Hunspell is a very powerful Free spellchecker, that understands the strange rules that govern languages like hungarian, german and danish, unfortunatly it doesn't have Java bindings by default.
This page presents the JNA Java bindings that I've written for my employer
The code is tri-licensed under LGPL/GPL/MPL just like Hunspell itself, this means that the user of the library can choose the license to best fit the project.
Regarding the LGPL/GPL version: Feel free to use the code under version 2.0 or later.
So far the code works on the platforms I have needed to make work, but there is no reason that it shouldn't work on all platforms supported by both JNA+Hunspell (marked No below):
The code is used in production by several companies and has been under QA for a good while now, so quality should be good enough for most use, but it's always recomended that you do your own testing.
Head on over to the github page, the readme.txt file has the rest of the details.