Minor Description
ZipFile (and SevenZFile) currently require a File argument, but it would be nice to support in-memory byte buffers rather than requiring temp files. Perhaps create a new SeekableInputStream class (or SeekableDataInput interface) and add corresponding constructors.
For convenience, perhaps also add a utility class that wraps a ByteBuffer and/or byte[] and implements the new interface.
(The sevenz package appears to have a similar limitation, so it might make sense to add the support there at the same time, but I personally don't have a need for that.)