Groovy and SwingBuilder

In my comparison of IronPython, Groovy and JRuby I used a "naked" Swing API to create a GUI application using Groovy. Groovy comes with a nice library called SwingBuilder that simplifies a lot of work with Swing. I couldn't find any documentation for SwingBuilder but the source code is pretty straight-forward. In my opinion, the best thing in the SwingBuilder version is the way you declare that a form has a button:

def frame = swing.frame(defaultCloseOperation: WC.EXIT_ON_CLOSE) {
  button('OK', actionPerformed: click)
}

You can pass a closure to the frame method.
I really like this way. It allows you to create your GUI in a more declarative way.

As was suggested by Martin C. Martin and Dierk Koenig (many thanks!) on the Groovy-user list, the code might look something like the following:

import javax.swing.WindowConstants as WC

click = { event ->
  event.source.text = "Pressed!"
}

def swing = new groovy.swing.SwingBuilder()
def frame = swing.frame(
  size: [200, 200],
  defaultCloseOperation: WC.EXIT_ON_CLOSE,
  title: 'Hello' ) {
     button('OK', actionPerformed: click)
}

frame.show() 

Creating GUI with IronPython, Groovy and JRuby

I was curious what are the differences between the following tools when it comes to creating a GUI desktop application:

• IronPython (with Windows Forms)
  
• Groovy (with Swing)
• JRuby (with Swing)
  

I prepared a simple example for each of them. The application shows a form with one button. This button when clicked changes its own text.

IronPython:
tested with 1.1a1 (1.1) on .NET 2.0.50727.42

• Native windows
  
• Possible to pass parameters in the constructor (form = Form(Text="test"))
• Nice += for event handlers
• As such a simple example it should work with Mono on Linux, however not sure about more complicated ones.
  

import clr
clr.AddReference("System.Windows.Forms")
clr.AddReference("System.Drawing")
from System.Windows.Forms 
import Application, Button, Form
from System.Drawing import Size


form = Form(
    Text="Hello",
    Size=Size(200, 200)
)

button = Button(Text="OK!")

def onClick(event, handler):
    button.Text = "Pressed!"

button.Click += onClick
form.Controls.Add(button)

Application.Run(form)

Groovy:
tested with 1.0-RC-01
(Thanks to Marcin Domański for his help on this example)

• Cross-platform
• Elegant event handlers api (actionPerformed:click)
• Possible to pass parameters in the constructor (as in IronPython)
  

import javax.swing.JFrame
import javax.swing.JButton

def frame = new JFrame(
  title:"Hello",
  size:[200, 200],
  defaultCloseOperation:JFrame.EXIT_ON_CLOSE
)

def click = {
  event -> event.source.text = "Pressed!"
}

def button = new JButton(
  text:"OK!",
  actionPerformed:click
)

frame.add(button)
frame.show()

JRuby
tested with 0.9.2

• Cross-platform

• JRuby allows you to call Java code using the more Ruby-like underscore_method_naming and to refer to JavaBean properties as attributes.
• Event handlers using classes is not nice
  

require 'java'
include_class "javax.swing.JFrame"
include_class "javax.swing.JButton"
include_class "java.awt.event.ActionListener"

frame = JFrame.new("Hello")
frame.set_size(200,200)
frame.defaultCloseOperation = JFrame::EXIT_ON_CLOSE

button = JButton.new("OK!")

class ClickListener < ActionListener
  def actionPerformed(event)
    event.source.text = "Pressed!"
  end
end

button.add_action_listener(ClickListener.new)

frame.add(button)
frame.show

Update: There is a simpler Groovy version with SwingBuilder.