Runtime error- java.util.NoSuchElementException

Question

program to input 2d array using Scanner class but output shows:

Runtime error:
 NZEC
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 Wocode.main(Main.java:9)

Code snippet:

import java.lang.*;
    import java.util.*;
    import java.util.Scanner;

     class Wocode {
        public static void main(String args[]) {
            Scanner s=new Scanner(System.in);
                int m=s.nextInt();
                int n=s.nextInt();
                int A[][] = new int[m][n];
                for(int i=0;i<m;i++)
                {
                  for(int j=0;j<n;j++)
                    {
                     A[i][j]=s.nextInt();
                    }
                }     
    }
    }

what do you input? What do you expect the code to do when you do input anything other than an integer? — luk2302, Apr 01 '19 at 18:29

score 1 · Answer 1 · answered Apr 01 '19 at 18:57

Don't use nextInt() as it doesn't clean the line in the buffer. So, a better way to the user input is to use s.nextLine(). To take integer input do

Integer.parseInt(s.nextLine())

When you use nextInt() it takes the input but the line after the input is still there in the buffer and when the another nextInt() looks for the input you get the exception.

score 0 · Answer 2 · answered Apr 01 '19 at 18:52

0

I agree to cricket_007. Need to check hasNext() method before calling s.next() as below. <if(s.hasNextInt()){ A[i][j]= s.nextInt(); }>

answered Apr 01 '19 at 18:52

Krishna

21
3

score 0 · Answer 3 · answered Apr 01 '19 at 18:57

0

Instead of calling hasNextInt, you should use a blocking readLine call and cast to an integer instead.

int n = Integer.parseInt(s.nextLine());

answered Apr 01 '19 at 18:57

washcloth

2,730
18
29

catch23 · Answer 4 · 2019-04-01T19:38:28.173

Your code has a few mistakes.

Here is a sequence, how to solve them:

you have to say to a user what exactly the program expects as input
validate if the user entered correct values
parse entered values
use that values

You didn't do some steps. Therefore, your solution isn't even executed.

Here is some code snippet, which fits all steps:

class Wocode {
    public static void main(String args[]) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Please enter two numbers (separated by space): ");

        if (scanner.hasNext()) {
            String[] input = scanner.nextLine().split(" ");
            if (input.length == 2) {
                int firstNumber = Integer.valueOf(input[0]);
                int secondNumber = Integer.valueOf(input[1]);

                int arr[][] = new int[firstNumber][secondNumber];

                for (int rows = 0; rows < firstNumber; rows++) {
                    for (int columns = 0; columns < secondNumber; columns++) {
                        arr[rows][columns] = firstNumber + secondNumber;
                        System.out.print(String.format("%4s", arr[rows][columns]));
                    }
                    System.out.println();
                }
            } else {
                System.err.println("You have to enter two digits, separated by space!");
            }
        }
    }
}

Output:

Please enter two numbers (separated by space): 3 5
   8   8   8   8   8
   8   8   8   8   8
   8   8   8   8   8

Useful links:

Runtime error- java.util.NoSuchElementException

4 Answers4