Java Reference
In-Depth Information
javax.swing.Timer
+Timer(delay: int, listener:
ActionListener)
+addActionListener(listener:
ActionListener): void
+start(): void
+stop(): void
+setDelay(delay: int): void
Creates a
Timer
object with a specified delay in milliseconds and an
ActionListener
.
Adds an
ActionListener
to the timer.
Starts this timer.
Stops this timer.
Sets a new delay value for this timer.
F
IGURE
16.18
A
Timer
object fires an
ActionEvent
at a fixed rate.
The
Timer
class can be used to control animations. Listing 16.11 gives a program that
displays two messages in separate panels (see Figure 16.19). You can use the mouse button to
control the animation speed for each message. The speed increases when the left mouse
button is clicked and decreases when the right button is clicked.
F
IGURE
16.19
Two messages move in the panels.
L
ISTING
16.11
AnimationDemo.java
1
import
java.awt.*;
2
import
java.awt.event.*;
3
import
javax.swing.*;
4
5
public class
AnimationDemo
extends
JFrame {
6
public
AnimationDemo() {
7
// Create two MovingMessagePanel for displaying two moving messages
8
this
.setLayout(
new
GridLayout(
2
,
1
));
9 add(
new
MovingMessagePanel(
"message 1 moving?"
));
10 add(
new
MovingMessagePanel(
"message 2 moving?"
));
11 }
12
13
/** Main method */
14
public static void
main(String[] args) {
15 AnimationDemo frame =
new
AnimationDemo();
16 frame.setTitle(
"AnimationDemo"
);
17 frame.setLocationRelativeTo(
null
);
// Center the frame
18 frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
19 frame.setSize(
280
,
100
);
20 frame.setVisible(
true
);
21 }
22
23
create message panel
// Inner class: Displaying a moving message
24
static class
MovingMessagePanel
extends
JPanel {
25
private
String message =
"Welcome to Java"
;
26
private int
xCoordinate =
0
;
27
private int
yCoordinate =
20
;
28
private
Timer timer =
new
Timer(
1000
,
new
TimerListener());
create timer
