Raw Block

My recent post "JRuby Can Save Swing" generated a bit of discussion around the blogosphere. A few blogs replied, and a lot of good points were made. I was a little disappointed that most of the rebuttal I got was in regard to Joshua Marinachi’s original 2003 post and his list of why Swing sucks, and not to the points I raised about the potential that a new framework based in JRuby could provide. I guess that is blogging-101 - put your payload at the front and minimize the lead up.

From the original post, my dream list for a higher level GUI framework for Swing are

• Structured application layout
• Proper decoupling of model from view
• Automatic binding of model to view without glue code
• View logic code separated from layout markup
• Application lifecycle support
• Minimize the amount of code
• Minimize complexity
• Testable
• Make the Right way of doing things the path of least resistance

JRuby cannot save Swing

pinderkent replied with the idea that Swing is beyond saving, and nothing JRuby or anything else can do can save it. I don’t think Swing is at that point. I think in the last few years Swing has turned a corner an is improving with each release (5 was great, 6 is good as well). My initial article title was intentionally a little inflammatory. I don’t actually think Swing “needs” saving. All the same I think there are some areas that can be helped out.

Swing is slow?

Pinderkent then trots out the tired “Swing is slow argument”. This may have been the case… on a Pentium 2 back in 1998. This has not been true for a long time. Swing itself is more efficient, and CPUs are faster. It just isn’t an issue anymore. The pinderkent says they haven’t actually done any profiling. Nuff said.

Danno Ferrin responded to pinderkent and makes the point in another follow up:

"The stock answer to this is always true: "bad programmers abuse the Event Dispatch Thread." Seriously, whenever anyone wants to start programming Swing someone else needs to get a stick and beat them until they write in blood the oath "I will not do data processing in the Event Dispatch Thread." "

Which is exactly my experience. It is possible to create snappy, responsive Swing apps - but the moment anyone does some heavy processing, or a database call, or file operation from a listener - you’re wading through mud. Maybe that’s an extra point for my framework wish list: "Makes using worker threads instead of the EDT the path of least resistance for heavy operations."

Groovy Can Save Swing

Danno Ferrin’s main point is that Groovy would be a more suitable layer for Swing than JRuby.

The argument is that Groovy is closer to Java and it would mean developers wouldn’t have to learn all of Ruby’s weird syntax and "ugly PERLisms". Maybe. I have to admit I haven’t had any exposure to Groovy. Ruby isn’t difficult to pick up though, and the syntax arguments are really just a matter of opinion. What I believe makes Ruby ideal as a DSL/wrapper API layer is the level of meta-programming Ruby affords to achieve things that are impossible in Java. I’m talking about things like stupidly easy model-view binding. In ruby you can do something like

model = Person.new('Julian Doherty', 'julian@example.com')

name_label = JLabel.new
name_label.bind_to model, :name

email_field = JTextField.new
email_field.bind_to model, :email

And have the text label and field bound to the model so changes on either side are automatically replicated to each other - all without a single line of event listener glue code. I’ve got some sample code showing this working, and will write something about it soonish. I’ve already written about Transparent Property Change Listeners for Ruby bean-type classes, which shows part of the solution.

I don’t know if Groovy gives you that or not. If it does, great. If not, then that’s a reason to consider JRuby over Groovy.

Homework for me: grok Groovy so I’m better informed on this

Does Swing Need Saving?

Daniel Spiewak posted a rebuttal of Joshua Marinachi’s original “why Swing Sucks posts” that I reposted.

It’s a good post and A lot of his points were on the money (which I won’t discuss much except to say I agree): his discussion of layout managers (GroupLayout etc); native feature integration; and Swing’s bad perception from a troubled past.

A few didn’t quite stack up with me though.

Ruby is the same amount of work as Java?

In arguing that Swing GUIs are just as easy to construct in Java as JRuby, Daniel Spiewak provides an overly simple UI consisting of a label and three buttons - implemented both in JRuby and then Java. The two versions are almost identical, and there is no difference in code complexity or length (how surprising!). Problem is, the examples didn’t have anything done in the real world: no advanced layout, no event handling, no model/view interaction, no validation. It’s a weak straw man argument that really doesn’t tell us anything.

A more interesting example would be to compare a straight Java implementation of a reasonably complex application (including any cool 3rd party libraries) and a JRuby framework based implementation (using all the Ruby black magic possible). My guess is that the JRuby version would come out ahead.

Swing isn’t slow to build?

Daniel Spiewak then says that a reasonably complex UI could be coded in a few hours by a himself, and half that by Romain Guy.

So what?

It’s a pretty arbitrary metric which still doesn’t say anything. What would be interesting again is the difference between Java and a JRuby framework implementation. Maybe JRuby only takes one hour or maybe it takes five? I don’t know. My guess though is that again it would take far less code, would be easier to test, and would be finished quicker in JRuby by the same developer.

Separate markup layout of view is bad?

Daniel Spiewak also questioned whether using XML to store the GUI config is a good idea. I AGREE! XML is horrible and is abused in Java land (I actually said to use YAML in the original post as it is a bit more human friendly). I wasn’t advocating to use XML/YAML to create the whole GUI - just as a mark up to separate the layout from the component instantiation and move layout out of the view code.

My opinion is that code is good for expressing view logic, but not visual layout. That would be better served by some separate markup.

Swing apps are hard to maintain because of bad developers?

One of the main beefs I’ve got with Java/Swing and one that Daniel Spiewak’s touched on, is the difficulty maintainability of Swing apps. He says that main problem with bad Swing apps is that bad developers don’t do a good job - which I totally agree with! It is definitely possible to structure a good Swing app and develop it in a nice clean way, but to do things the right way is a lot of work. The path of least resistance is to take short cuts and just get it done (especially when deadlines are pressing). Yes, Swing has a nice MVC architecture, and best practice says you should build apps that way - but it’s just too much work to use properly in the real world.

I liked a quote from one of Danno Ferrin’s other related blog posts “Groovy, Verbosity, and Swing:

“I think that the greatest problem with the swing APIs are not that they are too complex or too poorly explained. The biggest problem I see is that to do simple things the correct way, it can get quite verbose. Kind of like reliable file I/O, but you get far fewer urgent-1 bug in the GUI than in core I/O routines. Perhaps the best thing isn’t to change the Swing APIs, but to add more syntactic sugar.”

Which is exactly what I was trying to get at with my original post. Swing is a great low level API, and provides the developer with a lot of power to do things. Problem is, the path of least resistance is to produce ugly crud that barely works. Where as something like Rails provides a path of least resistance that results in elegant and well structured code.

Every API acts like a multiplier for developer productivity, and has a response curve of varying slope. Some frameworks make good developers amazing while making mediocre developers passable (Rails springs to mind).

Swing seems to do the opposite though. It makes amazing developer’s work merely good, and mediocre developer’s work unacceptable.

Comments on the original post

Why not Eclipse/NetBeans RCP? What about JSR-296 application framework?

Steve said…

I agree with the sentiment, but not to craft yet another solution.

Why don’t we just call this Eclipse or NetBeans RCP?

Really these things have been done, what we lack is people understanding and using them.

There is a JSR on the table for a Swing framework too - JSR-296, this will help quite a bit.

Good points. I have to plead ignorance on exactly what the Eclipse and NetBeans RCPs provide (more homework for me!). However one of the benefits of JRuby is all the meta-programming that is either impossible or overly verbose in Java. They also both smack of the whole Big Java philosophy (XML configuration and all!) which a lot of developers are getting disillusioned with. As for JSR-296 - it’s definitely a good thing, and any framework should build on top of it, not replace it.

Groovy SwingBuilder?

Anonymous said…

Groovy already has a SwingBuilder, which I suppose you could duplicate in Ruby… but most of these are done arleady.

Good point, but layout is just a small piece of the puzzle. My understanding is that SwingBuilder just helps you with the layout and still leaves everything else (binding, application structure etc) to you to implement

So… now what?

I’m keen to experiment with some of my original ideas from JRuby Can Save Swing. I’m trying to pick a small/medium, low-risk project to roll a basic JRuby Swing framework for and see how it goes. So far I’ve been doing a few little demos that show off some of the basic concepts (will post some examples soon!). It’s definitely promising, but it’s hard to tell from anything that small.

Stay tuned