Decrement a date in Java

Question

I want to get the previous day (24 hours) from the current time.

e.g if current time is Date currentTime = new Date();

2011-04-25 12:15:31:562 GMT

How to determine time i.e

2011-04-24 12:15:31:562 GMT

Answer 1

You can do that using Calendar class:

Calendar cal = Calendar.getInstance();
cal.setTime ( date ); // convert your date to Calendar object
int daysToDecrement = -1;
cal.add(Calendar.DATE, daysToDecrement);
date = cal.getTime(); // again get back your date object

Answer 2

I would suggest you use Joda Time to start with, which is a much nicer API. Then you can use:

DateTime yesterday = new DateTime().minusDays(1);

Note that "this time yesterday" isn't always 24 hours ago though... you need to think about time zones etc. You may want to use LocalDateTime or Instant instead of DateTime.

Answer 3

please checkout this here: Java Date vs Calendar

Calendar cal=Calendar.getInstance();
cal.setTime(date); //not sure if date.getTime() is needed here
cal.add(Calendar.DAY_OF_MONTH, -1);
Date newDate = cal.getTime();

Answer 4

24 hours and 1 day are not the same thing. But you do both using Calendar:

Calendar c = Calendar.getInstance();
c.setTime(new Date());
c.add(Calendar.DATE, -1);
Date d = c.getTime();

If you are going back 24 hours, you would use Calendar.HOUR_OF_DAY