CopyOnWriteArrayList set() method in Java with Examples

The set(E e) method in the class CopyOnWriteArrayList class replaces the element at the specified index with the element provided as a parameter to the method. The method returns the element that has been replaced by the new element.
Syntax:

public E set(int index, E element)

Parameters: The method takes two parameters mentioned below: 

• Index: Contains the position at which the new element is to replace the existing one. It is mandatory to add.
• Element: Contains the new element to be replaced with.

Return Value: The method returns the element that has been replaced.
Exceptions: The method throws IndexOutOfBoundsException occurs when the method has an index that is either less than 0 or greater than the size of the list. 
Below are some programs to illustrate the use of CopyOnWriteArrayList.set() method:
Program 1:

Java

// Program to illustrate the use of set() method

import java.util.concurrent.CopyOnWriteArrayList;

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

        // creating an ArrayList
        CopyOnWriteArrayList<String> arrayList
            = new CopyOnWriteArrayList<String>();

        // Adding elements to the list
        arrayList.add(0, "geeks");
        arrayList.add(1, "for");
        arrayList.add(2, "geeksforgeeks");

        // before invoking the set() method
        System.out.println("CopyOnWriteArrayList: "
                           + arrayList);

        // invoking the set() method
        String returnValue
            = arrayList.set(0, "toodles");

        // printing the returned value
        System.out.println("The value returned "
                           + "on calling set() method:"
                           + returnValue);

        // print CopyOnWriteArrayList
        System.out.println("CopyOnWriteArrayList "
                           + "after calling set():"
                           + arrayList);
    }
}

Program 2:

Java

// Program to illustrate the ArrayIndexOutOfBoundsException

import java.util.concurrent.CopyOnWriteArrayList;

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

        // creating an ArrayList
        CopyOnWriteArrayList<String> arrayList
            = new CopyOnWriteArrayList<String>();

        // Adding elements to the list
        arrayList.add(0, "geeks");
        arrayList.add(1, "for");
        arrayList.add(2, "geeksforgeeks");

        // before invoking the set() method
        System.out.println("CopyOnWriteArrayList: "
                           + arrayList);

        try {

            System.out.println("Trying to add "
                               + "element at index 4 "
                               + "using set() method");

            // invoking the set() method
            String returnValue
                = arrayList.set(4, "toodles");
            // printing the returned value
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}