Programming Tutorials

Calendar - sample program in Java

By: Lakshmi  

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 several international environments. An example of such a subclass is GregorianCalendar.

Calendar provides no public constructors.

Calendar defines several protected instance variables. areFieldsSet is a boolean that indicates if the time components have been set. fields is an array of ints that holds the components of the time. isSet is a boolean array that indicates if a specific time component has been set. time is a long that holds the current time for this object. isTimeSet is a boolean that indicates if the current time has been set.

The following program demonstrates several Calendar methods:

// 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));
}
}

Sample output is shown here:
Date: Jan 25 1999
Time: 11:24:25
Updated time: 10:29:22