-1

I tried to add an Array, but i am not sure if it is necessary here.

import java.util.Scanner;
import java.util.ArrayList;

class Main {
  public static void main(String[] args) {
    
        while (true){

            Scanner user= new Scanner(System.in);

            ArrayList<Integer> userfeed = new ArrayList<>();

            System.out.println("Enter a number:");

            int num = Integer.valueOf(user.nextLine());

            userfeed.add(num);
            
            if (num == -1){

            int number1 = 0;
            int number2 = userfeed.get(num);
            int Sum = sum(number1, number2);
            System.out.println(Sum);

            break;

            }

         }
        
  }

    public static int sum(int numero1, int numero2){

        int Numerosum = numero1 + numero2;

        return Numerosum;
        
    }
}

The output should look like for example:

Enter a number:
15
Enter a number:
13
Enter a number:
14
Enter a number:
36
Enter a number::
-1
78

I can't quite figure out how to add up the inputted numbers, if that is possible. Please bare with me, because I am quite a beginner.

BaselE
  • 49
  • 6

2 Answers2

0

You can use a do-while loop:

import java.util.Scanner;
import java.util.ArrayList;

public class Main {
  public static void main(String[] args) {
      Scanner user= new Scanner(System.in);
      ArrayList<Integer> userfeed = new ArrayList<>();

      int num=0;
        
      do {
          System.out.println("Enter a number:");
          num = Integer.valueOf(user.nextLine());
          userfeed.add(num);    
      }while (num != -1);
      
      //calculating the sum of the array list
      int sum = 0;
      for (int i: userfeed) {
          sum += i;
      }
      System.out.println(sum);  //printing the sum
        
    }
}

The output:

Enter a number:
15
Enter a number:
13
Enter a number:
14
Enter a number:
36
Enter a number:
-1
77
Ridwan
  • 172
  • 1
  • 14
  • Thanks for you answer. If you don't mind me asking, what does the do{ does to the code? – BaselE Feb 25 '21 at 17:59
  • Do-While Loop in Java is another type of loop control statement. Similar to while loop, the do-while loop also executes a block of code based on the condition. The only difference is that Do-While Loop in Java executes the code block at least once since it checks the condition at the end of the loop. – Ridwan Feb 25 '21 at 18:01
0

i tried to do it in a very simple way

public static void main(String[] args) {

    Scanner read = new Scanner(System.in);
    ArrayList<Integer> userfeed = new ArrayList<>();
    int luku = 0;
    int sum = 0;
    do{
        System.out.println("Syötä luvut:");
        luku = Integer.parseInt(read.nextLine());
        sum += luku;
        userfeed.add(luku);
    }while (luku != -1);

    System.out.println(sum + 1);
    }
Abel Kibebe
  • 29
  • 6