计算Java中的日期和时间差

Question

I have three database (SQLServer) fields:

1. startDate (Date)
2. endDate (Date)
3. Duration (text).

I am calculating date and time difference by using java following code.

public static void main(String[] args) {

      DateTimeUtils obj = new DateTimeUtils();
      SimpleDateFormat simpleDateFormat = 
                new SimpleDateFormat("dd/M/yyyy hh:mm:ss");

      try {

        Date date1 = simpleDateFormat.parse("10/10/2013 11:30:10");
        Date date2 = simpleDateFormat.parse("13/10/2013 20:55:55");

        obj.printDifference(date1, date2);

      } catch (ParseException e) {
        e.printStackTrace();
      }

    }

public void printDifference(Date startDate, Date endDate){

        //milliseconds
        long different = endDate.getTime() - startDate.getTime();
        String diff = "";
        System.out.println("startDate : " + startDate);
        System.out.println("endDate : "+ endDate);
        System.out.println("different : " + different);


        diff = String.format("%d:%d", TimeUnit.MILLISECONDS.toHours(different), TimeUnit.MILLISECONDS.toMinutes(different) - TimeUnit.HOURS.toMinutes(TimeUnit.MILLISECONDS.toHours(different)));

And It returns “HH:MM” and updates the Duration field as String in my database. This works great.

Now there will be multiple duration, what I want to do is once I have Duration, I would like to do add up multiple duration and it should return totalDuration:

For Example: In my table # 1 I have,

Id | Duration

1001 | 05:04

1001 | 12:19

1001 | 02:16

Table # 2

Id | totalDuration

1001 | 19:39

My Question is: How do I convert HH:Mm to Date and add multiple records together to get totalDuration. Total duration should be text and return the same format “HH:MM

Answer 1

如果您在表1中确实有开始和结束的日期值，则使用datediff并将这些值求和会容易得多。

Answer 2

If you still have all the values you worked out then just accumulate a long millisecond count as you go and use that.

If not then there are a few ways, the simplest is probably going to be:

String[] split = duration.split(":");
long duration = Long.parseLong(split[0])*60*60*1000 + Long.parseLong(split[1])*60*1000;

You can then loop through adding up all those durations, then at the end convert it back to a String .

Really you should store the millisecond count in your database and then convert it to text to display though.

Answer 3

Question Not Clear

Your question is not clear. (a) Question fails to address issue of time zones. Are these date-times all in UTC/GMT? (b) Your example dates seem to be 3 days apart, yet your code returns only hours and minutes.

Joda-Time

Trying to roll your own date-time calculations usually leads to trouble and frustration. See if a good date-time library can help you, such as Joda-Time or the new java.time.* classes bundled with Java 8.

ISO 8601 Duration

The international standard for date and time, ISO 8601 , defines a way to work with what it calls durations . Historically, the concept has also been called periods. A duration tracks the concept of elapsed time in terms of years, months, days, hours, and minutes.

A value is represented as a string in the format of PnYnMnDTnHnMnS . The 'P' indicates the beginning of a duration (Period) string. A 'T' indicates the time portion. Each number precedes its element designator. For example, "P3Y6M4DT12H30M5S" represents a duration of "three years, six months, four days, twelve hours, thirty minutes, and five seconds".

Joda-Time is ISO 8601 savvy, offering the Period class to represent an ISO duration. A Period can be constructed by passing an ISO duration string. Likewise, the default toString implementation on Period outputs an ISO duration string. You could store that ISO duration string in your database. Joda-Time Period instances can be added together by calling the plus method.

Example Code

Here's example code using Joda-Time 2.3 in Java 7. I sourced the two date-time strings from your question. To demonstrate addition, I add an extra 5 minutes.

Good practice dictates being explicit about time zones rather than rely on defaults. Here I use Paris, choosing so arbitrarily. You may well be using UTC/GMT (no time zone offset), in which case you may pass the pre-defined time zone DateTimeZone.UTC .

// © 2013 Basil Bourque. This source code may be used freely forever by anyone taking full responsibility for doing so.
// import org.joda.time.*;
// import org.joda.time.format.*;

DateTimeZone timeZone_Paris = DateTimeZone.forID( "Europe/Paris" ); // Or for UTC/GMT, use: DateTimeZone.UTC
DateTimeFormatter formatter = DateTimeFormat.forPattern( "dd/MM/yyyy HH:mm:ss" ).withZone( timeZone_Paris );

DateTime start = formatter.parseDateTime( "10/10/2013 11:30:10" );
DateTime stop = formatter.parseDateTime( "13/10/2013 20:55:55" );
Period period = new Period( start, stop );

DateTime now = new DateTime( timeZone_Paris );
Period period2 = new Period( now , now.plusMinutes( 5 ));

Period total = period.plus( period2 );

Dump to console…

System.out.println( "start: " + start.toString() );
System.out.println( "stop: " + stop.toString() );
System.out.println( "period: " + period.toString() );
System.out.println();
System.out.println( "now: " + now.toString() );
System.out.println( "period2: " + period2.toString() );
System.out.println();
System.out.println( "total: " + total.toString() );

When run…

start: 2013-10-10T11:30:10.000+02:00
stop: 2013-10-13T20:55:55.000+02:00
period: P3DT9H25M45S

now: 2013-12-24T01:03:10.029+01:00
period2: PT5M

total: P3DT9H30M45S

Note how the 25M increased to 30M .

Date-Time Strings

Tip: If you control those date-time strings as shown in your example code, your work will be easier if you switched to using the standard ISO 8601 format. For example: 2013-12-21T21:03:48+05:30 or 2013-12-21T21:03:48Z .

Using the "dd/M/yyyy hh:mm:ss" format is ambiguous. No reason to use that rather than the standard format. A bonus: The standard format gives a chronological order when sorting alphabetically.