Java Reference
In-Depth Information
Display 19.3
The
Runnable
Interface
(part 2 of 2)
39
public
void
actionPerformed(ActionEvent e)
40
{
41
startThread();
42
}
43
public
void
run()
44
{
45
Graphics g = box.getGraphics();
46
for
(
int
y = 0; y < FILL_HEIGHT; y = y + CIRCLE_SIZE)
47
for
(
int
x = 0; x < FILL_WIDTH; x = x + CIRCLE_SIZE)
48
{
49
g.fillOval(x, y, CIRCLE_SIZE, CIRCLE_SIZE);
50
doNothing(PAUSE);
51
}
52
}
53
public
void
startThread()
54
{
55
Thread theThread =
new
Thread(
this
);
56
theThread.start();
57
}
58
public
void
doNothing(
int
milliseconds)
59
{
60
try
61
{
62
Thread.sleep(milliseconds);
63
}
64
catch
(InterruptedException e)
65
{
66
System.out.println("Unexpected interrupt");
67
System.exit(0);
68
}
69
}
70
}
Self-Test Exercises
1. Since
sleep
is a static method, how can it possibly know what thread it needs to
pause?
2. Where was polymorphism used in the program in Display 19.2? (
Hint
: We are
looking for an answer involving the class
Packer
.)
