Java Glossary : Date

Java definitions: 0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

You are here : home : Java Glossary : D words : Date.

Date

Java has no standard classes for handling pure dates without times. It does have the following classes:

java.util.Date : for handling date/timestamps presuming GMT. It is the lemon of Java. It is mostly replaced by GregorianCalendar. It is used mainly as if it were a Long wrapper for a date/timestamp.
java.util.GregorianCalender : a date/timestamp and timezone. The timezone is usually ignored.
java.util.SimpleDateFormat : for converting dates to and from human-comprehensible strings.
java.util.TimeZone : represents a timezone. Watch the capital Z. Watch out, Java does not name the timezones in the way Americans are familiar with.

These are among the worst bits of code ever written. You can do quite a bit with

// get time in milliseconds since 1970 Jan 1
long timestamp = System.currentTimeMillis();

If you you use pure longs, you don't have to deal with timezones, leap years, months with variable number of days, regional differences, bulky objects, slow code and all the gotchas in the Date and Calendar classes. SQL can't screw up a long. It surely can a SQLDate. Think hard to keep the bulk of your application dealing with simple longs. Only use Date, Calendar or CalendarFormat when you need to input or output human-readable dates/times.

There are a ton of surprises and bugs awaiting the unwary users of these classes.

BigDate for handling pure dates without times ¤ essay on Dates and Calendars ¤ gotchas for the details ¤ time

home	Canadian Mind Products
	mindprod.com IP:[24.87.56.253]
	Your IP:[80.134.30.163]
	You are visitor number 2768.
	Please send errors, omissions and suggestions
	to improve this page to Roedy Green.
	You can get a fresh copy of this page from:	or possibly from your local J: drive mirror:
	http://mindprod.com/jgloss/date.html	J:\mindprod\jgloss\date.html