Question I hope to be answered

Hello all of you ,

I need your help please . In fact, I had three different questions which are :
First of all, what is different between interface and polymorphism in java! and which one is better to use in the application?
Secondly, what is different between interface and abstract class! I m kindly confused seriously?
Thirdly, what is the easiest way to use JDBC in java for my application using NetBeans?

Please could you help me with this. Thanks all of you guys



Thanks alot for your patient