Time difference in Java [duplicate]

Answer 1

Alternatively, if you don't want to use JodaTime, it's pretty simple to compute the hours, minutes, and seconds from a duration in milliseconds:

public static void main(String[] args) throws ParseException {
  SimpleDateFormat sdf = new SimpleDateFormat("HH:mm:ss");
  Date start = sdf.parse("00:44:16");
  Date end = sdf.parse("04:02:39");
  long durationMs = end.getTime() - start.getTime();

  final int oneHourMs = 3600000;
  final int oneMinuteMs = 60000;
  final int oneSecondMs = 1000;

  long hours = durationMs / oneHourMs;
  long minutes = (durationMs % oneHourMs) / oneMinuteMs;
  long seconds = (durationMs % oneMinuteMs) / oneSecondMs;

  System.out.format("%02d:%02d:%02d", hours, minutes, seconds); 
  // outputs: 03:18:23
}

Answer 2

Problems:

• You are cramming a time-of-day value into a date-time object.
• You are using notoriously troublesome old date-time classes, now legacy, supplanted by the java.time classes.

The LocalTime class represents a time-of-day value without a date and without a time zone.

LocalTime start = LocalTime.parse( "00:44:16" ); 
LocalTime stop = LocalTime.parse( "04:02:39" );

The Duration represents a span of time not attached to the timeline.

Duration duration = Duration.between ( start , stop );

Answer 3

Because that's not how you get a duration. Change your code to this:

package com.sandbox;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

public class Sandbox {

    public static void main(String[] args) {
        SimpleDateFormat sdf = new SimpleDateFormat("HH:mm:ss");
        try {
            Date start = sdf.parse("00:44:16");
            Date end = sdf.parse("04:02:39");
            long duration = end.getTime() - start.getTime();
            Calendar cal = Calendar.getInstance();
            cal.setTimeInMillis(duration);
            System.out.println(new SimpleDateFormat("yyyy MM dd HH:mm:ss").format(cal.getTime()));
        } catch (ParseException e) {
            e.printStackTrace();
        }
    }
}

You'll see it prints out 1969 12 31 19:18:23. That's a date not a duration. Since you're skipping the date components when you print out your answer, it appears like it's printing out a duration, but it's really not.

To be frank, I don't know how to do this in java. I just use the JodaTime library. There's a class called Duration that makes this easy. Here's a SO question that shows how to use it to print out the results any way you want: "pretty print" duration in java