Prerequisite: ArrayList in Java Given an ArrayList, the task is to get the first and last element of the ArrayList in Java, Examples:
Input: ArrayList = [1, 2, 3, 4] Output: First = 1, Last = 4 Input: ArrayList = [12, 23, 34, 45, 57, 67, 89] Output: First = 12, Last = 89
Approach:
- Get the ArrayList with elements.
- Get the first element of ArrayList with use of get(index) method by passing index = 0.
- Get the last element of ArrayList with use of get(index) method by passing index = size – 1.
Below is the implementation of the above approach:
Java
// Java code to find first and last element// of ArrayListimport java.util.ArrayList;public class GFG { // main method public static void main(String[] args) { // creating an Empty Integer ArrayList ArrayList<Integer> list = new ArrayList<Integer>(5); // using add() to initialize values list.add(1); list.add(2); list.add(3); list.add(4); // printing initial value ArrayList System.out.print("ArrayList: " + list); // find first element int first = list.get(0); // find last element int last = list.get(list.size() - 1); // print first and last element of ArrayList System.out.println("\nFirst : " + first + ", Last : " + last); }} |
Output:
ArrayList: [1, 2, 3, 4] First : 1, Last : 4
Time Complexity: O(1)
Auxiliary Space: O(1)