what is the difference between abstract class and interface?
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The key technical differences between an abstract class and an interface are: Abstract classes can have constants, members, method stubs (methods without a body) and defined methods, whereas interfaces can only have constants and methods stubs.
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A class is a blueprint from which we can create objects that share the same configuration - properties and methods. An interface is a group of related properties and methods that describe an object, but neither provides implementation nor initialisation for them.
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The abstraction technique aims to separate the implementation details of a class from its behavior. Abstraction and encapsulation are complementary concepts. On the one hand, abstraction focuses on the behavior of an object. On the other hand, encapsulation focuses on the implementation of an object's behavior.
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Interface is collection of ONLY abstract methods and final fields. There is no multiple inheritance in Java. Interfaces can be used to achieve multiple inheritance in Java. One Strong point of Inheritance is that We can use the code of base class in derived class without writing it again.
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Main difference is methods of a Java interface are implicitly abstract and cannot have implementations. A Java abstract class can have instance methods that implements a default behavior. ... A Java class can implement multiple interfaces but it can extend only one abstract class.
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Interfaces cannot be instantiated, but rather are implemented. A class that implements an interface must implement all of the non-default methods described in the interface, or be an abstract class. ... Object (the root class of the Java type system); multiple inheritance of classes is not allowed.
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Interface represents the set of operations that a data structure supports. ... Implementation − Implementation provides the internal representation of a data structure. Implementation also provides the definition of the algorithms used in the operations of the data structure.
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The implements keyword is used to implement an interface . The interface keyword is used to declare a special type of class that only contains abstract methods. To access the interface methods, the interface must be "implemented" (kinda like inherited) by another class with the implements keyword (instead of extends ).
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An abstract class can have an abstract method without body and it can have methods with implementation also. ... An abstract class is mostly used to provide a base for subclasses to extend and implement the abstract methods and override or use the implemented methods in abstract class.
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The main difference between abstraction and inheritance is that abstraction allows hiding the internal details and displaying only the functionality to the users, while inheritance allows using properties and methods of an already existing class. Object-Oriented Programming (OOP) is a major programming paradigm.
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Functional interface are is used in a "safe" multiple inheritance. ... A class may extend multiple functional interfaces. Functional interfaces may have only a single abstract method. Functional interfaces may not have fields unlike C++ abstract classes.
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Following are the notable differences between non-static methods and abstract methods. These methods contain a body. You can use normal method directly. You cannot use abstract methods directly, to use them you need to inherit them and provide body to these methods and use them.
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Inheritance is creating a class that derives its feature from an already existing class. On the other hand, polymorphism is an interface that can be defined in multiple forms. Inheritance is implemented on the classes whereas, the polymorphism is implemented on methods/functions.
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An abstract class is declared using abstract modifier. A concrete class is note declared using abstract modifier. An abstract class cannot be directly instantiated using the new keyword. A concrete class can be directly instantiated using the new keyword.
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The main difference is the compiler won't let you instantiate an abstract class, while you could instantiate a base class (which may not make sense). Notice with the variable d we are guaranteed that the abstract methods have been overridden (otherwise the DerivedType class would have a compiler error).
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Delegates and Interfaces are two distinct concepts in C#. Interfaces allow to extend some object's functionality, it's a contract between the interface and the object that implements it, while delegates are just safe callbacks, they are a sort of function pointers.
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The difference between wrapper class and primitive type in Java is that wrapper class is used to convert a primitive type to an object and object back to a primitive type while a primitive type is a predefined data type provided by the Java programming language.