The TrueZIP project has released versions 6.1 and 5.1.7. They write in: "This is another double release for TrueZIP. This is a bug fix and minor feature release. The primary focus has been to fix multithreading issues and enhance the Javadoc. The new feature is the extension of the ZIP archive driver family with CRC-32 checked versions for optional usage. Updating is considered critical for multithreaded environments such as application servers. TrueZIP is a virtual file system for transparent access to archive files such as ZIP, JAR, TAR, TAR.GZ and derivates using drop-in replacements for the well known File classes in the J2SE API."