What does the API of JAVA mean?

API (Application Programming Interface) is an application programming interface, which is some predefined functions or an agreement to connect different components of a software system.

Application programming interface, also called application programming interface, is a set of definitions, programs and protocols, and communication between computer software is realized through API interface. One of the main functions of API is to provide a general function set. API is also a middleware, which provides data sharing for various platforms.

In programming practice, the design of programming interface should first make the responsibilities of software system reasonably divided. Good interface design can reduce the interdependence of all parts of the system, improve the cohesion of the constituent units and reduce the coupling between the constituent units, thus improving the maintainability and expansibility of the system.

Extended data:

Functions of API interface:

Java API class file used by the class file of the virtual machine loader when running a Java program. All loaded class files (including those extracted from applications and Java API) and all loaded dynamic libraries (including local methods) * * * together constitute the whole program running on the Java virtual machine.

Before a platform can support Java programs, the functions of API must be clearly realized on this specific platform. To access local resources on the host, the Java API calls local methods. Because Java API class files call local methods, Java programs don't need to call them again.

In this way, Java API class files provide a platform-independent standard interface Java program for the underlying host. For Java programs, regardless of the internal platform, Java API will have the same performance and predictable behavior.

It is precisely because Java virtual machine and Java API are explicitly implemented on each specific host platform that Java programs themselves can become platform-independent programs.

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