SilverTunnel-NG is a Java library that handles all the Tor connection work for easy integration into new or existing projects. You can connect to any server on the Internet anonymously; connect to a hidden service inside the Tor network; provide a hidden service; and more.
Orchid is a Tor client and library written in pure Java. It exposes a SOCKS5 listener for use as a Tor client, and can also be used to (nearly) transparently Torify new and existing applications that run on the JVM. It also runs on Android devices.