The time between ticks (the time when actionPerfomed
is called) is variable, it only guarantees that it will be at least n
milliseconds
Instead of relying on some counter, which could become unreliable over time, you should try and calculate the difference between the time the Timer
was started and the current time, for example…
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.text.SimpleDateFormat;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class CountDown {
public static void main(String[] args) {
new CountDown();
}
public CountDown() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private Timer timer;
private long startTime = -1;
private long duration = 5000;
private JLabel label;
public TestPane() {
setLayout(new GridBagLayout());
timer = new Timer(10, new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
if (startTime < 0) {
startTime = System.currentTimeMillis();
}
long now = System.currentTimeMillis();
long clockTime = now - startTime;
if (clockTime >= duration) {
clockTime = duration;
timer.stop();
}
SimpleDateFormat df = new SimpleDateFormat("mm:ss:SSS");
label.setText(df.format(duration - clockTime));
}
});
timer.setInitialDelay(0);
addMouseListener(new MouseAdapter() {
@Override
public void mouseClicked(MouseEvent e) {
if (!timer.isRunning()) {
startTime = -1;
timer.start();
}
}
});
label = new JLabel("...");
add(label);
}
@Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
}
}