NoSuchElement using scanner twice

Question

I'm working on a code that reads user input, so I've made a procedure that does just that, reads and return the string. when calling it twice from another procedure, returns a NoSuchElementException error which I can't figure out why.

input reader proc:

    public static String read() {
    
72    Scanner leer = new Scanner(System.in);
73    String entry = leer.nextLine();
74    leer.close();
75    return entry;
    
    }

how I'm using it:

...
    System.out.println("input value ");
    String padre = Entrada.read();
    System.out.println("input values ");
27  String reemplazado = Entrada.read();
...

I'm getting

Exception in thread "main" java.util.NoSuchElementException: No line found
    at java.util.Scanner.nextLine(Unknown Source)
    at modulocarga.Entrada.leerEntradaUsuario(Entrada.java:73)
    at modulocarga.TablaSimbolica.addTaxonomica(TablaSimbolica.java:27)
    at modulocarga.Principal.main(Principal.java:8)

works fine the first time I call it then it crashes. what could it be?

perhaps your first input contains a line separator , but the second input does not , and the scanner does not find the line correctly - and hence the NSEE — Bhaskar, Apr 28 '14 at 22:20
Please see here: http://stackoverflow.com/questions/4232588/how-to-use-multiple-scanner-objects-on-system-in?rq=1 — maksimov, Apr 28 '14 at 22:33

Reimeus · Accepted Answer · 2014-04-28T23:49:29.157

0

Since there is only one InputStream used its no longer possible to read from the closed input source the second time the method is called

Either refrain from closing the Scanner (or create a single class instance of Scanner to be closed at application end)

edited Apr 28 '14 at 23:49

answered Apr 28 '14 at 22:18

Reimeus

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If the underlying stream is closed , then attempting to read on that stream should throw `IOException` - and not NSEE – Bhaskar Apr 28 '14 at 22:24
but then again - maybe the `Scanner` wraps up an `IOException` into a `NSEE` . – Bhaskar Apr 28 '14 at 22:26
removing the .close() solved the issue, can it bring other problems? its not necessary? – user3583107 Apr 28 '14 at 23:57
no, quite the opposite, dont close the `Scanner` unless you want it to fail – Reimeus Apr 29 '14 at 01:43

score 0 · Answer 2 · edited May 23 '17 at 12:20

0

This is because your scanner is linked to System.in and when you're closing your scanner, it automatically closes System.in as well. What you want to do is to just close your scanner without closing System.in.

This would help: Close Scanner without closing System.in

edited May 23 '17 at 12:20

Community

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answered Apr 28 '14 at 23:25

jianweichuah

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NoSuchElement using scanner twice

2 Answers2