Taken from the docs here: Adds or subtracts the specified amount of time to the given calendar field, based on the calendar’s rules. For example, to subtract 5 days from the current time of the calendar, you can achieve it by calling: Calendar calendar = Calendar.getInstance(); // this would default to now calendar.add(Calendar.DAY_OF_MONTH, -5).
Calendar cal = Calendar.getInstance(); SimpleDateFormat sdf = new SimpleDateFormat(“EEE MMM dd HH:mm:ss z yyyy”, Locale.ENGLISH); cal.setTime(sdf.parse(“Mon Mar 14 16:02:37 GMT 2011”));// all done note: set Locale according to your environment/requirement See Also Javadoc
Java 8 and later With Java 8’s date time API change, Use LocalDate LocalDate date = LocalDate.now().minusDays(300); Similarly you can have LocalDate date = someLocalDateInstance.minusDays(300); Refer to https://stackoverflow.com/a/23885950/260990 for translation between java.util.Date <–> java.time.LocalDateTime Date in = new Date(); LocalDateTime ldt = LocalDateTime.ofInstant(in.toInstant(), ZoneId.systemDefault()); Date out = Date.from(ldt.atZone(ZoneId.systemDefault()).toInstant()); Java 7 and earlier Use Calendar‘s add() … Read more
Here’s your method: public static Calendar toCalendar(Date date){ Calendar cal = Calendar.getInstance(); cal.setTime(date); return cal; } Everything else you are doing is both wrong and unnecessary. BTW, Java Naming conventions suggest that method names start with a lower case letter, so it should be: dateToCalendar or toCalendar (as shown). OK, let’s milk your code, shall … Read more
Use the “MMMM” custom format specifier: DateTime.Now.ToString(“MMMM”);
A Java Date is a container for the number of milliseconds since January 1, 1970, 00:00:00 GMT. When you use something like System.out.println(date), Java uses Date.toString() to print the contents. The only way to change it is to override Date and provide your own implementation of Date.toString(). Now before you fire up your IDE and … Read more
I would use a ‘link’ concept for all future recurring events. They are dynamically displayed in the calendar and link back to a single reference object. When events have taken place the link is broken and the event becomes a standalone instance. If you attempt to edit a recurring event then prompt to change all … Read more
System.currentTimeMillis() is obviously the most efficient since it does not even create an object, but new Date() is really just a thin wrapper about a long, so it is not far behind. Calendar, on the other hand, is relatively slow and very complex, since it has to deal with the considerably complexity and all the … Read more
It’s just part of the horrendous mess which is the Java date/time API. Listing what’s wrong with it would take a very long time (and I’m sure I don’t know half of the problems). Admittedly working with dates and times is tricky, but aaargh anyway. Do yourself a favour and use Joda Time instead, or … Read more
Storing “Simple” Repeating Patterns For my PHP/MySQL based calendar, I wanted to store repeating/recurring event information as efficiently as possibly. I didn’t want to have a large number of rows, and I wanted to easily lookup all events that would take place on a specific date. The method below is great at storing repeating information … Read more