GregorianCalendar

[nikil shar]

hi all,
have come across this code written by someone else and i dont understand the "gregoriancalendar.get()" part. How can a calender date be deduced from "get(1), get(2), get(5)" ??

           
 GregorianCalendar gregoriancalendar = new GregorianCalendar();
            GregorianCalendar gregoriancalendar1 = new GregorianCalendar(gregoriancalendar.get(1), gregoriancalendar.get(2), gregoriancalendar.get(5));
            GregorianCalendar gregoriancalendar2 = new GregorianCalendar(gregoriancalendar.get(1), gregoriancalendar.get(2), gregoriancalendar.get(5));

I have looked up the API but i dont understand how get(5) can return date/time from default timezone/locale.

ta.

[Christophe Verré]

If you look at the GregorianCalendar API, you'll see that this class inherits a get(int) method from its Calendar parent. The int variable is a Calendar field, declared in static variables in the Calendar class. For example, static int MONTH, static int YEAR. These are static variables, with a value assigned to it. YEAR happens to be 1, MONTH 2, DAY_OF_MONTH 5 (check them here). By retrieving the yar, month and day, you can make a new calendar, the way it's done above. BUT.... never do it like this. Use Calendar.YEAR, Calendar.MONTH and other declared variables, not their values.

[Ireneusz Kordal]

nikil shar wrote:
I have looked up the API but i dont understand how get(5) can return date/time from default timezone/locale.

get(5) doesn't return date/time, it returns day of month.
Look at the source code here: http://www.docjar.com/html/api/java/util/Calendar.java.html

425       /**
  426        * Field number for <code>get</code> and <code>set</code> indicating the
  427        * day of the month. This is a synonym for <code>DAY_OF_MONTH</code>.
  428        * The first day of the month has value 1.
  429        *
  430        * @see #DAY_OF_MONTH
  431        */
  432       public final static int DATE = 5;

constants DATE (value 5) is synonym for DAY_OF_MONTH.

And this invocation:
new GregorianCalendar(gregoriancalendar.get(1), gregoriancalendar.get(2), gregoriancalendar.get(5));

is simply: new GregorianCalendar( year, month, day )

[David Newton]

Don't even need to look in the source; it's in the Javadocs.

[Jesper de Jong]

nikil shar wrote:

           
GregorianCalendar gregoriancalendar = new GregorianCalendar();
GregorianCalendar gregoriancalendar1 = new GregorianCalendar(gregoriancalendar.get(1), gregoriancalendar.get(2), gregoriancalendar.get(5));
GregorianCalendar gregoriancalendar2 = new GregorianCalendar(gregoriancalendar.get(1), gregoriancalendar.get(2), gregoriancalendar.get(5));

This code is ugly for several reasons.

First of all, it's not a good idea to use numbers directly when calling the get() method - it makes it impossible to understand immediately what happens by just looking at the source code. Instead of using numbers, use the constants defined in class Calendar, for example:

int year = calendar.get(Calendar.YEAR);

Second, you should normally not use class GregorianCalendar directly.

// Do not do this unless you have a very specific reason to explicitly use a GregorianCalendar
GregorianCalendar calendar = new GregorianCalendar();

// Instead, do this
Calendar calendar = Calendar.getInstance();