2. The view listens for
notifications from the model. It contains the model as its
property. When a model is set in the view, a listener is created
and registered with the model (lines 13-17). The view extends
JPanel and overrides the paintComponent method to draw the circle
according to the property values specified in the model.
javax.swing.JPanel
CircleView
-model: CircleModel
JavaBeans properties with ge t a nd set
methods omitted in the UML diagram
Stores the circle model.
#paintComponent(g: Graphics): void Paints the view.
Figure 39.4
The view displays the circle according to the model.
Listing 39.2 CircleView.java
1 import java.awt.*;
2 import java.awt.event.*;
3
4 public class CircleView extends javax.swing.JPanel {
5 private CircleModel model;
5