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.
First, please don't use so much bold. It's like shouting, and it makes your post unpleasant to read.
As for your question, please SearchFirst(←click) and come back with more specific questions after you've done some research if some particular point is not clear. The question has been discussed to death here and on other sites, and has plenty of coverage in tutorials, blogs, and whatnot. There's a good starting point right on this site: https://www.coderanch.com/how-to/java/InterfaceVsAbstractClass