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Looping  RSS feed

 
chop vick
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New to java and having a problem getting my loop to work. program runs and stops the user from inputting anything less than zero but not stopping them from inputting anything over 1000.

Also having a problem with the NumberFormatException as i can't let user input letters either!

Once loop is working i then need to read user input in JOptionPane and pass it to a constructor in a different class.

First time on this so thanks for any help given!!

 
chop vick
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changed my code a bit and program now stops user from inputting anything over 1000. But how do i get it to stop user from inputting letters or words?!!\


 
Junilu Lacar
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Do you understand when the catch (NumberFormatException e) on line 36 will be executed?  Do you know how to use loops?

See Java Tutorial - Exceptions
See Java Tutorial - Loops
 
chop vick
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ok so have came up with this now but loop finishes after user is prompted to enter new number after first input is invalid. what to do?

 
Dave Tolls
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I don't see a loop in that latest code?
 
Campbell Ritchie
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Welcome to the Ranch

I can see a problem, I am afraid. You have got a method inside a display component which isn't part of the display. Testing whether the input is a number or not is part of your “business logic” and ought to be in a “business class”. Which isn't the opposite of economy class. You shou‍ld have a method which tests whether the input is a number or not; the display class can take action, e.g. remove the entry from the text field.
There are better ways to test whether a String represents a number than catching Exceptions. You will find some suggestions in this thread from last Summer.
 
It is sorta covered in the JavaRanch Style Guide.
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