Java Calendar Round To Day

Using java calendar class.

Java calendar round to day. Calendar class in java is an abstract class that provides methods for converting date between a specific instant in time and a set of calendar fields such as month year hour etc. Add hours to current date using calendar add method. And truncate to a multiple of 900000.

Will create a calendar instance representing present date in your current time zone. When rolling on the month or calendar month field other fields like date might conflict and need to be changed. This example shows how to display day of week like monday tuesday etc.

Then use the gettime method to convert this to a java util date reference there are other ways to do this that are similar to this approach but i believe this is the correct way to get an instance of today s date i e a date. And since all time zones in the world change in 15min steps this does not affect rounding to quarters. Subtract days from current date using calendar add method.

Add 7 5minutes or 7 5x60x1000 450000. Extracting the day as a number is trivial now. Remember date is not used to represent dates.

Now what you need is to truncate every field below day hour minute second and millisecond by setting it to 0 you now have a midnight today. For instance rolling the month on the date 01 31 96 will result in 02 29 96. Add or subtract days to current date using java calendar.

When rolling on the hour in day or calendar hour of day field it will roll the hour value in the range between 0 and 23 which is zero based. Calendar c new gregoriancalendar. The day of the week has its own enum dayofweek.