Why do I get this noelementexception again and again in Java and how do I fix it?

Question

I have the following code:

 while (true) {
     if (flag == 0) {
        System.out.println("1. Display all staff");
        System.out.println("2. Clear schedule");
        System.out.println("3. Display schedule");
        System.out.println("4. Assign shift to casual employee");
        System.out.println("5. Assign shifts to permanent employee");
        System.out.println("6. Calculate total weekly wages");
        System.out.println("7. Exit Program");

        while (true) {
            System.out.println("Enter your selection");
            Scanner in = new Scanner(System.in); // in these lines
            n = in.nextInt();   // in these lines
            if (n <= 0 || n > 7) {
                System.out.println("Invalid Selection - must be between 1 and 7.");
                break;
            }
        }
    }

Now, whenever I run the program, it gives me the following compilation error:

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 EmployeeDriverSystem.main(Main.java:61)

Line 61 is the line with the comment "in these lines"

Is it letting you type anything? That's a runtime exception, not a compilation exception, by the way — OneCricketeer, Jun 02 '16 at 12:40
Also, a [mcve] would be nice. `int n` is not declared in the code you've shown — OneCricketeer, Jun 02 '16 at 12:43
You may need to call nextLine after nextInt to clear the buffer — MadProgrammer, Jun 02 '16 at 12:44
because of n-variable is no where declared. please, declare it first then use it. — Vishal Gajera, Jun 02 '16 at 12:45
Your code is inconveniently cutted. I'm pretty sure you have a `Scanner#close` inside your loop. See the dupe why this is not a good idea. — Tom, Jun 02 '16 at 12:45
@Tom, I have added the link of the original code. Please see it once to check where the error is. — Harry Lewis, Jun 02 '16 at 12:48
@vishalgajera, I have edited the original post to include my link to the code. — Harry Lewis, Jun 02 '16 at 12:49
Harry, do you run your code only on ideone? Not locally? ideone expects the whole input prior running the code. It doesn't wait for you to input something and will throw an exception if the required input isn't there. — Tom, Jun 02 '16 at 12:54

Abdul Fatir · Answer 1 · 2016-06-02T12:56:16.373

1

You posted this code some time back. What you've ~~not~~ now mentioned is that you're trying to run it on ideone where the execution is not paused for user input, instead you have to pass the standard input before running the program. Try this on your computer in a console and it will run without and hassles any with no NoSuchElementException.

You're getting user input in an infinite while loop on ideone. It will not work as expected because you cannot provide infinite input beforehand unless you provide the input for exit condition in the end.

EDIT

As an example for people who downvote for no reason: http://ideone.com/dmBMJO
You get java.util.NoSuchElementException because standard input is empty.

edited Jun 02 '16 at 12:56

answered Jun 02 '16 at 12:50

Abdul Fatir

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Care to explain the downvote? – Abdul Fatir Jun 02 '16 at 12:52
I haven't voted, but I guess the voter thinks that this should be a comment. Even though it looks like the correct explanation to OPs problem and therefore is a valid answer. (btw: I wrote that before your edit, but forgot to commit it :P) – Tom Jun 02 '16 at 14:54
@Tom Yes, I saw that in your comment. :D About the down-vote, people should at least be courteous enough to mention the reason. – Abdul Fatir Jun 02 '16 at 15:23
Well some users don't do that anymore, because they experienced revenge downvotes by the downvoted user, instead of having a mature discussion about the downvoted post and what should be improved. Kind of a bad situation for both sites. – Tom Jun 02 '16 at 15:32

Why do I get this noelementexception again and again in Java and how do I fix it?

1 Answers1