JRuby capture of System.out.println

silencer.rb

def silencer
  require 'java'

  java_import 'java.io.PrintStream'
  java_import 'java.io.ByteArrayOutputStream'
  java_import 'java.lang.System'

  sys_out_stream = System.out

  my_output_stream = ByteArrayOutputStream.new
  System.setOut(PrintStream.new(my_output_stream))

  yield
  my_output_stream.toString

ensure
  System.setOut(sys_out_stream)
end

output= silencer do
  System.out.println "Tacos Rule"
  puts "yo"
end

puts "output: #{output}"