Bind Java objects to ruby hashes

Question

Is there a way to create ruby value objects or hashes from java objects in jruby application ? Thank you.

I assume you read this page including some the links at the bottom? github.com/jruby/jruby/wiki/CallingJavaFromJRuby — Michael Kohl
– Michael Kohl, Commented Mar 17, 2011 at 15:43

Sébastien Le Callonnec · Accepted Answer · 2011-03-17 16:47:26Z

3

I am not sure whether this is what you are trying to achieve, but to convert a Java object into a ruby hash, you could do something like this:

require 'java'
java_import 'YourJavaClass'

a = YourJavaClass.new
hash = {}
a.java_class.fields.each{ |var| hash[var.name] = var.value(a) }
p hash

This assumes that the instance variables are accessible (public). If they are not, you may need to make them accessible with something like:

a.java_class.declared_fields.each{ |var| var.accessible = true; hash[var.name] = var.value(a) }

(Note that this time it uses declared_fields)

answered Mar 17, 2011 at 16:47

Sébastien Le Callonnec

27k8 gold badges70 silver badges83 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Fivell Over a year ago

thanks declared_fields works fine but I need totally ruby native hash, but in this way values can be such for example "createDatetime"=>#<Java::JavaUtil::Date:0x34a205d1>, I need to get all properties that have accessors to hash wich should have only ruby type values .

Fivell · Accepted Answer · 2011-03-21 17:42:06Z

2

Names and Beans Convention gives us next opportunity for properties with accessors

def java_to_hash(java_obj)
    hash = {}
    java_obj.methods.grep(/get_/).each do |accessor|

      if accessor.eql? "get_class" then
        next
      end

      #get_user_name => user_name
      method_name = accessor[4..-1]

      if java_obj.respond_to?(method_name)
        hash[method_name.to_sym] = java_obj.send(accessor.to_sym)
      end
    end
    hash
end

answered Mar 21, 2011 at 17:42

Fivell

11.9k4 gold badges63 silver badges101 bronze badges

1 Comment

Gary S. Weaver Over a year ago

That almost worked for me. I had to change the one conditional to: next if 'get_class' == accessor.try(:to_s)

Collectives™ on Stack Overflow

Bind Java objects to ruby hashes

2 Answers 2

1 Comment

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related