Java™

The caffeine boost you need for your late-night coding sprints.

Install

gem install java or add gem 'java' to your Gemfile.

This gem requires Ruby 2.1.0+.

Usage

Currently, the following keywords are supported: new, void, byte, short, int, long, float, double, bool, char.

require 'java'

class MyClass
  public def initialize(name)
    @name = name
  end

  public void def main()
    puts "This is the main method from #{@name}"
    return nil
  end

  public int def returns_int()
    1
  end

  public int def not_int()
    'not int'
  end

  public byte def returns_byte()
    1
  end

  public byte def not_byte()
    128
  end
end

# >> obj = new MyClass("my class")
# => #<MyClass:0x000001018333d8 @name="my class">
# >> obj.main()
# This is the main method from my class
# => nil
# >> obj.returns_int()
# => 1
# >> obj.not_int()
# TypeError: Expected not_int to return int but got "not int" instead
# >> obj.returns_byte()
# => 1
# >> obj.not_byte()
# TypeError: Expected not_byte to return byte but got 128 instead

Production Ready?

It has tests, if that's what you are asking.

Future Work

• Bug: typed private and protected methods doesn't work
• Bug: Kernel defines Array, Complex, Float, Hash, Integer, Rational and String which breaks new String() etc
• Support more keywords: static, final, etc

Credits

Java™ is a registered trademark of Oracle and/or its affiliates.

@tenderlove and @jeremy first brought this to my attention. @amatsuda also has a similar gist.