Collections.nCopies in Java
February 05, 2022
Find the Java doc of Collections.nCopies
method.
static <T> List<T> nCopies(int n, T o)
nCopies
method returns an immutable list consisting of n copies of the specified object.
n is the number of elements in the returned list.
o is the element that repeatedly added in the list.
Example-1
CollectionsNCopies1.javapackage com.concretepage; import java.util.Collections; import java.util.List; public class CollectionsNCopies1 { public static void main(String[] args) { List<String> list1 = Collections.nCopies(5, "Ram"); System.out.println(list1); List<Integer> list2 = Collections.nCopies(10, 5); System.out.println(list2); } }
[Ram, Ram, Ram, Ram, Ram] [5, 5, 5, 5, 5, 5, 5, 5, 5, 5]
Example-2
package com.concretepage; import java.util.Collections; import java.util.List; public class CollectionsNCopies2 { public static void main(String[] args) { Person p1 = new Person("A"); List<Person> list = Collections.nCopies(20, p1); System.out.println(list.size()); // Output 20 } } class Person { private String name; public Person(String name) { this.name = name; } public String getName() { return name; } public void setName(String name) { this.name = name; } }