How to calculate the running time of my program

Question

I wrote a program and now I want to calculate the total running time of my program from start to end   How can I do this

User · Answer

You need to get the time when the application starts, and compare that to the time when the application ends.

Wen the app starts:

Calendar calendar = Calendar.getInstance();

// Get start time (this needs to be a global variable).
Date startDate = calendar.getTime();

When the application ends

Calendar calendar = Calendar.getInstance();

// Get start time (this needs to be a global variable).
Date endDate = calendar.getTime();

To get the difference (in millseconds), do this:

long sumDate = endDate.getTime() - startDate.getTime();

User · Answer

Use System nanoTime to get the current time   long startTime   System nanoTime         your program     long endTime     System nanoTime    long totalTime   endTime - startTime  System out println totalTime     The above code prints the running time of the program in nanoseconds

User · Answer

Use System currentTimeMillis   or System nanoTime   if you want even more precise reading  Usually  milliseconds is precise enough if you need to output the value to the user  Moreover  System nanoTime   may return negative values  thus it may be possible that  if you re using that method  the return value is not correct   A general and wide use would be to use milliseconds    long start   System currentTimeMillis            long end   System currentTimeMillis     NumberFormat formatter   new DecimalFormat   0 00000    System out print  Execution time is     formatter format  end - start    1000d      seconds      Note that nanoseconds are usually used to calculate very short and precise program executions  such as unit testing and benchmarking  Thus  for overall program execution  milliseconds are preferable

User · Answer

At the beginning of your main method  add this line of code    final long startTime   System nanoTime      And then  at the last line of your main method  you can add    final long duration   System nanoTime   - startTime    duration now contains the time in nanoseconds that your program ran  You can for example print this value like this   System out println duration     If you want to show duration time in seconds  you must divide the value by 1 000 000 000  Or if you want a Date object  Date myTime   new Date duration   1000   You can then access the various methods of Date to print number of minutes  hours  etc

User · Answer

Beside the well-known  and already mentioned  System currentTimeMillis   and System nanoTime   there is also a neat library called perf4j which might be useful too  depending on your purpose of course

User · Answer

The general approach to this is to    Get the time at the start of your benchmark  say at the start of main    Run your code  Get the time at the end of your benchmark  say at the end of main    Subtract the start time from the end time and convert into appropriate units    A hint  look at System nanoTime   or System currentTimeMillis

[java] How to calculate the running time of my program?

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