Since OpenJDK 9 is installed for the recent update on Parrot Security OS 3.11, some Java applications that are using OpenJDK 8 may not work properly. We can fallback to OpenJDK 8 easily.
sudo update-alternatives --config java
Then select OpenJDK 8 or OpenJRE 8 when necessary. You can change back to OpenJDK 9 at any time with the same command.
That's all! See you.