QuantLib itself also provides Swig interfaces which can be used to create bindings for dozens of languages, Java included. Quoting:
SWIG is a software development tool that connects programs written in
C and C++ with a variety of high-level programming languages. SWIG is
used with different types of target languages including common
scripting languages such as Perl, PHP, Python, Tcl and Ruby. The list
of supported languages also includes non-scripting languages such as
C#, Common Lisp (CLISP, Allegro CL, CFFI, UFFI), D, Go language, Java,
Lua, Modula-3, OCAML, Octave and R.
See the QuantLib site for more on support for other languages and extensions.
On the other hand, JQuantLib is an independent project that was last reported to have a good sized portion of a prior release ported to Java.