jruby call method from super java class

Question

I am trying to create a subclass in jruby which overrides the keys method from the super java class properties cause i want to sort the entries in the properties class by the keys:

class SortedProperties < java.util.Properties  
 def keys
  keysEnum = super().keys()
  keyList = java.util.Vector.new
  keysEnum.elements.each do |element|
    puts element.to_s
    keyList.add(element.to_java(:String))
  end
  java.util.Collections.sort(keyList)
  puts keyList.elements().to_s
  return keyList.elements()
 end
end

I am doing definitly something wrong with the super statement but i don't know what. Searched a lot but can't find anything that points me to the correct call of the method keys() in the super class properties.

kares · Accepted Answer · 2014-12-04 07:06:41Z

1

you need make your brain "forget" the Java style super syntax and simply do it the Ruby way e.g.

class SortedProperties < java.util.Properties
 def keys
  keyList = java.util.Vector.new
  super.each do |element|
    keyList.add(element.to_java(:String))
  end
  java.util.Collections.sort(keyList)
  return keyList.elements()
 end
end

props = java.util.Properties.new
props.setProperty 'bbb', 'B'
props.setProperty 'aaa', 'A'
props.setProperty 'ccc', 'C'

props.store java.lang.System.out, ' raw-properties'

props = SortedProperties.new
props.setProperty 'bbb', 'B'
props.setProperty 'aaa', 'A'
props.setProperty 'ccc', 'C'

props.store java.lang.System.out, ' sorted-properties'

calling super already returns a result and it might be already Ruby converted by JRuby, even if it is not Java Enumeration/Collection are all Ruby Enumerable (or at least have a each method).

answered Dec 4, 2014 at 7:06

kares

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3 Comments

bladepit Over a year ago

thanks! this is exactly what i am searching for. another short question...do you know what i need to do to store comments with an leading "#" character in my properties? these will be ignored by the default java properties and will be removed

kares Over a year ago

I do not - would ask a separate (likely Java only) question for that ... sure someone will confirm if that's possible. but otherwise I would likely just use "pure" (J)Ruby to generate .properties files ... as it seems you're wasting time hacking java.util.Properties

bladepit Over a year ago

Yes i think you are right. Using the JRuby properties files would be more efficient. Thanks for you help!

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