Is there a stopwatch in Java?

Question

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());

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