In Java, you can use the following ways to measure elapsed time in Java.

1. System.nanoTime()

This is the recommended solution to measure elapsed time in Java.

ExecutionTime1.java

package com.mkyong.time;

import java.util.concurrent.TimeUnit;

public class ExecutionTime1 {

    public static void main(String[] args) throws InterruptedException {

		//start
        long lStartTime = System.nanoTime();

		//task
        calculation();

		//end
        long lEndTime = System.nanoTime();

		//time elapsed
        long output = lEndTime - lStartTime;

        System.out.println("Elapsed time in milliseconds: " + output / 1000000);

    }

    private static void calculation() throws InterruptedException {

        //Sleep 2 seconds
        TimeUnit.SECONDS.sleep(2);

    }
}

Output may vary.


2004

2. System.currentTimeMillis()

ExecutionTime2.java

package com.mkyong.time;

import java.util.concurrent.TimeUnit;

public class ExecutionTime2 {

    public static void main(String[] args) throws InterruptedException {

        long lStartTime = System.currentTimeMillis();

        calculation();

        long lEndTime = System.currentTimeMillis();

        long output = lEndTime - lStartTime;

        System.out.println("Elapsed time in milliseconds: " + output);

    }

    private static void calculation() throws InterruptedException {

        //Sleep 2 seconds
        TimeUnit.SECONDS.sleep(2);

    }
}

Output may vary.


2006

3. Instant.now().toEpochMilli()

In Java 8, you can try the new java.time.Instant

ExecutionTime3.java

package com.mkyong.time;

import java.time.Instant;
import java.util.concurrent.TimeUnit;

public class ExecutionTime3 {

    public static void main(String[] args) throws InterruptedException {

        long lStartTime = Instant.now().toEpochMilli();

        calculation();

        long lEndTime = Instant.now().toEpochMilli();

        long output = lEndTime - lStartTime;

        System.out.println("Elapsed time in milliseconds: " + output);

    }

    private static void calculation() throws InterruptedException {

        //Sleep 2 seconds
        TimeUnit.SECONDS.sleep(2);

    }
}

Output may vary.


2006

4. Date().getTime()

ExecutionTime4.java

package com.mkyong.time;

import java.util.Date;
import java.util.concurrent.TimeUnit;

public class ExecutionTime4 {

    public static void main(String[] args) throws InterruptedException {

        long lStartTime = new Date().getTime();

        calculation();

        long lEndTime = new Date().getTime();

        long output = lEndTime - lStartTime;

        System.out.println("Elapsed time in milliseconds: " + output);

    }

    private static void calculation() throws InterruptedException {

        //Sleep 2 seconds
        TimeUnit.SECONDS.sleep(2);

    }
}

Output may vary.


2007

References

  1. Stackoverflow – Is System.nanoTime() completely useless?
  2. Stackoverflow – System.currentTimeMillis vs System.nanoTime
  3. System#nanoTime JavaDoc
  4. Instant#toEpochMilli JavaDoc