Java Abstract Class Implements Interface

The first thing which puzzles many programmers is the fact that you cannot define any method inside interface it a just declarationby rule all method inside interface must be abstract well this rule is changing in java 8 to allow lambda expressions now interface can have one non abstract method also. Writing an interface is similar to writing a class. When an abstract class implements an interface in the section on interfaces it was noted that a class that implements an interface must implement all of the interfaces methods.
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A class can extend only one abstract class while a class can implement multiple interfaces.

Java abstract class implements interface. It is possible however to define a class that does not implement all of the interfaces methods provided that the class is declared to be abstract. Sample code for interface and abstract class in java. Interface attributes are by default public static and final. Java interface another way to achieve abstraction in java is with interfaces.

Interface methods do not have a body the body is provided by the implement class. Java interfaces are blueprint like class but will have only method declaration. An interface in java has remained a complex topic for many beginners to understand. A class implements an interface thereby inheriting the abstract methods of the interface.

An abstract class permits you to make functionality that subclasses can implement or override whereas an interface only permits you to state functionality but not to implement it. An interface is a blueprint used to implement a class. This tutorial will explain you the significance of both interface and abstract classes in simple terms. Interface methods are by default abstract and public.

But java abstract class will have abstract methods and concrete methods. Along with abstract methods an interface may also contain constants default methods static methods and nested types. However the interface offers full abstraction in java something that abstract classes cannot do. Method bodies exist only for default methods and static methods.

It is a collection of abstract methods and contains no concrete methods unlike abstract class. An interface is a completely abstract class that is used to group related methods with empty bodies. On implementation of an interface you must override all of its methods. But java abstract class will have abstract methods and concrete methods.