RubyMotion for Android utility that converts a java.util.HashMap instance to a Ruby hash

HashMapToHash.rb

# Utility class that converts a java.util.HashMap instance to a Ruby Hash. RubyMotion will
# start supporting this out of the box at some point, but until then, this can be used
# as a workaround: http://hipbyte.myjetbrains.com/youtrack/issue/RM-725
#
# Usage:
#   HashMapToHash.convert(hashmap)
#
# This supports nested hashes and should assure that all Java-based values are properly converted
# to their Ruby counterparts (i.e. java.lang.String => String).
#
# This has not been extensively tested, or optimized for performance. It should work well enough
# for simple cases, but may well fall over with a large HashMap.
#
class HashMapToHash

  def self.convert(java_hashmap)
    HashMapToHash.new.to_hash(java_hashmap)
  end

  def to_hash(hm)
    return nil if hm.nil?
    Hash.new.tap do |h|
      it = hm.entrySet().iterator();
      while it.hasNext() do
        entry = it.next()
        h[entry.getKey()] = convert_value(entry.getValue())
        it.remove()
      end
    end
  end

  private

  def convert_value(value)
    new_value ||= to_hash(value)    if hashmap?(value)
    new_value ||= to_array(value)   if array?(value)
    new_value ||= to_boolean(value) if boolean?(value)
    new_value ||= nil               if null?(value)
    new_value ||= value.to_s        if java_string?(value)
    new_value ||= value
  end

  def hashmap?(value)
    value.class.to_s.end_with?("HashMap")
  end

  def array?(value)
    value.is_a?(Array)
  end

  def boolean?(value)
    ["true","false"].include?(value.to_s.downcase)
  end

  def null?(value)
    value.nil? || value.to_s.downcase == "null"
  end

  def java_string?(value)
    value.class.to_s == "java.lang.String"
  end

  def to_array(array)
    # currently, Java arrays are correctly converted to Array objects - we just need to make
    # sure that the values are correctly converted
    array.map { |value| convert_value(value) }
  end

  def to_boolean(value)
    value.to_s.downcase == "true"
  end

end