The role of Collections.nCopies() is to return an immutable list which contains n copies of given object. This function helps if we want to create a list with n copies of given object. The newly allocated data object is tiny i.e, it contains a single reference to the data object.
Syntax :
public static <T> List<T> nCopies(int number, T object) where, number is the number of copies of object and object represents the element which will appear number times in the returned list. T represents generic type.
Exception : The function throws IllegalArgumentException if value of number is less than 0.
Example :
Java
// Java code to show implementation// of Collections.nCopies()import java.util.*;  class GFG {      // Driver code    public static void main(String[] args)    {          // creating a list where first argument        // represents the number of copies and        // the second argument represents the        // element to be copied for 'number' times        // This will create 4 copies of the objects.        List list = Collections.nCopies(4, "Lazyroar");          // Displaying the list returned        System.out.println("The list returned is :");        Iterator itr = list.iterator();        while (itr.hasNext()) {            System.out.print(itr.next() + " ");        }        System.out.println("\n");          List list1 = Collections.nCopies(3, "GeeksQuiz");              // Displaying the list returned        System.out.println("The list returned is :");        Iterator itr1 = list1.iterator();          while (itr1.hasNext()) {            System.out.print(itr1.next() + " ");        }        System.out.print("\n");    }} |
Output :
The list returned is : Lazyroar Lazyroar Lazyroar Lazyroar The list returned is : GeeksQuiz GeeksQuiz GeeksQuiz
