what is difference between Abstract class and interface ????

An Abstract Class can contain default Implementation where as an Interface should not contain any implementation at all. An Interface should contain only definitions but no implementation. where as an abstract class can contain abstract and non-abstract methods. When a class inherits from an abstract the derived class must implement all the abstract methods declared in the base class. an abstract class can inherit from another non-abstract class.

java books

http://www.informit.com/library/library.aspx?b=STY_Java2_24hours

what is java

Java is a programming language ,It is Object Oriented Programming language, And the specality of java is an PLATFORM-INDEPENDENT ,developed by SUN-MICEROsystems,
the father of java is "

James Gosling".