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The add(E e) method of CopyOnWriteArraySet inserts the element passed in the parameter to the end of the Set or at a specified index in the Set. The function returns true on addition of new element to the Set. Syntax:

public boolean add(E e)

Parameters: The function accepts a single mandatory parameter element which specifies the element to be added in the Set. Return Value: The function returns true on addition in the Set. Below programs illustrate the above function: Program 1:

Java

// Java Program to illustrate the CopyOnWriteArraySet
// add(element) method in Java

import java.util.concurrent.CopyOnWriteArraySet;
import java.util.*;

public class GFG {
    public static void main(String[] args)
    {

        // create object of CopyOnWriteArraySet
        CopyOnWriteArraySet<Integer> ArrSet
            = new CopyOnWriteArraySet<Integer>();

        // Add elements
        ArrSet.add(2);
        ArrSet.add(3);
        ArrSet.add(4);
        ArrSet.add(7);

        // print CopyOnWriteArraySet
        System.out.println("CopyOnWriteArraySet: "
                           + ArrSet);

        // 4 is already present hence cannot add
        System.out.println("On adding 4 it returns "
                           + ArrSet.add(4));

        // print CopyOnWriteArraySet
        System.out.println("Updated CopyOnWriteArraySet: "
                           + ArrSet);
    }
}

Output:

CopyOnWriteArraySet: [2, 3, 4, 7]
On adding 4 it returns false
Updated CopyOnWriteArraySet: [2, 3, 4, 7]

Program 2:

Java

// Java Program to illustrate the CopyOnWriteArraySet
// add(element) method in Java

import java.util.concurrent.CopyOnWriteArraySet;
import java.util.*;

public class GFG {
    public static void main(String[] args)
    {

        // create object of CopyOnWriteArraySet
        CopyOnWriteArraySet<Integer> ArrSet
            = new CopyOnWriteArraySet<Integer>();

        // Add elements
        ArrSet.add(2);
        ArrSet.add(3);
        ArrSet.add(3);
        ArrSet.add(3);

        // print CopyOnWriteArraySet
        System.out.println("CopyOnWriteArraySet: "
                           + ArrSet);

        // 45 is not present hence add
        System.out.println("On adding 45 it returns "
                           + ArrSet.add(45));

        // print CopyOnWriteArraySet
        System.out.println("Updated CopyOnWriteArraySet: "
                           + ArrSet);
    }
}

Output:

CopyOnWriteArraySet: [2, 3]
On adding 45 it returns true
Updated CopyOnWriteArraySet: [2, 3, 45]

Reference: https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/CopyOnWriteArraySet.html#add-E-

CopyOnWriteArraySet add() method in Java

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