Java Reference
In-Depth Information
Display 19.2
Threaded Version of
FillDemo
(part 2 of 3)
17
private
JPanel box;
18
public static void
main(String[] args)
19 {
20 ThreadedFillDemo gui =
new
ThreadedFillDemo();
21 gui.setVisible(
true
);
22 }
23
public
ThreadedFillDemo()
24 {
25 setSize(WIDTH, HEIGHT);
26 setTitle("Threaded Fill Demo");
27 setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
28 setLayout(
new
BorderLayout());
29 box =
new
JPanel();
30 add(box, "Center");
31 JPanel buttonPanel =
new
JPanel();
32 buttonPanel.setLayout(
new
FlowLayout());
33 JButton startButton =
new
JButton("Start");
34 startButton.addActionListener(
this
);
35 buttonPanel.add(startButton);
36 add(buttonPanel, "South");
37 }
You need a thread object,
even if there are no
instance variables in the
class definition of
Packer
.
38
public void
actionPerformed(ActionEvent e)
39 {
40 Packer packerThread =
new
Packer();
41 packerThread.start();
42 }
start
“
starts
” the thread and calls
run
.
43
private class
Packer
extends
Thread
44 {
45
public void
run()
46 {
47 Graphics g = box.getGraphics();
48
for
(
int
y = 0; y < FILL_HEIGHT; y = y + CIRCLE_SIZE)
49
for
(
int
x = 0; x < FILL_WIDTH; x = x + CIRCLE_SIZE)
50 {
51 g.fillOval(x, y, CIRCLE_SIZE, CIRCLE_SIZE);
52 doNothing(PAUSE);
53 }
54 }
run
is inherited from
Thread
but needs to be
overridden. This definition of
run
is identical
to that of
fill
in Display 19.1.
