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  • How to calculate elapsed / execute time in Java

    How to calculate elapsed / execute time in Java
    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

    http://www.mkyong.com/java/how-do-calculate-elapsed-execute-time-in-java/
    http://www.mkyong.com/tutorials/java-date-time-tutorials/

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  • 原文地址:https://www.cnblogs.com/shy1766IT/p/10116613.html
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