Question

Write a test program that prompt the user to enter seven numbers, stores them in an array list and do the following:

1. Displays its elements (numbers) in increasing order by invoking a method with the following header that sorts the array:

public static void sort(ArrayList<Integer>list)

2. Write a method that returns and displays the sum of all numbers (elements) of the ArrayList. Using the following header:

public static double sum(ArrayList<Integer>list)

3. Write a method that removes the duplicate numbers (elements) from the ArrayList and displays the remaining numbers (elements), using the following header:

public static void removeDuplicate(ArrayList<Integer>list)

Answer 1

package com.test;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Scanner;
import java.util.Set;

public class ArrayListOps {

   public static void main(String... ar) {
       ArrayList<Integer> myArrayList = new ArrayList<Integer>();
       Scanner scanner = new Scanner(System.in);
       System.out.println("Please enter 7 numbers of your choice : ");
       for (int i = 0; i < 7; i++) {
           myArrayList.add(scanner.nextInt());
       }
       ArrayListOps.sort(myArrayList);
       ArrayListOps.removeDuplicate(myArrayList);
   }

   public static void sort(ArrayList<Integer> list) {

       //you can use directly list.sort() but if you are looking for custom logic below is the code
      
       for (int i = 0; i < list.size(); ++i) {

           for (int j = i + 1; j < list.size(); ++j) {

               if (list.get(i) > list.get(j)) {

                   int a = list.get(i);
                   list.set(i, list.get(j));
                   list.set(j, a);

               }

           }

       }
       System.out.println("Arranged : "+list);
   }

   public static void removeDuplicate(ArrayList<Integer> list) {
       Set<Integer> tempSetForUniqueValues = new HashSet<Integer>();
       for(Integer temp : list)
       {
           tempSetForUniqueValues.add(temp);
       }
       list.clear();
       list.addAll(tempSetForUniqueValues);
       System.out.println("Removed Duplicates : "+list);
   }

}