Open In App
Related Articles

Collections.nCopies() in Java

Improve
Improve
Improve
Like Article
Like
Save Article
Save
Report issue
Report
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, "GeeksforGeeks");
  
        // 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 :
GeeksforGeeks GeeksforGeeks GeeksforGeeks GeeksforGeeks 

The list returned is :
GeeksQuiz GeeksQuiz GeeksQuiz  


Last Updated : 28 Feb, 2018
Like Article
Save Article
Previous
Next
Share your thoughts in the comments
Similar Reads