Is there a stopwatch in Java?

Question

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;
  }
}

Answer 1

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

Answer 2

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"

Answer 3

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.

Answer 4

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());

Answer 5

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

Answer 6

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

Answer 7

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.

Answer 8

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

Answer 9

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");

Answer 10

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.

Answer 11

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

Answer 12

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();
     }
}

Answer 13

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();

Answer 14

Performetrics provides a convenient Stopwatch class, just the way you need. It can measure wall-clock time and more: it also measures CPU time (user time and system time) if you need. It's small, free and you can download from Maven Central. More information and examples can be found here: https://obvj.net/performetrics

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

// Your code

sw.stop();
sw.printStatistics(System.out);

// Sample output:
// +-----------------+----------------------+--------------+
// | Counter         |         Elapsed time | Time unit    |
// +-----------------+----------------------+--------------+
// | Wall clock time |             85605718 | nanoseconds  |
// | CPU time        |             78000500 | nanoseconds  |
// | User time       |             62400400 | nanoseconds  |
// | System time     |             15600100 | nanoseconds  |
// +-----------------+----------------------+--------------+

You can convert the metrics to any time unit (nanoseconds, milliseconds, seconds, etc...)

PS: I am the author of the tool.

Answer 15

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());

Answer 16

Try this.

Java Stopwatch Fully Working Solution

Here you will get a fully working solution.

Just a snippet from the above-linked solution:

You can create a class like below code and use this class' start and stop method before and after the code section, you want to measure the time taken.

public class Stopwatch{
  private long startTime;
  private long stopTime;

  /**
   starting the stop watch.
  */
  public void start(){
        startTime = System.nanoTime();
  }

  /**
   stopping the stop watch.
  */
  public void stop()
  {     stopTime = System.nanoTime(); }

  /**
  elapsed time in nanoseconds.
  */
  public long time(){
        return (stopTime - startTime);
  }

  public String toString(){
      return "elapsed time: " + time() + " nanoseconds.";
  }

}

Thank you.

Answer 17

Try this...

import java.util.concurrent.TimeUnit;
import com.google.common.base.Stopwatch;

public class StopwatchTest {
     
    public static void main(String[] args) throws Exception {
        Stopwatch stopwatch = Stopwatch.createStarted();
        Thread.sleep(1000 * 60);
        stopwatch.stop(); // optional
        long millis = stopwatch.elapsed(TimeUnit.MILLISECONDS);
        System.out.println("Time in milliseconds "+millis);
        System.out.println("that took: " + stopwatch);
    }
}