PL/Java is a free add-on module that brings Java™ Stored Procedures, Triggers, and Functions to the PostgreSQL™ backend.
Java C Other
Latest commit 0c38d9a Oct 25, 2016 @jcflack jcflack Merge branch 'REL1_5_STABLE'
Its next version has been bumped to 1.5.1-SNAPSHOT. The master next
version remains 1.6.0-SNAPSHOT (accepting the old value for each merge
conflict), leaving only the addition of 1.5.0 to the versions that
ALTER EXTENSION can update from.

README.md

PL/Java

PL/Java is a free add-on module that brings Java™ Stored Procedures, Triggers, and Functions to the PostgreSQL™ backend.

More information about this project can be found in the PL/Java Wiki and on the project information site.