![]() ![]() ![]() An interface can extend only other Java Interfaces, whereas an abstract class can extend other class and implement interface also.An abstract class is used to define a contract, method implementations for the subclass, whereas an interface is used to define a contract for subclasses.An abstract class can have constructors, whereas an interface doesn’t have a constructor.An abstract class and its methods can be created by keyword “abstract”, whereas interface keyword is used to create interface but not methods.An abstract class can have different variables like static, final, non-final, non-static, public, private etc., whereas Interface can have only public, static and final variables.An interface can have only abstract methods, whereas an abstract class can have both abstract and normal classes.In an abstract class, we need to declare methods using the “abstract” keyword, whereas, in the interface, we can declare methods with or without the “abstract” keyword.An abstract class extends another abstract or normal class, whereas an interface can extend only another Java interface.An abstract class extends only one normal class or abstract class at a time, whereas an interface can extend any number of interfaces at a time.Interface used to achieve complete abstraction, whereas an abstract class can achieve partial abstraction.An interface can be used to achieve multiple inheritances and loose coupling, which we can’t able to achieve by the abstract class.In Java, we can have an abstract class without an abstract keyword, but those classes can’t be instantiated, only inherited, and can have final methods also. ![]() It can have constructors, and the abstract class is called when an inherited class instance is created. We can use a child’s object (which is newly created) to call abstract and normal methods. we can’t create an object for it but can have references to abstract class by creating another class that extends the abstract class and provides the implementation of methods. Abstract class can’t be instantiated, i.e. An Abstract class can have abstract (method without a body) and concrete methods (method with a body), unlike a normal class. ![]() AbstractĪ class that is declared by the keyword “abstract” is called an abstract class. To declare an interface, we need to use the interface keyword, and to implement the interface we need to use the implements keyword. We can’t extend the interface to more than one class as Java doesn’t allow it. In general, a class that implements an interface needs to define all methods declared in an interface if it’s doesn’t then the class must be declared abstract. So they need to be implemented by the class before trying to access them. An Interface is used to provide full abstraction as methods in interfaces do not have a body. Web development, programming languages, Software testing & others InterfaceĪn Interface is like a class, but it is not, which can have methods and variables as a class but methods declared in an interface are abstract by default. Interface can’t have static methods, main method or constructor.Ībstract class doesn’t support multiple inheritance.Start Your Free Software Development Course Java interface should be implemented using keyword “implements” Ībstract class can have static methods, main method and constructor. The interface keyword is used to declare interface.Ī Java abstract class should be extended using keyword “extends”. The abstract keyword is used to declare abstract class. Java interface is required when we want implement contract between service and client. Members of a Java interface are public by default.Īn abstract class required when we want some default behavior in our project as like in DAO layer there are some common behavior save object, delete object etc. Variables declared in a Java interface is by default final.Ī Java abstract class can have the any flavors of class members like private, abstract. we can say it can have abstract and non-abstract methods.īy default all methods of interface are abstract.Īn abstract class may contain non-final variables. This is very common question in core java interview for entry level programmer so let’s discuss some important point of difference as below: Difference between interfaces and abstract classes abstract classĪbstract class may not be contain abstarct method or may be contain. ![]()
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