On his blog today Jani Hartikainen looks at his experience learning Wicket (a Java application framework) from the perspective of a PHP developer.
My starting point with Wicket was basically zero, at least Java-wise: I had never used any Java web app framework, so I didn't really know what to expect. Since as I said I've mostly used PHP and Python, I assumed the program flow would be something like in them. Of course, this was a completely wrong assumption.
He includes one specific example - handling a form submission. In PHP you work with the POSTed values and do something (insert into a database, email, etc) but with Wicket you really just display the form again - with a few other bits of configuration of course. You worry more about what's in the form instead of how to handle the results. He notes that it's a lot like working with a desktop application environment and recommends it as "an interesting way to do things".