Login window with MigLayout in JRuby

gistfile1.rb

# Using MigLayout as frankly Javax Swing without a decent GUI
# tool is really a nightmare
# One has to download the MigLayout jar from its site
# then put it inside the jruby/lib folder

require 'java'

# For rvm users => allow to just run jruby frontend.rb
# provided that a .rvmrc has been created in the directory where
# frontend.rb is located.
# If not, use rvm_path the same way as jruby_path with ENV['rvm_path']
# One could also without rvm define a jruby_path in his environment.
# And without that it should be run as j
# ruby -J-cp /pathtojruby/lib/miglayout-4.0.jar frontend.rb

jruby_path = File.expand_path(ENV['MY_RUBY_HOME'] || '~/.rvm/rubies/jruby-1.7.0.preview2')
require "#{jruby_path}/lib/miglayout-4.0.jar"

# Loading the classes using ruby, much less tiring than listing all the imports
swingClasses = %w(JFrame JPanel
                  BorderFactory JLabel JTextField JPasswordField
                  JButton SwingConstants)
awtClasses = %w(Color EventQueue event.ActionListener event.ActionEvent)
swingClasses.each {|swc| java_import "javax.swing.#{swc}"}
awtClasses.each {|awc| java_import "java.awt.#{awc}"}

java_import 'net.miginfocom.swing.MigLayout'

# Far better with reopening JButton and passing a block with parameters
class JButton
  def on_clicked login,password,message, &block
    add_action_listener do |e|
      block.call
    end
  end
end

# Not sure if it is not dangerous here,
# maybe should be in the block passed to JButton
class JPasswordField
  def get_as_string
    clear_password= ''
    get_password.each { |ch| clear_password << ch }
    return clear_password
  end
end

# I confess I install Eclipse to Get WindowBuilder and  write first
# the code in Java, and then manually translate it into JRuby

class MyFrontEnd < JFrame
  def initialize(title)
    super(title)

    set_default_close_operation JFrame::EXIT_ON_CLOSE

    contentPane = JPanel.new
    contentPane.border = BorderFactory.createEmptyBorder 5,5,5,5
    set_content_pane contentPane
    contentPane.layout = MigLayout.new "",
      "[93.00:89.00][][137.00][128.00:128.00][122.00]", "[25.00][][36.00][:25.00:29.00][38.00,center]"
      #{#}"[93.00:89.00][][137.00][128.00:128.00][122.00]", "[25.00][][36.00][:25.00:29.00][38.00,center]"

    frameTitle = JLabel.new 'A Simple Application'
    frameTitle.horizontal_alignment = SwingConstants::CENTER
    contentPane.add frameTitle, 'cell 2 0 2 1,alignx center,aligny top'

    loginLabel = JLabel.new 'Loginid'
    contentPane.add loginLabel, 'cell 0 1'

    loginField = JTextField.new
    contentPane.add loginField, 'cell 3 1'
    loginField.columns = 10

    passwordLabel = JLabel.new 'Password'
    contentPane.add passwordLabel, 'cell 0 2'

    passwordField = JPasswordField.new
    passwordField.columns = 10
    contentPane.add passwordField, 'cell 3 2'

    messageLabel = JLabel.new 'Message'
    contentPane.add messageLabel, 'cell 0 3'

    messageField = JTextField.new
    messageField.columns = 25
    messageField.opaque = true
    messageField.background = Java::Java.awt.Color.new 237, 237, 237
    messageField.border = BorderFactory.createCompoundBorder \
          BorderFactory.createLineBorder(Color.new(133, 170, 220), 2),
          BorderFactory.createEmptyBorder(2, 5, 2, 5)
    messageField.enabled = false
    messageField.editable = false
    messageField.focusable = false
    contentPane.add messageField, 'cell 3 3 2 1'

    submitButton = JButton.new 'Submit'
    submitButton.on_clicked(loginField, passwordField, messageField) {
      # Tribute to Satish who makes me work hard :-)
      if loginField.get_text == "Satish" && passwordField.get_as_string == "Talim"
        messageField.set_text "Congratulations, you are now logged in!"
      else
        messageField.set_text "Sorry, incorrect login or password"
      end
    }
    contentPane.add submitButton, 'flowx,cell 2 4,alignx right,aligny bottom'

    refreshButton = JButton.new 'Refresh'
    refreshButton.on_clicked(loginField, passwordField, messageField) {
      loginField.set_text ""
      passwordField.set_text ""
      messageField.set_text ""
    }
    contentPane.add refreshButton, 'cell 3 4,alignx left,aligny bottom'
    pack
    set_visible true
  end
end

mb = MyFrontEnd.new('Assignment 1')

Maybe use a module...

module Credentialable
  class Credentials
    attr_reader :loginField, :passwordField, :messageField
  # use @@user.loginField for example
    def initialize
      @loginField = JTextField.new
      @passwordField = JPasswordField.new
      @messageField = JTextField.new
    end
  end
end

include Credentialable
@@user = Credentials.new

Alternatively, can you pass the user object to your MyFrontEnd?