JCPP is a complete, compliant, standalone, pure Java implementation of the C preprocessor. It is intended to be of use to people writing C-style compilers in Java using tools like sablecc, antlr, JLex, CUP, and so forth. It has been used to successfully preprocess much of the source code of the GNU C library.
Apache XML Graphics Commons is a library that consists of several reusable components used by Apache Batik and Apache FOP. Many of these components can easily be used separately outside the domains of SVG and XSL-FO. You will find components such as a PDF library, an RTF library, Graphics2D implementations that let you generate PDF and PostScript files, and much more.
Rome is a set of Atom/RSS Java utilities that make it easy to work in Java with most syndication formats. It accepts all current flavors of RSS (0.90, 0.91, 0.92, 0.93, 0.94, 1.0, and 2.0) and Atom 0.3 feeds. Rome includes a set of parsers and generators for the various flavors of feeds, as well as converters to convert from one format to another. The parsers can give you back Java objects that are either specific for the format you want to work with, or a generic normalized SyndFeed object that lets you work on with the data without bothering about the underlying format.
Cypress is an open-source Cascading Style Sheet (CSS) parser that lets you add well-documented, standardized name/value pairs (a.k.a. CSS style properties) to your own XML markup languages. It supports inline styles so you can add style properties to individual XML tags using the style attribute or external style sheets so that you can store style rules for reuse in separate, XML-free text documents. Cypress supports three forms of selectors to match your XML tags and style rules, that is, element selectors, class selectors, and id selectors.