erm.. you should actually learn the language first.. it's hard to give a presentation on something you don't know much about
talk about Object Orientation

and use java as an example, you should also explore smalltalk, as it's one of the earliest and purest example of Object oriented language.. you can try compare and contrast the two..
talk about it's adventages.. such as it's huge library of useful functions, and it's relative complete swing package

get some background on C++, so you know what java is designed to improve
disadventages: it's verbose syntax (there are people who love it, but most people are lazy

), research a bit on ruby/python/lisp, you'll understand alot of it's disadventage..
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develop with: SBCL + emacs for lisp, Anjuta IDE +gcc for c, SPE for python..
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