Java.util.Collections.rotate() Method in Java with Examples
Last Updated : 07 Dec, 2018
java.util.Collections.rotate() method is present in java.util.Collections class. It is used to rotate the elements present in the specified list of Collection by a given distance.
Syntax: public static void rotate(List< type > list, int distance) Parameters : list - the list to be rotated. distance - the distance to rotate the list. type - Type of list to be rotated. Examples of types are Integer, String, etc. Returns : NA Throws: UnsupportedOperationException - if the specified list or its list-iterator does not support the set operation.
There are no constraints on distance value. It may be zero, negative, or greater than list.size(). After calling this method, the element at index i will be the element previously at index (i - distance) mod list.size(), for all values of i between 0 and list.size()-1, inclusive.
Java // Java program to demonstrate working of // java.utils.Collections.rotate() import java.util.*; public class RotateDemo { public static void main(String[] args) { // Let us create a list of strings List<String> mylist = new ArrayList<String>(); mylist.add("practice"); mylist.add("code"); mylist.add("quiz"); mylist.add("geeksforgeeks"); System.out.println("Original List : " + mylist); // Here we are using rotate() method // to rotate the element by distance 2 Collections.rotate(mylist, 2); System.out.println("Rotated List: " + mylist); } } Output:
Original List : [practice, code, quiz, geeksforgeeks] Rotated List: [quiz, geeksforgeeks, practice, code]
How to quickly rotate an array in Java using rotate()?
Arrays class in Java doesn’t have rotate method. We can use Collections.rotate() to quickly rotate an array also.
Java // Java program to demonstrate rotation of array // with Collections.rotate() import java.util.*; public class RotateDemo { public static void main(String[] args) { // Let us create an array of integers Integer arr[] = {10, 20, 30, 40, 50}; System.out.println("Original Array : " + Arrays.toString(arr)); // Please refer below post for details of asList() // https://www.geeksforgeeks.org/array-class-in-java/ // rotating an array by distance 2 Collections.rotate(Arrays.asList(arr), 2); System.out.println("Modified Array : " + Arrays.toString(arr)); } } Output:
Original Array : [10, 20, 30, 40, 50] Modified Array : [40, 50, 10, 20, 30]
Similar Reads
Collections swap() method in Java with Examples The swap() method of java.util.Collections class is used to swap the elements at the specified positions in the specified list. If the specified positions are equal, invoking this method leaves the list unchanged. Syntax: public static void swap(List list, int i, int j) Parameters: This method takes
2 min read
Collections.reverse() Method in Java with Examples The reverse() method of the Collections class, as the name suggests, is used to reverse the order of elements in a list. Note: It does not sort the elements, it simply reverses their current order.This class is present in java.util package so the syntax is as follows:import java.util.Collections;Col
3 min read
Collections list() method in Java with Examples The list() method of java.util.Collections class is used to return an array list containing the elements returned by the specified enumeration in the order they are returned by the enumeration. This method provides interoperability between legacy APIs that return enumerations and new APIs that requi
2 min read
Collectors toList() method in Java with Examples The toList() method of Collectors Class is a static (class) method. It returns a Collector Interface that gathers the input data onto a new list. This method never guarantees type, mutability, serializability, or thread-safety of the returned list but for more control toCollection(Supplier) method c
2 min read
Collections synchronizedList() method in Java with Examples The synchronizedList() method of java.util.Collections class is used to return a synchronized (thread-safe) list backed by the specified list. In order to guarantee serial access, it is critical that all access to the backing list is accomplished through the returned list. Syntax: public static <
2 min read