On the Debuggable blog, Felix Geisendorfer shows how to create a string parser that allows you to pull out parts of the string you don't currently want manipulated to be put back later.

If you've ever written any non-trivial String processing code, you've probably ran into the situation where you wanted to exclude certain parts of your string for a certain operation. Usually that would mean you have to tokenize your string, or adjust the operation you want to run so it doesn't affect the part of the string you want to exclude from it. Both of those solutions can be fairly time intensive so I was looking for a shortcut and found one.

He provides the code for this string substitution class, a method substitute() that matches based on a regular expression and, if found, stores the parts for later use.