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Probably the most commercially important recent object-oriented languages are Java, developed by Sun Microsystems, as well as C# and Visual Basic.NET (VB.NET), both designed for Microsoft's .NET platform. Each of these two frameworks shows, in its way, the benefit of using OOP by creating an abstraction from implementation.
An interface in the Java programming language is an abstract type that is used to declare a behavior that classes must implement. They are similar to protocols.Interfaces are declared using the interface keyword, and may only contain method signature and constant declarations (variable declarations that are declared to be both static and final).
The level of abstraction included in a programming language can influence its overall usability. The Cognitive dimensions framework includes the concept of abstraction gradient in a formalism. This framework allows the designer of a programming language to study the trade-offs between abstraction and other characteristics of the design, and how ...
For example, in Java, the Comparable interface specifies a method compareTo() which implementing classes must implement. This means that a sorting method, for example, can sort a collection of any objects of types which implement the Comparable interface, without having to know anything about the inner nature of the class (except that two of ...
The abstraction principle is mentioned in several books. Some of these, together with the formulation if it is succinct, are listed below. Alfred John Cole, Ronald Morrison (1982) An introduction to programming with S-algol: "[Abstraction] when applied to language design is to define all the semantically meaningful syntactic categories in the language and allow an abstraction over them".
An example of the application of marker interfaces from the Java programming language is the Serializable interface: package java.io ; public interface Serializable { } A class implements this interface to indicate that its non- transient data members can be written to an ObjectOutputStream .
Modern object-oriented languages, such as C++ and Java, support a form of abstract data types. When a class is used as a type, it is an abstract type that refers to a hidden representation. In this model, an ADT is typically implemented as a class, and each instance of the ADT is usually an object of that class.
The abstract superclass of all metaclasses is Class, which describes the general nature of classes. The superclass hierarchy for metaclasses parallels that for classes, except for class Object. ALL metaclasses are subclasses of Class, therefore: Object class superclass == Class. Like conjoined twins, classes and metaclasses are born together.