Looping with scanner

Question

I am trying to make a triangular numbers generator that asks the user how many triangular numbers it would like them to generate. These are my errors:

Exception in thread "main" java.util.NoSuchElementException
    at java.util.Scanner.throwFor(Scanner.java:862)
    at java.util.Scanner.next(Scanner.java:1485)
    at java.util.Scanner.nextInt(Scanner.java:2117)
    at java.util.Scanner.nextInt(Scanner.java:2076)
    at TriangularNumbers.main(TriangularNumbers.java:11)


    import java.util.Scanner;

    public class TriangularNumbers {
        public static void main(String args[]) {
            while(true){
                long tnumber = 1L;
                long amount = 2L;
                System.out.println("Welcome to the triangular numbers           calculator!");
                System.out.println("Type in the amount of triangular numbers to be generated!");
                Scanner reps = new Scanner(System.in);
                long repeats = reps.nextInt();
                reps.close();
                long i = 0L;
                while (i < repeats) {
                    i = i + 1;
                    System.out.println(i + ". " + tnumber);
                    tnumber = tnumber + amount;
                    amount = (amount + 1);
                }
                System.out.println("Done generating!");
            }
        }

    }

Everything works fine until it reaches the stage of the second user input.

uhhhh sorry wrong dupe, don´t do `reps.close();` in the loop, you´re closing the `System.in` Stream and wont be able to input anymore afterwards. — SomeJavaGuy, Oct 12 '16 at 05:47
Possible duplicate of [Scanner is skipping nextLine() after using next(), nextInt() or other nextFoo() methods](http://stackoverflow.com/questions/13102045/scanner-is-skipping-nextline-after-using-next-nextint-or-other-nextfoo) — xenteros, Oct 12 '16 at 08:45

Noushad · Answer 1 · 2016-10-12T05:56:16.210

-1

Why cant you try this way.?

import java.util.Scanner;

public class TriangularNumbers {
    public static void main(String args[]) {
        Scanner reps = new Scanner(System.in);
        while(true){
            long tnumber = 1L;
            long amount = 2L;
            System.out.println("Welcome to the triangular numbers           calculator!");
            System.out.println("Type in the amount of triangular numbers to be generated!");

            long repeats = reps.nextInt();
            if(reps == 0L) break; //Considering reps ==0 as the terminating condition to get out of the loop
            long i = 0L;
            while (i < repeats) {
                i = i + 1;
                System.out.println(i + ". " + tnumber);
                tnumber = tnumber + amount;
                amount = (amount + 1);
            }
            System.out.println("Done generating!");
            reps.nextLine(); // Has to be there in case of run out of tokens
        }
        reps.close();
    }

}

edited Oct 12 '16 at 05:56

answered Oct 12 '16 at 05:46

Noushad

369
3
10

reps.close() will be unreachable – Amer Qarabsa Oct 12 '16 at 05:49
As Amer said I don't think reps.close() would ever occur, or does that not matter? – Michael Duffett Oct 12 '16 at 05:51
It was a solution to your problem. Logic always belong to the the coder. :D – Noushad Oct 13 '16 at 05:29
It says that long and scanner can't go together. – Michael Duffett Oct 13 '16 at 20:54

score -2 · Answer 2 · answered Oct 12 '16 at 05:51

Pleae change code like this:

 long tnumber = 1L;
    long amount = 2L;
    System.out.println("Welcome to the triangular numbers           calculator!");
    System.out.println("Type in the amount of triangular numbers to be generated!");
    Scanner reps = new Scanner(System.in);
    long repeats = reps.nextInt();
    reps.close();
    long i = 0L;
    do {
        i = i + 1;
        System.out.println(i + ". " + tnumber);
        tnumber = tnumber + amount;
        amount = (amount + 1);
        System.out.println("Done generating!");
    } while (i < repeats);

Looping with scanner

2 Answers2