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Java Collections - Collections.nCopies() Examples

[Last Updated: Nov 8, 2025]

Java Collections Java Java API 

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Class:

java.util.Collections

java.lang.Objectjava.lang.Objectjava.util.Collectionsjava.util.CollectionsLogicBig

Method:

public static <T> List<T> nCopies(int n,
                                  T o)

Returns an immutable list consisting of n elements all pointing to the specified object o.


Examples


package com.logicbig.example.collections;

import java.util.Collections;
import java.util.List;

public class NCopiesExample {

    public static void main(String... args) {
        List<String> list = Collections.nCopies(3, "a");
        System.out.println(list);
    }
}

Output

[a, a, a]




package com.logicbig.example.collections;

import java.util.Collections;
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;

public class NCopiesExample2 {

    public static void main(String... args) {
        AtomicInteger ai = new AtomicInteger();
        List<AtomicInteger> list = Collections.nCopies(3, ai);
        System.out.println(list);

        ai.incrementAndGet();
        System.out.println(list);
    }
}

Output

[0, 0, 0]
[1, 1, 1]

See Also