There are many java projects

XBIS is an encoding format for XML documents that is fully convertible to and from text, with information set equivalence between the original document text and regenerated document text. It's intended for use in transmitting XML documents ...

Xazzle is an open source XHTML generator written in Java.

A java library for parsing arbitrarily complex command-lines, with both long and short options and switches.

Framework to simplify the task of writing and executing threads in Java. The developer writes a Callable with annotations.

Built on the top of Cobertura, TestCoverageSpy injects Cobertura code into java classes on the fly (load time). So it makes test coverage analysis for Web Application testing, or other integration/functional testing, a bit simpler.

Faster Java implementations of hypot, expm1, cos, sinh, cosh, tanh, asin, acos, atan and atan2

Experimental Java 8 backport of the incubating Java 10 HTTP/2 and WebSocket API

Sorb helps create service trees in Java.

SchemaCrawler is an open-source Java API that makes working with database metadata as easy as working with plain old Java objects. SchemaCrawler is also a database schema discovery and comprehension tool.