Problem with focus and selecting text in jtextfield

Question

I have problem with jtexfield. I know that solution will be very simple but I can't figure it out.
This is simplified version of situation:
I have a jframe, jtextfield and jbutton. User can put numbers (0-10000) separated with commas to textfield and save those numbers by pressing jbutton.
When jbutton is pressed I have a validator which checks that jtextfield contains only numbers and commas. If validator sees that there are invalid characters, a messagebox is launched which tells to user whats wrong.
Now comes the tricky part.
When user presses ok from messagebox, jtextfield should select the character which validator said was invalid so that user can replace it by pressing a number or comma.
I have the invalid character, but how can you get the focus to jtextfield and select only the character which was invalid?
I tried requestFocus(), but it selected whole text in jtextfield and after that command I couldn't set selected text. I tried with commands setSelectionStart(int), setSelectionEnd(int) and select(int,int).
Then I tried to use Caret and select text with that. It selected the character I wanted, but the focus wasn't really there because it didn't have keyFocus (or something like that).
Is there a simple way of doing this?

Answer 1

textField.requestFocusInWindow();
textField.select(...);The above should work, although read the API on the select(...) method for the newer recommended approach on how to do selection.
If you need further help then you need to create a "Short, Self Contained, Compilable and Executable, Example Program (SSCCE)",
see http://homepage1.nifty.com/algafield/sscce.html,
that demonstrates the incorrect behaviour, because I can't guess exactly what you are doing based on the information provided.
Don't forget to use the "Code Formatting Tags",
see http://forum.java.sun.com/help.jspa?sec=formatting,
so the posted code retains its original formatting.