java date/calendar invalid roll? 1

[birney29]

Hi there,

im doing some calculations with dates/calendars. Sometimes the result of these calculations will be invalid, eg, 31st september. Jave automatically "rolls" the date forward to the 31st of october. Howver, i need it to roll back to to the next vaild date, eg 31st of september. is there any way to tell my code to roll back, rather than forward?

Thanks

Kenneth Birney
User Interface Programmer
Scottish Police

 

[sedj]

Hi, take a look at the below code. It parses a date, and then if Java has bumped the date forward, then it recalculates the date.

		String dd = "32";
		String MM = "03";
		String yy = "04";
		SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yy");
		java.util.Date master = sdf.parse(dd +"/" +MM +"/" +yy, new ParsePosition(0));
		GregorianCalendar gc = new GregorianCalendar();
		gc.setTime(master);

		if (gc.get(Calendar.DAY_OF_MONTH) == Integer.parseInt(dd)) {
			// OK, date parsing was fine
		} else {
			// The day of the month was not correct so Java bumpred the date on,
			// but we don't want to do that, so roll it back a day and re-parse
			int tmp = Integer.parseInt(dd);
			tmp--;
			dd = ""+tmp;
			master = sdf.parse(dd +"/" +MM +"/" +yy, new ParsePosition(0));
			gc = new GregorianCalendar();
			gc.setTime(master);
		}

		java.util.Date parsedDate = gc.getTime();

		System.err.println(parsedDate);