This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
You only “need” to mark local variables or parameters final when they are used inside an anonymous or local class.
It is probably a good code convention to mark them final to remind yourself they are not changed, but, Stephan is right; you can change local variables if you wish. Changing parameters might cause confusion, but that does not merit a rule.