ABAP classes

Hello,

I need to do some work on ABAP classes which I have never done before. therefore, I have a couple of questions which I would appreciate if anyone could help me with:

First, what is the difference between all these classes compare to the traditional abap code.

Second, are these classes similar to the classes in JAVA?

Thirdly, is there any good place on the internet that offer some good introductory material on the topic?

Thanks a lot!

Regards,

Anyi