Java Abstract Class Extends Interface

Abstract classes can include abstract methods.

Java abstract class extends interface. With interfaces all fields are automatically public static and final and all methods that you declare or define as default methods are public. Writing an interface is similar to writing a class. 2an interface can not extend inherits any other class abstract class with non abstract methods and pure abstract class abstract class having all abstract methods. The body of the interface method is provided by the implement class.

In addition it can also declare new abstract methods and constants. To access the interface methods the interface must be implemented kinda like inherited by another class with the implements keyword instead of extends. Any class that extends a class with an abstract method must implement that method. To extend an interface you use the extends keyword just as you do in the class definition.

Abstraction is a process of hiding the implementation details and showing only functionality to the user. Note that when a class inherit an interface we use the keyword implements like class x implements a. An interface can have only abstract methods. An abstract class can have both abstract and concrete methods.

An interface can extend any number of interfaces at a time. 1 an interface can extend inherits only another interface. Java 7 for absolute beginners. Along with abstract methods an interface may also contain constants default methods static methods and nested types.

A class implements an interface thereby inheriting the abstract methods of the interface. You cannot instantiate them and they may contain a mix of methods declared with or without an implementation. Method bodies exist only for default methods and static methods. In other way there can be a super interface for an interface but there can not be a superclass for an interface.

Abstract classes are similar to interfaces. Modeling the animal kingdom is a simple example so its not hard to see that mammal should be an abstract class. The hard part is figuring out when a class should be abstract. When interface inherits another interface we use extends keyword as given in example below.

An interface can only extend another interface. However with abstract classes you can declare fields that are not static and final and define public protected and private concrete methods. Concept of inheritance in java an interface extends another interface using the keyword extends. This can be done using the following syntax.