Reinstall java ?

Hello!

Java in my macOS High Sierra 10.13.3 seems to be broken.

Java control panel on settings, does not even start.

java command line works, but trying javaws it results in "Bad installation: JAVAWS_HOME not set: No such file or directory" (I suppose that's why can run applets on firefox, the applet is just downloaded)

Is there any concise documentation that explain who to do a full java uninstall and how to make a clean reinstall?

I goolged a lot, found nothing helping to fix my problem.

Any help will be truly appreciated.

Thank you so much.