Conceptually, the idea is, you want to keep track of the "total running" of the stop watch, this is, all the total duration it has been active.
There's a number of ways you might achieve this, one might be to simply keep a running total which is only updated when the stop watch is stopped or paused. The "duration" of the stop watch is then a sum of the "current duration" of the "current" cycle and the "total previous" duration
Something like...
public class StopWatch {
private LocalDateTime startTime;
private Duration totalRunTime = Duration.ZERO;
public void start() {
startTime = LocalDateTime.now();
}
public void stop() {
Duration runTime = Duration.between(startTime, LocalDateTime.now());
totalRunTime = totalRunTime.plus(runTime);
startTime = null;
}
public void pause() {
stop();
}
public void resume() {
start();
}
public void reset() {
stop();
totalRunTime = Duration.ZERO;
}
public boolean isRunning() {
return startTime != null;
}
public Duration getDuration() {
Duration currentDuration = Duration.ZERO;
currentDuration = currentDuration.plus(totalRunTime);
if (isRunning()) {
Duration runTime = Duration.between(startTime, LocalDateTime.now());
currentDuration = currentDuration.plus(runTime);
}
return currentDuration;
}
}
Okay, so start and stop are essentially the same as pause and resume, but you get the point.
And, a runnable example...
Now, this example runs a Swing Timer constantly, but the StopWatch can paused and resumed at any time, the point is to demonstrate that the StopWatch is actually working correctly ;)
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.time.Duration;
import java.time.LocalDateTime;
import javax.swing.JButton;
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 Test {
public static void main(String[] args) throws InterruptedException {
new Test();
}
public Test() {
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 JLabel label;
private JButton btn;
private StopWatch stopWatch = new StopWatch();
private Timer timer;
public TestPane() {
label = new JLabel("...");
btn = new JButton("Start");
setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridwidth = GridBagConstraints.REMAINDER;
add(label, gbc);
add(btn, gbc);
timer = new Timer(500, new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
label.setText(Long.toString(stopWatch.getDuration().getSeconds()));
}
});
timer.start();
btn.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
if (stopWatch.isRunning()) {
stopWatch.pause();
btn.setText("Start");
} else {
stopWatch.resume();
btn.setText("Pause");
}
}
});
}
@Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.dispose();
}
}
public class StopWatch {
private LocalDateTime startTime;
private Duration totalRunTime = Duration.ZERO;
public void start() {
startTime = LocalDateTime.now();
}
public void stop() {
Duration runTime = Duration.between(startTime, LocalDateTime.now());
totalRunTime = totalRunTime.plus(runTime);
startTime = null;
}
public void pause() {
stop();
}
public void resume() {
start();
}
public void reset() {
stop();
totalRunTime = Duration.ZERO;
}
public boolean isRunning() {
return startTime != null;
}
public Duration getDuration() {
Duration currentDuration = Duration.ZERO;
currentDuration = currentDuration.plus(totalRunTime);
if (isRunning()) {
Duration runTime = Duration.between(startTime, LocalDateTime.now());
currentDuration = currentDuration.plus(runTime);
}
return currentDuration;
}
}
}
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