Java Date cut off time information

Question

Hi Folks,

I have a Java Date object containing date and time information, e.g. 2008-01-01 13:15:00. I want to write a method that cuts off the time information so I only have the date left, e.g. 2008-01-01 00:00:00.

Do you have a tip? I tried doing something like this

(timestamp / (24 * 60 * 60 * 1000)) * (24 * 60 * 60 * 1000)

but I ran into problems with the timezone...

Thanks for your help!

Marco

Answer 1

The recommended way to do date/time manipulation is to use a Calendar object:

Calendar cal = Calendar.getInstance(); // locale-specific
cal.setTime(dateObject);
cal.set(Calendar.HOUR_OF_DAY, 0);
cal.set(Calendar.MINUTE, 0);
cal.set(Calendar.SECOND, 0);
cal.set(Calendar.MILLISECOND, 0);
long time = cal.getTimeInMillis();

Answer 2

Use the Calendar class's set() method to set the HOUR_OF_DAY, MINUTE, SECOND and MILLISECOND fields to zero.

Answer 3

Date date = new Date();
Calendar cal = Calendar.getInstance();
cal.setTime(date);
cal.set(Calendar.HOUR_OF_DAY, 0);
cal.set(Calendar.MINUTE, 0);
cal.set(Calendar.SECOND, 0);
cal.set(Calendar.MILLISECOND, 0);
date = cal.getTime();

Answer 4

Have you looked at Joda ? It's a much easier and more intuitive way to work with dates and times. For instance you can convert trivially between (say) LocalDateTime and LocalDate objects.

e.g. (to illustrate the API)

LocalDate date = new LocalDateTime(milliseconds).toLocalDate()

Additionally it solves some thread-safety issues with date/time formatters and is to be strongly recommended for working with any date/time issues in Java.

Answer 5

Have you looked at the DateUtils truncate method in Apache Commons Lang?

Date truncatedDate = DateUtils.truncate(new Date(), Calendar.DATE);

will remove the time element.