我已经编写了一个方法，以易于阅读的形式打印方法执行时间。 例如，要计算100万的阶乘，大约需要9分钟。因此，执行时间打印为:

Execution Time: 9 Minutes, 36 Seconds, 237 MicroSeconds, 806193 NanoSeconds

代码在这里:

public class series
{
    public static void main(String[] args)
    {
        long startTime = System.nanoTime();

        long n = 10_00_000;
        printFactorial(n);

        long endTime = System.nanoTime();
        printExecutionTime(startTime, endTime);

    }

    public static void printExecutionTime(long startTime, long endTime)
    {
        long time_ns = endTime - startTime;
        long time_ms = TimeUnit.NANOSECONDS.toMillis(time_ns);
        long time_sec = TimeUnit.NANOSECONDS.toSeconds(time_ns);
        long time_min = TimeUnit.NANOSECONDS.toMinutes(time_ns);
        long time_hour = TimeUnit.NANOSECONDS.toHours(time_ns);

        System.out.print("\nExecution Time: ");
        if(time_hour > 0)
            System.out.print(time_hour + " Hours, ");
        if(time_min > 0)
            System.out.print(time_min % 60 + " Minutes, ");
        if(time_sec > 0)
            System.out.print(time_sec % 60 + " Seconds, ");
        if(time_ms > 0)
            System.out.print(time_ms % 1E+3 + " MicroSeconds, ");
        if(time_ns > 0)
            System.out.print(time_ns % 1E+6 + " NanoSeconds");
    }
}

把所有可能的方法都集中在一个地方。

Date

Date startDate = Calendar.getInstance().getTime();
long d_StartTime = new Date().getTime();
Thread.sleep(1000 * 4);
Date endDate = Calendar.getInstance().getTime();
long d_endTime = new Date().getTime();
System.out.format("StartDate : %s, EndDate : %s \n", startDate, endDate);
System.out.format("Milli = %s, ( D_Start : %s, D_End : %s ) \n", (d_endTime - d_StartTime),d_StartTime, d_endTime);

System.currentTimeMillis（）

long startTime = System.currentTimeMillis();
Thread.sleep(1000 * 4);
long endTime = System.currentTimeMillis();
long duration = (endTime - startTime);  
System.out.format("Milli = %s, ( S_Start : %s, S_End : %s ) \n", duration, startTime, endTime );
System.out.println("Human-Readable format : "+millisToShortDHMS( duration ) );

人类可读格式

public static String millisToShortDHMS(long duration) {
    String res = "";    // java.util.concurrent.TimeUnit;
    long days       = TimeUnit.MILLISECONDS.toDays(duration);
    long hours      = TimeUnit.MILLISECONDS.toHours(duration) -
                      TimeUnit.DAYS.toHours(TimeUnit.MILLISECONDS.toDays(duration));
    long minutes    = TimeUnit.MILLISECONDS.toMinutes(duration) -
                      TimeUnit.HOURS.toMinutes(TimeUnit.MILLISECONDS.toHours(duration));
    long seconds    = TimeUnit.MILLISECONDS.toSeconds(duration) -
                      TimeUnit.MINUTES.toSeconds(TimeUnit.MILLISECONDS.toMinutes(duration));
    long millis     = TimeUnit.MILLISECONDS.toMillis(duration) - 
                      TimeUnit.SECONDS.toMillis(TimeUnit.MILLISECONDS.toSeconds(duration));

    if (days == 0)      res = String.format("%02d:%02d:%02d.%04d", hours, minutes, seconds, millis);
    else                res = String.format("%dd %02d:%02d:%02d.%04d", days, hours, minutes, seconds, millis);
    return res;
}

Stopwatch的一个对象是测量以纳秒为单位的时间。

com.google.common.base.Stopwatch g_SW = Stopwatch.createUnstarted();
g_SW.start();
Thread.sleep(1000 * 4);
g_SW.stop();
System.out.println("Google StopWatch  : "+g_SW);

Apache Commons LangJAR «StopWatch为计时提供了方便的API。

org.apache.commons.lang3.time.StopWatch sw = new StopWatch();
sw.start();     
Thread.sleep(1000 * 4);     
sw.stop();
System.out.println("Apache StopWatch  : "+ millisToShortDHMS(sw.getTime()) );

乔达时间

public static void jodaTime() throws InterruptedException, ParseException{
    java.text.SimpleDateFormat ms_SDF = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss.SSS");
    String start = ms_SDF.format( new Date() ); // java.util.Date

    Thread.sleep(10000);

    String end = ms_SDF.format( new Date() );       
    System.out.println("Start:"+start+"\t Stop:"+end);

    Date date_1 = ms_SDF.parse(start);
    Date date_2 = ms_SDF.parse(end);        
    Interval interval = new org.joda.time.Interval( date_1.getTime(), date_2.getTime() );
    Period period = interval.toPeriod(); //org.joda.time.Period

    System.out.format("%dY/%dM/%dD, %02d:%02d:%02d.%04d \n", 
        period.getYears(), period.getMonths(), period.getDays(),
        period.getHours(), period.getMinutes(), period.getSeconds(), period.getMillis());
}

Duration对象表示两个Instant对象之间的一段时间。

Instant start = java.time.Instant.now();
    Thread.sleep(1000);
Instant end = java.time.Instant.now();
Duration between = java.time.Duration.between(start, end);
System.out.println( between ); // PT1.001S
System.out.format("%dD, %02d:%02d:%02d.%04d \n", between.toDays(),
        between.toHours(), between.toMinutes(), between.getSeconds(), between.toMillis()); // 0D, 00:00:01.1001 

Spring Framework提供了StopWatch实用程序类来测量Java中的运行时间。

StopWatch sw = new org.springframework.util.StopWatch();
sw.start("Method-1"); // Start a named task
    Thread.sleep(500);
sw.stop();

sw.start("Method-2");
    Thread.sleep(300);
sw.stop();

sw.start("Method-3");
    Thread.sleep(200);
sw.stop();

System.out.println("Total time in milliseconds for all tasks :\n"+sw.getTotalTimeMillis());
System.out.println("Table describing all tasks performed :\n"+sw.prettyPrint());

System.out.format("Time taken by the last task : [%s]:[%d]", 
        sw.getLastTaskName(),sw.getLastTaskTimeMillis());

System.out.println("\n Array of the data for tasks performed « Task Name: Time Taken");
TaskInfo[] listofTasks = sw.getTaskInfo();
for (TaskInfo task : listofTasks) {
    System.out.format("[%s]:[%d]\n", 
            task.getTaskName(), task.getTimeMillis());
}

输出:

Total time in milliseconds for all tasks :
999
Table describing all tasks performed :
StopWatch '': running time (millis) = 999
-----------------------------------------
ms     %     Task name
-----------------------------------------
00500  050%  Method-1
00299  030%  Method-2
00200  020%  Method-3

Time taken by the last task : [Method-3]:[200]
 Array of the data for tasks performed « Task Name: Time Taken
[Method-1]:[500]
[Method-2]:[299]
[Method-3]:[200]

我基本上做的是这种方法的变体，但是考虑到热点编译的工作方式，如果您想要获得准确的结果，您需要抛弃前几个度量，并确保您在真实世界(阅读特定于应用程序的)应用程序中使用该方法。

如果JIT决定编译它，您的数字将会有很大的变化。所以要注意

有几种方法可以做到。我通常会使用这样的方法:

long start = System.currentTimeMillis();
// ... do something ...
long end = System.currentTimeMillis();

或者System.nanoTime();

关于基准测试方面的更多内容，似乎还有这个:http://jetm.void.fm/但从未尝试过。

我们也可以使用Apache公共的StopWatch类来测量时间。

示例代码

org.apache.commons.lang.time.StopWatch sw = new org.apache.commons.lang.time.StopWatch();

System.out.println("getEventFilterTreeData :: Start Time : " + sw.getTime());
sw.start();

// Method execution code

sw.stop();
System.out.println("getEventFilterTreeData :: End Time : " + sw.getTime());

加油，伙计们!没有人提到用番石榴来做这件事(可以说是很棒):

import com.google.common.base.Stopwatch;

Stopwatch timer = Stopwatch.createStarted();
//method invocation
LOG.info("Method took: " + timer.stop());

Stopwatch.toString()很好地为测量选择了时间单位。也就是说，如果值很小，它将输出38ns，如果值很长，它将显示5m 3s

甚至更好的:

Stopwatch timer = Stopwatch.createUnstarted();
for (...) {
   timer.start();
   methodToTrackTimeFor();
   timer.stop();
   methodNotToTrackTimeFor();
}
LOG.info("Method took: " + timer);

注意:谷歌Guava需要Java 1.6+