Given an array list, find the first and last elements of it.
Examples:
Input : aList = {10, 30, 20, 14, 2}
Output : First = 10, Last = 2
Input : aList = {10, 30, 40, 50, 60}
Output : First = 10, Last = 60
The last element is at index, size – 1 and the first element is stored at index 0. If we know how to get the size of ArrayList then we can get those two values easily. But remember, that you need to use size() method for ArrayList, not length, length is used to get the length of an array.
Find First and Last in ArrayList:
// java program print first and last element of a Listimport java.util.ArrayList;import java.util.List;public class FindFirstLast { public static void getFirstLat(List<Integer> list) { // Displaying ArrayList elements System.out.println("ArrayList contains: " + list); // Logic to get the last element from ArrayList if (list != null && !list.isEmpty()) { System.out.println("First element is: " + list.get(0)); System.out.println("Last element is: " + list.get(list.size() - 1)); return; } } public static void main(String[] args) { /* Creating ArrayList of Integer and adding elements to it */ List<Integer> al = new ArrayList<Integer>(); al.add(3); al.add(1); al.add(4); al.add(5); al.add(2); getFirstLat(al); }} |
Output:
ArrayList contains: [3, 1, 4, 5, 2] First element is: 3 Last element is: 2
Application : The first element is your lowest and the last element is your highest in case of ascending order and opposite then the first element would be the maximum and last element would be the minimum if List is in descending order.
// java program print Maximum and Minimum Value of a// sorted List, List may be increasing or decreasing orderimport java.util.ArrayList;import java.util.List;public class FindFirstLast { // function find and print Maximum and Minimum value public static void getFirstLat(List<Integer> list) { // Displaying ArrayList elements System.out.println("ArrayList contains: " + list); // Logic to get the last element from ArrayList if (list != null && !list.isEmpty()) { if (list.get(0) < list.get(list.size() - 1)) { // if list in increasing order System.out.println("Minimum Value: " + list.get(0)); System.out.println("Maximum Value: " + list.get(list.size() - 1)); return; } else { // if list in decreasing order System.out.println("Minimum Value: " + list.get(list.size() - 1)); System.out.println("Maximum Value: " + list.get(0)); return; } } } public static void main(String[] args) { /* Creating ArrayList of Integer and adding elements to it */ List<Integer> al = new ArrayList<Integer>(); al.add(5); al.add(4); al.add(3); al.add(2); al.add(1); getFirstLat(al); }} |
Output:
ArrayList contains: [5, 4, 3, 2, 1] Minimum Value: 1 Maximum Value: 5
