Please visit the following links:

http://www.roseindia.net/java/beginners/oop-in-java.shtml

http://www.roseindia.net/java/learn-java-in-a-day/oops.shtml

Abstraction:Providing necessary attributes and operations ,hiding the internal things is called Abstraction.Example is a CAR will a have parts like engine,tire....But the user of the car(driver) know how to drive the car.But he doesn't know any knowledge of these parts.

Inheritance:Process of creating new class from already existing class is called inheritance.new class is called 'sub class','child class','derived class' and existing class is called 'super class','base class','parent class'. Example:Parents and children relationship

Encapsulation:binding the data and functions into a single component is Encapsulation. Ex:Java class is combination of variables and methods. Ex2:medicine capsules

Polymorphism: Poly means 'many' and morphism means 'forms'.It is a Greek word.To take more than one form is called Polymorphism. Ex:The person in home act as a son or husband same person in office act as a employee ,, ,, in society act as citizen.