Conditional Regular Expression in Java?

Question

I have a conditional regular expression that works on regex test websites, such as regexlib.com, but cannot get it to work in my Java application.

But, http://www.

Answer 1

How about just doing this instead?

(?:[a-zA-Z0-9]{6})?(317866?)

Or if you know that the longer version always start with a letter then you can use this:

(?:[a-zA-Z][a-zA-Z0-9]{5})?(317866?)

It will first try to match 6 alphanumerics followed by 31786 or 317866, and if that fails it will then backtrack and try matching 31786 or 317866.

Answer 2

Conditional expressions are not supported by java.util.regex.Pattern class. To get around that you could use a 3rd party regexp library such as JRegex