Question

Write a method called removeLast that removes and returns the last value from a list of integers. For example, if a variable called list stores [8, 17, 42, 3, 8], a call of list.removeLast(); should return 8 and change the list’s state to [8, 17, 42, 3]. The next call would return 3 and remove 3 from the list, and so on. If the list is empty, throw a NoSuchElementException.

The program needs to be in Java. Please also create a main Method to test the code.

Answer 1

CODE IN JAVA:

ListDemo.java file:

import java.util.*;

public class ListDemo {
   public static int removeLast(ArrayList<Integer> arr) {
       int n = arr.size();
       if (n == 0)
           throw new NoSuchElementException();
       else {
           int result = arr.get(n - 1);
           arr.remove(n - 1);
           return result;
       }

   }

   public static void displayArr(ArrayList<Integer> arr) {
       if (arr.size() == 0) {
           System.out.println("Your array is empty");
           return;
       }
       for (int val : arr)
           System.out.print(val + " ");
       System.out.println("");
   }

   public static void main(String[] args) {
       try {
           ArrayList<Integer> arr = new ArrayList<Integer>();
           arr.add(8);
           arr.add(17);
           arr.add(42);
           arr.add(3);
           arr.add(8);
           System.out.println("Now your array list is : ");
           displayArr(arr);
           removeLast(arr);
           System.out.println("After calling removeLast method your array list is : ");
           displayArr(arr);
           removeLast(arr);
           System.out.println("After calling removeLast method your array list is : ");
           displayArr(arr);
           removeLast(arr);
           System.out.println("After calling removeLast method your array list is : ");
           displayArr(arr);
           removeLast(arr);
           System.out.println("After calling removeLast method your array list is : ");
           displayArr(arr);
           removeLast(arr);
           System.out.println("After calling removeLast method your array list is : ");
           displayArr(arr);
           System.out.println("After calling removeLast method your array list is : ");
           removeLast(arr);
           displayArr(arr);
       } catch (NoSuchElementException e) {
           System.out.println(e);
       }

   }

}

OUTPUT: