Java Calendar Class Example | Calendar Class in Java

By Ankit Lathiya Last updated Jan 6, 2020 0

Java calendar class provides methods for converting dates between a specific instant in time and set of calendar fields such as MONTH, YEAR, HOUR, etc. The Calendar class is an abstract class. This class extends Object Class and implements Serializable, Cloneable, and Comparable interfaces. See the following figure.

Methods of Calendar class provide us with converting between a specific instance of time and a set of Fields such as MONTH, YEAR, HOUR, etc.

As it is an Abstract class, we cannot create its instance using the constructor. To initiate and create its subclass, we have Calender.getInstance() static method.

Java Calendar Class Tutorial

As it is the Abstract class, so we cannot use the constructor to create an instance. Instead, we will have to use a static method Calendar.getInstance() to instantiate and implement a sub-class.

Calendar.getInstance(): returns the Calendar instance based on the current time in the default time zone with the default locale.
Calendar.getInstance(TimeZone zone)
Calendar.getInstance(Locale aLocale)
Calendar.getInstance(TimeZone zone, Locale aLocale)

Let’s see the declaration of java.util.Calendar class.

public abstract class Calendar extends Object   
implements Serializable, Cloneable, Comparable<Calendar>

Methods of Calendar Class

#public void add (int field, int amount)

This method helps to add the amount of time-based to specified field according to the calendar rule. This method does not return any value.

// Add.java

import java.util.Calendar;  
public class Add 
{      
 public static void main(String[] args) 
 {  
      // creating a new calendar  
      Calendar c =Calendar.getInstance();  
      // displaying the current date 
      System.out.println("Current date and time: " + c.getTime());        
      // adding 10 years to the current date   
      c.add((Calendar.YEAR), 10);
      // displaying the date after modification 
      System.out.println("Date and time after 10 years: " + c.getTime());  
   }  
}

See the output.

#public boolean after (Object when)

The above method returns true if the method the time of the calendar is after the time represented by the when object if not false is returned.

// After.java

import java.util.*;  
public class After
{  
   public static void main(String[] args) 
   {     
      //  creating calendar objects.  
       Calendar c =Calendar.getInstance();  
      Calendar future = Calendar.getInstance();  
      // displaying  the current date  
      System.out.println("Current date n time:" + c.getTime());  
      // change year in future calendar  
      future.set(Calendar.YEAR, 2016);  
      System.out.println("Year is " + future.get(Calendar.YEAR));  
      // check weather calendar date is after current date  
      Date time = future.getTime();        
      if (!future.after(c)) {  
         System.out.println("Date " + time + " is before current date."); 
      }  
   }
}

See the output.

#public boolean before (Object when)

The above method returns true if the method the time of the calendar is before the time represented by the when object if not false is returned.

// Before.java

import java.util.Calendar;  
import java.util.Date;  
public class Before
{  
   public static void main(String[] args) 
   {  
   // creating calendar objects.  
       Calendar c =  Calendar.getInstance();  
      Calendar past =  Calendar.getInstance();  
      // print the current date  
      System.out.println("Current date: " + c.getTime());  
      // changing the  year in future calendar  
      past.set(Calendar.YEAR, 2017);  
      System.out.println("Year is " + past.get(Calendar.YEAR));  
      // check weather calendar date is after current date  
      Date time = past.getTime();  
           if (past.before(c)) 
		   {  
             System.out.println("Date " + time + " is before current date.");  
           }  
   }  
}

See the following output.

#public final void clear (int field)

The above method sets the given calendar field value and the time value of this calendar undefined.

// Clear.java

import java.util.Calendar;  
public class Clear 
{      
   public static void main(String[] args) 
   {  
      // create a calendar  
       Calendar cal = (Calendar) Calendar.getInstance();  
      // display the current date and time  
      System.out.println("Current Calendar Date: " + cal.getTime());  
      // use clear method to set year as undefined.  
       cal.clear(Calendar.YEAR);  
      // print the result  
     System.out.println("The calendar shows : " + cal.getTime());        
   }  
}

See the output.

public Object clone()

The above method is used to create a copy of the current object.

// Clone.java

import java.util.Calendar;  
public class Clone 
{  
   public static void main(String[] args) 
   {  
      // creating new calendar object 
     Calendar c =(Calendar) Calendar.getInstance(); 
	 
      // displaying date for default value  
      System.out.println("Actual Calendar Object is : " + c.getTime());
	  
      // creating a clone of first calendar object  
     Calendar c1 = (Calendar)c.clone();  
	 
      // displaying the copy  
      System.out.println("Cloned calendar object is : " + c1.getTime());  
   }  
}

See the output.

#public String getCalendarType()

Returns all available calendar types supported by Java run time environment in String.

// CalendarType.java

import java.util.Calendar;  
public class CalendarType 
{  
   public static void main(String[] args) 
   {  
     // creating a calendar class object  
     Calendar c = Calendar.getInstance();  
     //  displaying the calendar type  
     System.out.println("Type of Calendar is " +c.getCalendarType());
   }
}

See the output.

#public int get(int field)

In this method fields of the calendar are passed as a parameter and return the value of the fields.

// Get.java

import java.util.Calendar;  
public class Get
 {  
  public static void main(String[] args) 
  {  
    // creating a calendar   
    Calendar c = Calendar.getInstance(); 
	
    //  DATE field is passed as parameter to get method  
    System.out.println("Day of month is: " +c.get(Calendar.DATE));
	
    //  MONTH field DATE field is passed as parameter to get method  
    System.out.println("Month of year is: " +c.get(Calendar.MONTH));
	
    //  YEAR field DATE field is passed as parameter to get method  
    System.out.println("and year is : " +c.get(Calendar.YEAR));  
    System.out.println("Today is "+c.get(Calendar.DATE) + " Day  of " + c.get(Calendar.MONTH)+ " Month  of  the year " + c.get(Calendar.YEAR) );  
   }
}

See the following example.

#public static Calendar getInstance()

The above method is used with the calendar object to get the instance of the calendar according to the current time zone using by the java runtime environment.

// GetInstance.java

import java.util.Calendar;  
public class GetInstance
 {  
    public static void main(String args[])
	{  
     Calendar c1 = Calendar.getInstance();  
     Calendar c2 = Calendar.getInstance();  
     c2.set(1996, 9 , 23);  
     System.out.println("Calendar 1 :" + c1.getTime());  
     System.out.println("Calendar 2 :" + c2.getTime());  
      if(c1.equals(c2))  
     {  
        System.out.println("Both calendar are equal");  
     }  
      else
	  {  
         System.out.println("Both calendar are not equal");  
      }  
    }  
}

See the output.

Finally, Java Calendar Class Example is over.