JRuby's include_package (mentioned in https://github.com/jruby/jruby/wiki/CallingJavaFromJRuby) includes Java packages in JRuby on const_missing. However, it does not trickle down to subclasses/submodules nor nested-classes/nested-modules.

nested_inherited_jruby_include_package patches up JRuby to add that capability.

Example (nesting):

require 'nested_inherited_jruby_include_package'

class OuterClass
  include_package java.util
  class InnerClass
    def initialize
      p Arrays.asList(1, 2, 3)
    end
  end
end

OuterClass::InnerClass.new
# prints #<Java::JavaUtil::Arrays::ArrayList:0x233fe9b6>

Example (inheritance):

require 'nested_inherited_jruby_include_package'

class SuperClass
  include_package java.util
end

class SubClass < SuperClass
  def initialize
    p Arrays.asList(1, 2, 3)
  end
end

SubClass.new
# prints #<Java::JavaUtil::Arrays::ArrayList:0x7ce3cb8e>

Example (java inheritance):

module GUI
  include_package 'javax.swing'
  include_package 'java.awt.image' # BufferedImage
  # bellow won't work without accessing BufferedImage before :
  class ShowImage < JFrame
    p BufferedImage.new(10, 20, BufferedImage::TYPE_BYTE_BINARY)
  end
end
# prints #<Java::JavaAwtImage::BufferedImage:0x2f112965>

More examples can be found in:

spec/lib/core/src/main/ruby/jruby/java/core_ext/module_spec.rb

Add the following to Gemfile:

gem 'nested_inherited_jruby_include_package', '~> 0.3.0'

And, then run:

jruby -S bundle install

If you are not using Bundler, run:

jruby -S gem install nested_inherited_jruby_include_package -v 0.3.0

Then add this line to your code:

require 'nested_inherited_jruby_include_package'

This gem relies on Module#const_missing after it aliases it to Module#const_missing_without_nested_inherited_jruby_include_package

As such, it works optimally if your project and loaded gems do not override Module#const_missing

To avoid method and constant pollution in Module, the implementation intentionally trades off code clarity for lack of pollution by not relying on methods, yet local lambdas, in modularizing logic.

This is an early alpha. It has only been used in a couple of projects. As such, there are no guarantees for its functionality. Please report any issues you might discover when using on your own projects.

CHANGELOG.md

The MIT License

LICENSE.txt

Copyright (c) 2020 Andy Maleh