ArrayList.add() method is used to add an element at particular index in Java ArrayList.
Syntax:
public void add(int index, Object element) ;
Parameters:
- index -position at which the element has to be inserted. The index is zero-based.
- element – the element to be inserted at the specified position.
Exception: throws IndexOutOfBoundsException which occurs when the index is trying to be accessed which isn’t there in the allocated memory block. In java, this exception is thrown when a negative index is accessed or an index of memory space. Here particularly when an index greater than the size of ArrayList is trying to be fetched or the insertion of an element at an index greater than size() of ArrayList is fetched.
Example:
For a list of string
list=[A,B,C]
list.add(1,”D”);
list.add(2,”E”);
list=[A,D,E,B,C]
For a list of integers
LIST=[1,2,3]
list.add(2,4);
list=[1,2,4,3]
Implementation:
Java
// Adding an Element at Particular// Index in Java ArrayListimport java.io.*;import java.util.ArrayList;class GFG { // Main driver method public static void main(String[] args) { // Creating an ArrayList ArrayList<String> list = new ArrayList<>(); // Adding elements to ArrayList // using add method for String ArrayList list.add("A"); list.add("B"); list.add("C"); /* Index is zero based */ // 3 gets added to the 1st position list.add(1, "D"); // 4 gets added to the 2nd(position) list.add(2, "E"); // Displaying elements in ArrayList System.out.println(list); }} |
[A, D, E, B, C]
Time Complexity: O(n)
Auxiliary Space: O(1)
As constant extra space is used.
