This is my attempt at a software project to integrate some music theory knowledge that's still in my head into something useful. This is currently in alpha development stage i.e. lots of busted stuff. My hope is to get enough feedback in the design to make it useful for me and for others. Use it as Java sample code if you like.
jFonia is a framework/API for music, focusing on symbolical (discrete) data such as notes, clefs, measures etc.
It is a low level framework, aiming to facilitate the development of high level music software, such as score players, viewers, editors, analysis and composition tools etc.
Music21 is a set of tools for helping scholars and other active listeners answer questions about music quickly and simply. If you’ve ever asked yourself a question like, “I wonder how often Bach does that” or “I wish I knew which band was the first to use these chords in this order,” or “I’ll bet we’d know more about Renaissance counterpoint (or Indian ragas or post-tonal pitch structures or the form of minuets) if I could write a program to automatically write more of them,” then music21 can help you with your work.