JRuby: import vs include vs java_import vs include_class

Question

why so many different ways to include Java classes into JRuby? What are the differences? Which one should I use?

Answer 1

import doesn't play well with Rake, so it's discouraged. java_import is the newest, and recommended. include_class has been deprecated. Apart from that they all do the same thing, and are actually aliases of each other.

import is an alias for java_import and java_import calls include_class.

Answer 2

You can find quite a few examples about working with Java classes at:
https://github.com/jruby/jruby/wiki/CallingJavaFromJRuby

It states, that you should use java_import instead of import due to the JRUBY-3171 bug.
Also include_class is or will be deprecated (JRUBY-3797) in favor of java_import.

Currently java_import is the recommended way to import a Java class.