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Looping in exceptions

Carlos Obregon
Greenhorn

Joined: May 26, 2009
Posts: 18
I'm trying to catch a number from a Scanner. I thought that I could catch the InputMismatchException and re-ask the user to submit another real number.

I use this but if I raise the exception it keeps in an infinite loop:



Thanks!
Campbell Ritchie
Sheriff

Joined: Oct 13, 2005
Posts: 37907
    
  22
Because of the exception, the done variable remains false for ever. The Scanner continues to look at the token which wasn't a number, so consume that token with a call to in.next(); inside the catch. No need to do anything with that token.

Then you can enter a new token, and the loop can go round once more.
Rob Spoor
Sheriff

Joined: Oct 27, 2005
Posts: 19649
    
  18

You shouldn't use exceptions this way if there are valid checking methods available.
An improved version:


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subject: Looping in exceptions
 
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