To extract specific information in the stack trace using regular expression I encountered a problem at http://regexone.com/example/6?
You can view the problem by clicking the link. 
There was required a regular expression to extract the method name, filename and the line number from a particular stack trace in an android development application.

I used the following regular expression to solve the problem :

at widget.List.([a-zA-Z]+).([A-Za-z]+\.java).(\d{3,4}).


The expression works for the problem but i don't think its the correct regular expression as there is no hat(^) and dollar ($) included in it.
If you wish to include the hat ^ and dollar $ signs, then the regex can be rewritten as:

^.*\s+at widget\.List\.(\w+)\((\w+\.java)\:(\d+)\)$


Ofcourse, you can still use \d{3,4} instead of \d+ but that'll result in you missing the errors in line numbers less than 100(like 1 to 99).

Similarly, you can use \w+ in place of [a-zA-Z]+ or simply, [A-z]+ will work too.