FlatPack came out of the frustration of having to mix file parsing logic with business logic.
FlatPack on SourceForge: a Java (1.4+) flat file parser that handles CSV, fixed length and custom delimiters. The formats are configured in XML, it is fast and released under Apache license 2.0.
Substrings in a fixed width parse can be daunting to deal with when trying to analyze what existing code is doing, and what about when you have no comments...
We also provide delimited file parsing; works with any delimiter / qualifier, multiline records, delimiter or qualifier allowed in column value.