This week's giveaway is in the EJB and other Java EE Technologies forum. We're giving away four copies of EJB 3 in Action and have Debu Panda, Reza Rahman, Ryan Cuprak, and Michael Remijan on-line! See this thread for details.
Please read before you get to the code. So that you understand the basics before you try to come up with an example or code.
As the example you have given we would not need map reduce directly,
you can make an example out of it however for your understanding, however it will be much more complex compared to wordcount example