I had a hole of little more than three weeks in between projects and wanted to do something useful such as passing a cetification exam.
So I read Servlets & JSP ²nd edition as well as SCWCD study companion ²nd edition. (this in 15 days time, nine to five) JSP, tags, EL, filters, security... all was new to me.
The day before the exam I studied from dusk till dawn, trying to remember the little details.
There were still some things that weren't perfectly clear to me, but nevertheless I passed it with a score of 76%.
I'm glad I passed it, but at the same time I feel that it was a bit short to really become a true expert on the topic.
But hey, it's not that when you pass an exam, that there's no more reason in getting better in it! I've got the books...
Oracle Java SE6 Certified Programmer
Oracle Java EE5 Certified Web Component Developer
Pivotal Certified Spring Professional