new Timer(""){{
    // code to time 
}}.timeMe();



public class Timer {

    private final String timerName;
    private long started;

    public Timer(String timerName) {
        this.timerName = timerName;
        this.started = System.currentTimeMillis();
    }

    public void timeMe() {
        System.out.println(
        String.format("Execution of '%s' takes %dms.", 
                timerName, 
                started-System.currentTimeMillis()));
    }

}

nanotime()是一个非常精确的系统实用程序，用于测量执行时间。但是要注意，如果运行在抢占式调度器模式(默认)，这个实用程序实际上测量的是时钟时间，而不是CPU时间。因此，您可能会注意到每次运行的执行时间值是不同的，这取决于系统负载。如果您需要CPU时间，我认为在实时模式下运行您的程序就可以了。您必须使用RT linux。链接:使用Linux进行实时编程

您可以使用Perf4j。非常酷的实用工具。用法简单

String watchTag = "target.SomeMethod";
StopWatch stopWatch = new LoggingStopWatch(watchTag);
Result result = null; // Result is a type of a return value of a method
try {
    result = target.SomeMethod();
    stopWatch.stop(watchTag + ".success");
} catch (Exception e) {
    stopWatch.stop(watchTag + ".fail", "Exception was " + e);
    throw e; 
}

更多信息可以在开发者指南中找到

编辑:项目似乎已死

非常好的代码。

http://www.rgagnon.com/javadetails/java-0585.html

import java.util.concurrent.TimeUnit;

long startTime = System.currentTimeMillis();
........
........
........
long finishTime = System.currentTimeMillis();

String diff = millisToShortDHMS(finishTime - startTime);


  /**
   * converts time (in milliseconds) to human-readable format
   *  "<dd:>hh:mm:ss"
   */
  public static String millisToShortDHMS(long duration) {
    String res = "";
    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));
    if (days == 0) {
      res = String.format("%02d:%02d:%02d", hours, minutes, seconds);
    }
    else {
      res = String.format("%dd%02d:%02d:%02d", days, hours, minutes, seconds);
    }
    return res;
  }

使用AOP/AspectJ和来自jcabi-aspects的@Loggable注释，你可以简单而紧凑地完成:

@Loggable(Loggable.DEBUG)
public String getSomeResult() {
  // return some value
}

对该方法的每个调用都将发送到SLF4J日志记录工具，具有DEBUG日志记录级别。每个日志消息都将包括执行时间。

这是一个简单的类用于简单的函数计时。下面有一个例子。

public class Stopwatch {
    static long startTime;
    static long splitTime;
    static long endTime;

    public Stopwatch() {
        start();
    }

    public void start() {
        startTime = System.currentTimeMillis();
        splitTime = System.currentTimeMillis();
        endTime = System.currentTimeMillis();
    }

    public void split() {
        split("");
    }

    public void split(String tag) {
        endTime = System.currentTimeMillis();
        System.out.println("Split time for [" + tag + "]: " + (endTime - splitTime) + " ms");
        splitTime = endTime;
    }

    public void end() {
        end("");
    }
    public void end(String tag) {
        endTime = System.currentTimeMillis();
        System.out.println("Final time for [" + tag + "]: " + (endTime - startTime) + " ms");
    }
}

使用示例:

public static Schedule getSchedule(Activity activity_context) {
        String scheduleJson = null;
        Schedule schedule = null;
/*->*/  Stopwatch stopwatch = new Stopwatch();

        InputStream scheduleJsonInputStream = activity_context.getResources().openRawResource(R.raw.skating_times);
/*->*/  stopwatch.split("open raw resource");

        scheduleJson = FileToString.convertStreamToString(scheduleJsonInputStream);
/*->*/  stopwatch.split("file to string");

        schedule = new Gson().fromJson(scheduleJson, Schedule.class);
/*->*/  stopwatch.split("parse Json");
/*->*/  stopwatch.end("Method getSchedule"); 
    return schedule;
}

控制台输出示例:

Split time for [file to string]: 672 ms
Split time for [parse Json]: 893 ms
Final time for [get Schedule]: 1565 ms