run_compare.rb

require 'java'

class RunCompare
  import java.lang.Runnable
  import java.util.Comparator
  def compare(o1, o2)
    o1 - o2
  end
  def run
    puts "running..."
  end
end
array = [10, 3, 1, 6, 2].to_java

java.lang.Thread.new(RunCompare.new).start
java.util.Arrays.sort(array, RunCompare.new)

p array.to_a