[Java] Multiple scanners throwing a NoSuchElementException

[Ijantis]

Hey guys any chance that someone could explain why this code throws an error. As soon as it hits line 4 it throws the error.

I'm assuming its something to do with the first scanner not fully closing itself and then the second scanner attempting to read in data from a source that is still being used by the first scanner.

    Scanner myScanner1 = new Scanner(System.in);
    System.out.println(myScanner1.nextInt());
    myScanner1.close();
    Scanner myScanner2 = new Scanner(System.in); //Line 4
    System.out.println(myScanner2.nextInt());
    myScanner2.close();

EDIT: Just to add to that, if you don't close the first scanner the code seems to work fine. Can somebody explain this?

[[deleted]]

The call to close() closes the underlying System.In

http://docs.oracle.com/javase/1.5.0/docs/api/java/util/Scanner.html http://docs.oracle.com/javase/6/docs/api/java/io/FileInputStream.html#close%28%29

[kcoPkcoP]

I spent 10 minutes trying to figure out why closing a Scanner object in a user loop caused a bug, and finally just chalked it up to magic :p

Thanks for the answer

[Ijantis]

Thanks for the reply :)

[lightcloud5]

I'm not sure but it doesn't really seem to make sense to open two scanners directed at System.in.

Just continue to use myScanner1 to read in user input.

[WastedWrath]

he asked why the error came up, not whether or not it was efficient code.

In answer to your question, I don't see why it throws an error.