ArrayList Scanner input help Java

Question

I am trying to write a code where you sort a given list of numbers, and I'm trying to do so using ArrayList. I am using a while loop to allow for repeated inputs. This is my code:

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

public class sortinggg {

    public static Scanner keyboard = new Scanner(System.in);
    public static ArrayList<Integer> number = new ArrayList<Integer>();

    public static void main (String [] args) {

        int count= 0;

        System.out.println("Enter your numbers.");

        while (keyboard.hasNextInt()); {
            number.add(keyboard.nextInt()); 
        }

The integer count is irrelevant right now, as I only use it when I am sorting the list.

The problem is that after I input my numbers, even if I type in a string (for example), the program doesn't move on to the next line of code. Am i missing anything here?

P.S. I tired looking up questions that have been asked previously on this topic, but none of the solutions suggested worked for me.Thank you for your help in advance!

while (keyboard.hasNextInt()); { Remove the semicolon. That ends your loop body. The number.add(keyboard.nextInt()); is in a different (non-loop) block. — Elliott Frisch
– Elliott Frisch, Commented Jul 16, 2018 at 18:36
Possible duplicate of Scanner issue when using nextLine after nextXXX — Lino
– Lino, Commented Jul 16, 2018 at 18:37
@ElliottFtisch That fixed it! Thank you for your help, new to Java and coding in general.. — Sirig Gurung
– Sirig Gurung, Commented Jul 16, 2018 at 18:42

Nitin Bisht · Accepted Answer · 2018-07-18 04:17:13Z

2

Try this:

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

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

        System.out.println("Enter your numbers:");

        while (keyboard.hasNextInt()) {
            number.add(keyboard.nextInt()); 
        }
    }
}

Modifications:

In while (keyboard.hasNextInt()); remove semicolon(;) at the end.

Here while loop will keep adding values to the arraylist until you provide int values.

answered Jul 18, 2018 at 4:17

Nitin Bisht

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Comments

Ravindra Ranwala · Accepted Answer · 2018-07-18 04:28:26Z

1

In the first place the ; just after the while is wrong. It does not let you to execute the body. Then how are you going to skip the loop. You may ask the end user to enter some special value and use it to break the loop. The corrected version is given below.

public static void main(String[] args) {
        int count = 0;

        System.out.println("Enter your numbers or -1 to skip.");

        while (keyboard.hasNextInt()) {
            int num = keyboard.nextInt();
            if (num == -1) {
                break;
            }
            number.add(num);

        }

        System.out.println(number);

    }

answered Jul 18, 2018 at 4:28

Ravindra Ranwala

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