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JRuby FileChooser example

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I’m working on the next version of It’s All Text! and it needs a stand-alone editor server. I’ve had a couple false starts other languages but I’m thinking it should be Java or JRuby so that it is fairly portable without me having too much grief. In addition, installing Java is a little more acceptable to a random group of people than installing Ruby (at the moment, it may change in the future).

Actually, I found two projects that make it much more likely I’ll use JRuby instead of Java:

  1. rawr - a gem to bundle your JRuby project into an app, .exe or .jar. I won’t have to force the user to install Java.
  2. monkeybars - a gem to providing an MVC model for swing development. You use netbeans, whatever, to build the V, and ruby to do the M and C.

The snippet below allows the user to pick an editor application from their system. It should be able to be ported to pure Java without too much grief if I want to.

The interesting bits are the FileFilter subclass and the OS detection (JRuby specific).

require 'rbconfig'
require 'pathname'

class AppFilter < Java::javax::swing::filechooser::FileFilter
  def accept fobj
    return true if fobj.canExecute
    return fobj.isDirectory
  end

  def getDescription
    "Applications"
  end
end


# Detect OS
OS = case Config::CONFIG['host_os']
  when /darwin/      then :mac
  when /mswin|mingw/ then :windows
else
  :unix
end

# Asks the user to choose an editor.
# Returns either a Pathname object or nil (if canceled)
def pickEditor
  # Create a FileChooser
  fc = Java::javax::swing::JFileChooser.new("JRuby panel")
  fc.set_dialog_title("Please select your editor")
  fc.setFileFilter AppFilter.new

  if :mac == OS
    fc.setCurrentDirectory(java.io.File.new("/Applications"))
  elsif :windows == OS
    fc.setCurrentDirectory(java.io.File.new("C:\"))
  else
    fc.setCurrentDirectory(java.io.File.new("/usr/bin"))
  end

  success = fc.show_open_dialog(nil)
  if success == Java::javax::swing::JFileChooser::APPROVE_OPTION
    return Pathname.new(fc.get_selected_file.get_absolute_path)
  else
    nil
  end
end

puts "The user picked: #{pickEditor}"

# EOF
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