1
2
3
4
5
6import java.util.Vector;
7
8public
9class Counter {
10 int cnt;
11
12 public
13 Counter() {
14 this.cnt = 0;
15 counterChangedListeners = new Vector();
16 }
17
18
19
20 public
21 void incr(int i) {
22 cnt += i;
23
24 notifyCounterChanged();
25 }
26
27
28
29
30 private
31 Vector counterChangedListeners;
32
33 protected
34 void notifyCounterChanged() {
35 Vector l;
36 CounterChangedEvent e = new CounterChangedEvent(this,cnt);
37
38 synchronized (this) {
39 l = (Vector)counterChangedListeners.clone();
40 }
41
42 for ( int i = 0;
43 i < l.size();
44 ++i ) {
45 ((CounterChangedListener)l.elementAt(i)).counterChanged(e);
46 }
47 }
48
49
50
51 public
52 synchronized
53 void addCounterChangedListener(CounterChangedListener l) {
54 counterChangedListeners.addElement(l);
55 }
56
57 public
58 synchronized
59 void removeCounterChangedListener(CounterChangedListener l) {
60 counterChangedListeners.removeElement(l);
61 }
62}
