Find total hours between two Dates

Question

I have two Date objects and I need to get the time difference so I can determine the total hours between them. They happen to be from the same day. The result I would like w

Answer 1

So the getTime() method, I presume, returns an integer.

In which case, the left set of parentheses has type int, right?

and

(60*60*1000)

is also an int.

Which means you get long diff = ((int)/(int)) so the integer division is done BEFORE you cast stuff to long. And hence you lose your minutes.

Try casting them BEFORE you divide.

Answer 2

Here's a pure Java 8+ solution that does not involve Joda or mathematical operations

import java.time.*;
import java.time.temporal.*;

// given two java.util.Dates
Date startDate ...
Date endDate ...

// convert them to ZonedDateTime instances
ZonedDateTime start = ZonedDateTime.ofInstant(startDate.toInstant(), ZoneId.systemDefault());
ZonedDateTime end = ZonedDateTime.ofInstant(endDate.toInstant(), ZoneId.systemDefault());

// get the total duration of minutes between them
Duration total = Duration.ofMinutes(ChronoUnit.MINUTES.between(start, end));

// use the duration to determine the hours and minutes values
long hours = total.toHours();
long minutes = total.minusHours(hours).toMinutes();

Answer 3

Please follow Somaiah's suggestion in a comment, use Hours instead:

Hours hours = Hours.hoursBetween(startTime, endTime);

The call to getHours() will only return the hour section of the time difference and ignore all year, month differences so it would not be correct in some cases.

If you use Period.toStandardHours() to try to convert the time difference into hours the calculation will throw an exception if the time difference between the two dates includes difference in either year or month, since the length of month is unknown.

Answer 4

private void getHours(Date d1, Date d2){
long diff = d2.getTime() - d1.getTime();

  long diffSeconds = diff / 1000 % 60;
        long diffMinutes = diff / (60 * 1000) % 60;
  long diffDays = diff / (24 * 60 * 60 * 1000);
        long diffHours = diff / (60 * 60 * 1000) % 24;

        System.out.print(diffDays + " days, ");
        System.out.print(diffHours + " hours, ");
        System.out.print(diffMinutes + " minutes, ");
        System.out.print(diffSeconds + " seconds.\n");

}`

//Displays: /* 1 days, 1 hours, 1 minutes, 50 seconds. */

Answer 5

Here's how it works with Joda time:

DateTime startTime, endTime;
Period p = new Period(startTime, endTime);
int hours = p.getHours();
int minutes = p.getMinutes();

You could format with Joda's formatters, e.g., PeriodFormat, but I'd suggest using Java's. See this question for more details.

Answer 6

This should work.

long secs = (this.endDate.getTime() - this.startDate.getTime()) / 1000;
int hours = secs / 3600;    
secs = secs % 3600;
int mins = secs / 60;
secs = secs % 60;