The abstract Calendar class provides a set of methods that allows you to convert a time in milliseconds to a number of useful components. Some examples of the type of information that can be provided are year, month, day, hour, minute, and second. It is intended that subclasses of Calendar will provide the specific functionality to interpret time information according to their own rules. This is one aspect of the Java class library that enables you to write programs that can operate in international environments. An example of such a subclass is GregorianCalendar
Calendar provides no public constructors.
| Method | Description |
| abstract void add(int which, int val) | Adds val to the time or date component specified |
| by which. To subtract, add a negative value. which | |
| must be one of the fields defined by Calendar, such | |
| as Calendar.HOUR. | |
| boolean after(Object calendarObj) | Returns true if the invoking Calendar object |
| contains a date that is later than the one specified | |
| by calendarObj. Otherwise, it returns false. | |
| boolean before(Object calendarObj) | Returns true if the invoking Calendar object contains |
| a date that is earlier than the one specified by | |
| calendarObj. Otherwise, it returns false. | |
| final void clear( ) | Zeros all time components in the invoking object. |
| final void clear(int which) | Zeros the time component specified by which in |
| the invoking object. | |
| Object clone( ) | Returns a duplicate of the invoking object. |
| boolean equals(Object calendarObj) | Returns true if the invoking Calendar object |
| contains a date that is equal to the one specified | |
| by calendarObj. Otherwise, it returns false. |
| Method | Description | |||
| int get(int calendarField) | Returns the value of one component of the invoking | |||
| object. The component is indicated by calendarField. | ||||
| Examples of the components that can be requested | ||||
| are Calendar.YEAR, Calendar.MONTH, | ||||
| Calendar.MINUTE, and so forth. | ||||
| static Locale[ ] getAvailableLocales( ) | Returns an array of Locale objects that contains | |||
| the locales for which calendars are available. | ||||
| static Calendar getInstance( ) | Returns a Calendar object for the default locale and | |||
| time zone. | ||||
| static Calendar getInstance(TimeZone tz) | Returns a Calendar object for the time zone | |||
| specified by tz. The default locale is used. | ||||
| static Calendar getInstance(Locale locale) | Returns a Calendar object for the locale specified | |||
| by locale. The default time zone is used. | ||||
| static Calendar getInstance(TimeZone tz, | Returns a Calendar object for the time zone | |||
| Locale locale) | specified by tz and the locale specified by locale. | |||
| final Date getTime( ) | Returns a Date object equivalent to the time of the | |||
| invoking object. | ||||
| TimeZone getTimeZone( ) | Returns the time zone for the invoking object. | |||
| final boolean isSet(int which) | Returns true if the specified time component is set. | |||
| Otherwise, it returns false. | ||||
| void set(int which, int val) | Sets the date or time component specified by which | |||
| to the value specified by val in the invoking object. | ||||
| which must be one of the fields defined by | ||||
| Calendar, such as Calendar.HOUR. | ||||
| final void set(int year, int month, | Sets various date and time components of the | |||
| int dayOfMonth) | invoking object. | |||
| final void set(int year, int month, | Sets various date and time components of the | |||
| int dayOfMonth, int hours, | invoking object. | |||
| int minutes) | ||||
| final void set(int year, int month, | Sets various date and time components of the | |||
| int dayOfMonth, int hours, | invoking object. | |||
| int minutes, int seconds) | ||||
| final void setTime(Date d) | Sets various date and time components of the | |||
| invoking object. This information is obtained from | ||||
| the Date object d. | ||||
| void setTimeZone(TimeZone tz) | Sets the time zone for the invoking object to that | |||
| specified by tz. |
Calendar defines the following int constants, which are used when you get or set components of the calendar:
| ALL_STYLES | FRIDAY | PM | ||
| AM | HOUR | SATURDAY | ||
| AM_PM | HOUR_OF_DAY | SECOND | ||
| APRIL | JANUARY | SEPTEMBER | ||
| AUGUST | JULY | SHORT | ||
| DATE | JUNE | SUNDAY | ||
| DAY_OF_MONTH | LONG | THURSDAY | ||
| DAY_OF_WEEK | MARCH | TUESDAY | ||
| DAY_OF_WEEK_IN_MONTH | MAY | UNDECIMBER | ||
| DAY_OF_YEAR | MILLISECOND | WEDNESDAY | ||
| DECEMBER | MINUTE | WEEK_OF_MONTH | ||
| DST_OFFSET | MONDAY | WEEK_OF_YEAR | ||
| ERA | MONTH | YEAR | ||
| FEBRUARY | NOVEMBER | ZONE_OFFSET | ||
| FIELD_COUNT | OCTOBER |
Demonstrate Calendar
import java.util.Calendar;
class CalendarDemo {
public static void main(String args[]) { String months[] = {
"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
//Create a calendar initialized with the
//current date and time in the default
//locale and timezone.
Calendar calendar = Calendar.getInstance();
//Display current time and date information. System.out.print("Date: "); System.out.print(months[calendar.get(Calendar.MONTH)]); System.out.print(" " + calendar.get(Calendar.DATE) + " "); System.out.println(calendar.get(Calendar.YEAR));
System.out.print("Time: ");
System.out.print(calendar.get(Calendar.HOUR) + ":");
System.out.print(calendar.get(Calendar.MINUTE) + ":");
System.out.println(calendar.get(Calendar.SECOND));
//Set the time and date information and display it. calendar.set(Calendar.HOUR, 10); calendar.set(Calendar.MINUTE, 29); calendar.set(Calendar.SECOND, 22);
System.out.print("Updated time: "); System.out.print(calendar.get(Calendar.HOUR) + ":"); System.out.print(calendar.get(Calendar.MINUTE) + ":"); System.out.println(calendar.get(Calendar.SECOND));
}
}
Output
Date: Jan 1 2007
Time: 11:24:25
Updated time: 10:29:22