Is there a stopwatch in Java?

Is there a stopwatch in Java? On google I only find code of stopwatches which don't work - they always return 0 milliseconds.

This code that I found doesn't work but I don't see why.

public class StopWatch {

  private long startTime = 0;
  private long stopTime = 0;
  private boolean running = false;


  public void start() {
    this.startTime = System.currentTimeMillis();
    this.running = true;
  }


  public void stop() {
    this.stopTime = System.currentTimeMillis();
    this.running = false;
  }


  //elaspsed time in milliseconds
  public long getElapsedTime() {
    long elapsed;
    if (running) {
      elapsed = (System.currentTimeMillis() - startTime);
    } else {
      elapsed = (stopTime - startTime);
    }
    return elapsed;
  }


  //elaspsed time in seconds
  public long getElapsedTimeSecs() {
    long elapsed;
    if (running) {
      elapsed = ((System.currentTimeMillis() - startTime) / 1000);
    } else {
      elapsed = ((stopTime - startTime) / 1000);
    }
    return elapsed;
  }
}

Answers


You'll find one in

http://commons.apache.org/lang/

It's called

org.apache.commons.lang.time.StopWatch

But it roughly does the same as yours. If you're in for more precision, use

System.nanoTime()

See also this question here:

Time measuring overhead in Java


Use Guava's Stopwatch class.

An object that measures elapsed time in nanoseconds. It is useful to measure elapsed time using this class instead of direct calls to System.nanoTime() for a few reasons:

  • An alternate time source can be substituted, for testing or performance reasons.
  • As documented by nanoTime, the value returned has no absolute meaning, and can only be interpreted as relative to another timestamp returned by nanoTime at a different time. Stopwatch is a more effective abstraction because it exposes only these relative values, not the absolute ones.
Stopwatch stopwatch = Stopwatch.createStarted();
doSomething();
stopwatch.stop(); // optional

long millis = stopWatch.elapsed(TimeUnit.MILLISECONDS);

log.info("that took: " + stopwatch); // formatted string like "12.3 ms"

Now you can try something like:

Instant starts = Instant.now();
Thread.sleep(10);
Instant ends = Instant.now();
System.out.println(Duration.between(starts, ends));

Output is in ISO 8601.


Spring provides an elegant org.springframework.util.StopWatch Class (spring-core module).

StopWatch stopWatch = new StopWatch();
stopWatch.start();
     // Do something
stopWatch.stop();
     System.out.println(stopWatch.getTotalTimeMillis());

The code doesn't work because elapsed variable in getElapsedTimeSecs() is not a float/double.


Use System.currentTimeMillis() to get the start time and the end time and calculate the difference.

class TimeTest1 {
  public static void main(String[] args) {

    long startTime = System.currentTimeMillis();

    long total = 0;
    for (int i = 0; i < 10000000; i++) {
      total += i;
    }

    long stopTime = System.currentTimeMillis();
    long elapsedTime = stopTime - startTime;
    System.out.println(elapsedTime);
  }
} 

More info at this tutorial


There's no built in Stopwatch utility but as of JSR-310 (Java 8 Time) you can do this simply.

ZonedDateTime now = ZonedDateTime.now();
// Do stuff
long seconds = now.until(ZonedDateTime.now(), ChronoUnit.SECONDS);

I haven't benchmarked this properly but I would guess using Guava's Stopwatch is more effective.


try this

import java.awt.event.*;

import java.awt.*;

import javax.swing.*;

public class millis extends JFrame implements ActionListener, Runnable
    {

     private long startTime;
     private final static java.text.SimpleDateFormat timerFormat = new java.text.SimpleDateFormat("mm : ss.SSS");
     private final JButton startStopButton= new JButton("Start/stop");
     private Thread updater;
     private boolean isRunning= false;
     private final Runnable displayUpdater= new Runnable()
         {
         public void run()
             {
             displayElapsedTime(System.currentTimeMillis() - millis.this.startTime);
         }
     };
     public void actionPerformed(ActionEvent ae)
         {
         if(isRunning)
             {
             long elapsed= System.currentTimeMillis() - startTime;
             isRunning= false;
             try
                 {
                 updater.join();
                 // Wait for updater to finish
             }
             catch(InterruptedException ie) {}
             displayElapsedTime(elapsed);
             // Display the end-result
         }
         else
             {
             startTime= System.currentTimeMillis();
             isRunning= true;
             updater= new Thread(this);
             updater.start();
         }
     }
     private void displayElapsedTime(long elapsedTime)
         {
         startStopButton.setText(timerFormat.format(new java.util.Date(elapsedTime)));
     }
     public void run()
         {
         try
             {
             while(isRunning)
                 {
                 SwingUtilities.invokeAndWait(displayUpdater);
                 Thread.sleep(50);
             }
         }
         catch(java.lang.reflect.InvocationTargetException ite)
             {
             ite.printStackTrace(System.err);
             // Should never happen!
         }
         catch(InterruptedException ie) {}
         // Ignore and return!
     }
     public millis()
         {
         startStopButton.addActionListener(this);
         getContentPane().add(startStopButton);
         setSize(100,50);
         setVisible(true);
     }
     public static void main(String[] arg)
         {
         new Stopwatch().addWindowListener(new WindowAdapter()
             {
             public void windowClosing(WindowEvent e)
                 {
                 System.exit(0);
             }
         });
         millis s=new millis();
         s.run();
     }
}

try this http://introcs.cs.princeton.edu/java/stdlib/Stopwatch.java.html

that's very easy

Stopwatch st = new Stopwatch();
// Do smth. here
double time = st.elapsedTime(); // the result in millis

This class is a part of stdlib.jar


Simple out of the box Stopwatch class:

import java.time.Duration;
import java.time.Instant;

public class StopWatch {

    Instant startTime, endTime;
    Duration duration;
    boolean isRunning = false;

    public void start() {
        if (isRunning) {
            throw new RuntimeException("Stopwatch is already running.");
        }
        this.isRunning = true;
        startTime = Instant.now();
    }

    public Duration stop() {
        this.endTime = Instant.now();
        if (!isRunning) {
            throw new RuntimeException("Stopwatch has not been started yet");
        }
        isRunning = false;
        Duration result = Duration.between(startTime, endTime);
        if (this.duration == null) {
            this.duration = result;
        } else {
            this.duration = duration.plus(result);
        }

        return this.getElapsedTime();
    }

    public Duration getElapsedTime() {
        return this.duration;
    }

    public void reset() {
        if (this.isRunning) {
            this.stop();
        }
        this.duration = null;
    }
}

Usage:

StopWatch sw = new StopWatch();
sw.start();
    // doWork()
sw.stop();
System.out.println( sw.getElapsedTime().toMillis() + "ms");

Try this.

public class StopWatch { 

      private long startTime = 0;
      private long stopTime = 0;

      public StopWatch()
      {
            startTime = System.currentTimeMillis();
      }

      public void start() {
        startTime = System.currentTimeMillis();
      }

      public void stop() {
        stopTime = System.currentTimeMillis();
        System.out.println("StopWatch: " + getElapsedTime() + " milliseconds.");
        System.out.println("StopWatch: " + getElapsedTimeSecs() + " seconds.");
      }

      /**
       * @param process_name
       */
      public void stop(String process_name) {
            stopTime = System.currentTimeMillis();
            System.out.println(process_name + " StopWatch: " + getElapsedTime() + " milliseconds.");
            System.out.println(process_name + " StopWatch: " + getElapsedTimeSecs() + " seconds.");
      }      

      //elaspsed time in milliseconds
      public long getElapsedTime() {
          return stopTime - startTime;
      }

      //elaspsed time in seconds
      public double getElapsedTimeSecs() {
        double elapsed;
          elapsed = ((double)(stopTime - startTime)) / 1000;
        return elapsed;
      }
} 

Usage:

StopWatch watch = new StopWatch();
// do something
watch.stop();

Console:

StopWatch: 143 milliseconds.
StopWatch: 0.143 seconds.

Try this:

/*
 * calculates elapsed time in the form hrs:mins:secs
 */
public class StopWatch
{ 
    private Date startTime;

    public void startTiming()
    {
        startTime = new Date();
    }

    public String stopTiming()
    {
        Date stopTime = new Date();
        long timediff = (stopTime.getTime() - startTime.getTime())/1000L;
        return(DateUtils.formatElapsedTime(timediff));
    }

}

Use:

StopWatch sw = new StopWatch();
...
sw.startTiming();
...
String interval = sw.stopTiming();

use : com.google.common.base.Stopwatch, its simple and easy.

<dependency>
<groupId>com.google.guava</groupId>
<artifactId>guava</artifactId>
<version>23.0</version>
</dependency>

example:

Stopwatch stopwatch = new Stopwatch();
stopwatch.start();

"Do something"

logger.debug("this task took " + stopwatch.stop().elapsedTime(TimeUnit.MILLISECONDS) + " mills");

this task took 112 mills


user1007522, I don't know why your code doesn't work (looks like asfer already commented on that), but I just had the same issue with getting 0 miliseconds from com.google.common.base.Stopwatch.

I was doing

Stopwatch stopwatch = new Stopwatch();
doSomething();
logger.info("test took:" + stopwatch);

Now I'm doing

Stopwatch stopwatch = new Stopwatch().start();
doSomething();
stopwatch.stop();
logger.info("test took:" + stopwatch);

and it works, I get "test took:26.81 s"


You can find a convenient one here:

https://github.com/varra4u/utils4j/blob/master/src/main/java/com/varra/util/StopWatch.java

Usage:

final StopWatch timer = new StopWatch();
System.out.println("Timer: " + timer);
System.out.println("ElapsedTime: " + timer.getElapsedTime());

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