Java Origin, Development, features, working methods, composition of development systems, technical applications, java technical applications

Java Origin, Development, features, working methods, composition of development systems, technical applications, java technical applications

1. Origin of java

Oak (poor portability) ------> Java (platform portability not fixed)

2. Java Development

Originator: Java1.0

Development: Java2 JavaSE: java platform Standard Edition

JavaME: Micro version

JavaEE: Enterprise Edition

Start: sun Company ---- later: Oracle Company

3. Java features

1) Object-oriented:Remove the complexity of C and C ++

2) Portability:JVM (Java Virtual Machine) implements program portability

3) Robustness:Early static and dynamic checks are provided to eliminate incorrect conditions and remove pointers.

4) distributed:Java provides some class libraries for network programming, so you can easily use class libraries to process TCP/IP protocols.

5) multithreading:It can be understood as a lightweight process.

4. How Java works

Java source file (. java)--- Compiler compilation --->Bytecode file (. class)--- Classloader loading --->Java Virtual Machine (JVM)--- Resolution --->Operating System(Execution)

5. Composition of the Java Development System

1) Java Virtual Machine (JVM ):Specify the set, register, stack, spam processor, and method area.

　　　　　　　　　Three regions: local variable region, execution environment region, and operand region.

2) Class Library: Java standard class library (officially provided and can be used directly)

Developer's own class (self-import)

3) package:Effectively organize code and manage code structures. The essence is to use folders.

4) JRE: Runtime Environment (Java Runtime Environment)

5) JDK: Java Development Kit, Java Development Kit

6. Java Technology Application

JavaME:At present, the market share is small, and IOS and Android are the mainstream

JavaSE:Standard Edition for programming desktop software

JavaEE:Provides a complete set of solutions for enterprise-level development,JavaWeb