The add(E e) method of CopyOnWriteArrayList inserts the element passed in the parameter to the end of the List or at a specified index in the list. The function returns true on addition of new element to the list.
Syntax:
public boolean add(E e)
or
public void add(int index, E element)
Parameters: The function accepts two types of parameters which are described below:
- index: specifies the index at which the element is to be added. The parameter is not mandatory. If this parameter is not passed, then the addition is done at the end of the list.
- element: specifies the element to be added in the list
Return Value: The function returns true on addition in the list.
Below programs illustrate the above function:
Program 1:
// Java Program to illustrate the CopyOnWriteArrayList// add(element) method in Javaimport java.util.concurrent.CopyOnWriteArrayList;import java.util.*;  public class GFG {    public static void main(String[] args)    {          // create object of CopyOnWriteArrayList        CopyOnWriteArrayList<Integer> ArrLis            = new CopyOnWriteArrayList<Integer>();          // Add elements        ArrLis.add(2);        ArrLis.add(3);        ArrLis.add(4);        ArrLis.add(7);          // print CopyOnWriteArrayList        System.out.println("CopyOnWriteArrayList: " + ArrLis);          System.out.println("On adding 45 it returns "                                      + ArrLis.add(45));    }} |
Output:
CopyOnWriteArrayList: [2, 3, 4, 7] On adding 45 it returns true
Program 2:
// Java Program to illustrate the CopyOnWriteArrayList// add(index, element) method in Javaimport java.util.concurrent.CopyOnWriteArrayList;import java.util.*;  public class GFG {    public static void main(String[] args)    {          // create object of CopyOnWriteArrayList        CopyOnWriteArrayList<Integer> ArrLis            = new CopyOnWriteArrayList<Integer>();          // Add elements at 0th index        ArrLis.add(0, 2);        System.out.println("CopyOnWriteArrayList: " + ArrLis);          // Add elements at 0th index        ArrLis.add(0, 3);        System.out.println("CopyOnWriteArrayList: " + ArrLis);          // Add elements at 1st index        ArrLis.add(1, 4);        System.out.println("CopyOnWriteArrayList: " + ArrLis);          // Add elements at 2nd index        ArrLis.add(2, 7);        System.out.println("CopyOnWriteArrayList: " + ArrLis);    }} |
Output:
CopyOnWriteArrayList: [2] CopyOnWriteArrayList: [3, 2] CopyOnWriteArrayList: [3, 4, 2] CopyOnWriteArrayList: [3, 4, 7, 2]
Reference: https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/CopyOnWriteArrayList.html#add-E-
