Im looking for some info on standard techniques for validation of text
fields in JFormattedTextFields. They seem to have masks, input
validation methods, key listeners and so on which frankly seem a pain
in the backside to use. As an example I have one field which I want to
restrict the user to entering a value which is 0-N in value (N being
variable). I want to stop the use from leaving the field unless they
enter a valid value. I've got all this to work but its not nice and
seems hard to do. I ended up doing the following :-

Create the JFormattedTextField
Create a Numberformatter
SetFomratFactory on the text field using the formatter
Setup and InputVerifier on the textfield
Setup and input and actionmap for the enter key being pressed on the
text field

In the Input Verifier :
Get the formatter from the textfield
call stringbyvalue on the formatter to get the int value
if an int is returned without throwing an exception setvalue on the
setfield
if no expceptions are thrown return true otherwise return false.

In the actionmap:
basically the same as the input verifier but don't return anything.

If data is invalid I select everything in the textfield and don't
allow focus to be lost.

Now this all strikes me as a long winded way to do something that
should be fairly simple. I really just want a way of saying don't
allow focus to be lost in anyway unless the data is valid and here is
the check method. Is there a way to do this ?

Steve