Selection of libraries for Java which are useful and not provided with Java.

- Unix Sockets Library: This is a collection of classes and native code to
  allow you to read and write Unix sockets in Java.
- Debug Library: This is a comprehensive logging and debugging solution.
- CGI Library: This is a collection of classes and native code to allow you to
  write CGI applications in Java.
- I/O Library: This provides a few much needed extensions to the Java I/O
  subsystem. Firstly, there is a class which will connect and InputStream with
  an OutputStream and copy data between them.  Secondly there are two classes
  for inserting into an Input or OutputStream pipe a command line command, so
  that everything is piped through that command.  Thirdly there are a pair of
  classes for splitting streams in two. This can either be to two OuputStreams,
  or to an OutputStream and a file. Equivelent to the UNIX tool tee in UNIX
  pipes.
- Hexdump: This class formats byte-arrays in hex and ascii for display.

WWW: http://www.matthew.ath.cx/projects/java/