The roll(int calndr_field, int amt) method in Calendar class is used to operate on the passed calendar field by adding the passed amount to a specific calendar field without the alteration of large field values.
Note: The positive amount must be added and the negative amount must be subtracted.
Syntax:
public void roll(int calndr_field, int amt)
Parameters: The method takes two parameters:
- calndr_field: This is of Calendar type and refers to the field of the calendar that is to be operated upon.
- amt: This is of the Integer type that is to be added or subtracted depending upon the sign of the value.
Return Value: The method does not return any value.
Below programs illustrate the working of roll() Method of Calendar class:
Example 1:
// Java code to illustrate// isSet() method  import java.util.*;public class Calendar_Demo {    public static void main(String args[])    {          // Creating a calendar        Calendar calndr = Calendar.getInstance();          // Displaying the year        System.out.println("The Current Year"                           + " is: "                           + calndr.get(                                 Calendar.YEAR));          // Decrementing the year        // by 5        calndr.roll(Calendar.YEAR, -5);          // Displaying the result after the operation        System.out.println("The New Year is: "                           + calndr.get(                                 Calendar.YEAR));          // Incrementing the year        // by 2        calndr.roll(Calendar.YEAR, 2);          // Displaying the result after operation        System.out.println("The new year is: "                           + calndr.get(                                 Calendar.YEAR));    }} |
Output:
The Current Year is: 2019 The New Year is: 2014 The new year is: 2016
Example 2:
// Java code to illustrate// isSet() method  import java.util.*;public class Calendar_Demo {    public static void main(String args[])    {          // Creating a calendar        Calendar calndr = Calendar.getInstance();          // Displaying the month        System.out.println("The Current Month"                           + " is: "                           + calndr.get(                                 Calendar.MONTH));          // Incrementing the month        // by 3        calndr.roll(Calendar.MONTH, 3);          // Displaying the result after operation        System.out.println("The New Month is: "                           + calndr.get(                                 Calendar.MONTH));          // Decrementing the month        // by 1        calndr.roll(Calendar.MONTH, -1);          // Displaying the result after operation        System.out.println("The new month is: "                           + calndr.get(                                 Calendar.MONTH));    }} |
Output:
The Current Month is: 2 The New Month is: 5 The new month is: 4
Reference: https://docs.oracle.com/javase/7/docs/api/java/util/Calendar.html#roll(int, %20int)
