Conceptual diagram of the Java basics

Introduction

Java is an object-oriented programming language that can compose cross-platform applications. Java technology, with its versatility, efficiency, platform portability and security, is widely used in PCs, data centers, game consoles, science supercomputers, mobile phones, and the Internet, while owning the world's largest developer professional community.

Java is divided into three systems, namely Javase (J2se,java2 Platform standard Edition, Standards edition), Java EE (J2ee,java 2 Platform, Enterprise Edition, Corporate Edition), Java ME (J2me,java 2 Platform micro Edition, mini version).

To learn Java, you must first understand javase to lay the groundwork, this article javase the latest version of JavaSE8 for the introduction of the object, explaining the concept of javase composition. The topics in this article are as follows:

• 1, the composition concept diagram is intuitive
• 2. Detailed concept of composition
• • 2.1. JVM
  • 2.1. JRE
  • 2.3. JDK
  • 2.4. Java language
• 3. Summary

1, the composition concept diagram is intuitive

The following diagram shows the composition concept of JavaSE8:

It can be seen clearly that JavaSE8 consists of 4 parts: JVM, JRE, JDK, and Java language. The second section will cover these 4 sections in detail.

2. Detailed concept of composition

Now we pick up the scalpel to dissect the pieces. Below we explain the parts from the bottom up.

2.1. JVM(Java Virtual machine java VM)

The JVM can be understood to be a virtual computer, with the basic computing method of the computer, it is responsible for the Java program generated bytecode files are interpreted as the machine instructions on the specific system platform. Let specific platforms such as Windows run these Java programs.

2.2, JRE(Java Runtime Environment Java Run environment)

The JRE includes the Java Virtual machine (JVM Java VM) and the core class library required by the Java program, and if you want to run a well-developed Java program, you only need to install the JRE on your computer.

2.3, JDK(Java Development Kit Java Development Kit)

The JDK is available to Java developers, which includes Java development tools and the JRE. So with the JDK installed, you don't have to install the JRE separately. The development tools include the build tool (Javac.exe) packaging Tool (Jar.exe), and so on.

2.4, Java language

The Java language is an object-oriented, high-level language that runs on a special platform, a Java virtual machine. Java is a simple, object-oriented, distributed, interpretive, robust, secure, structured-neutral, portable, high performance, multi-threaded static language.

3. Summary

In simple terms: Java programs developed using the JDK are delivered to the JRE to run.
Three relations:
JVM: A machine instruction that converts a bytecode file into a specific system platform.
The core class library of the Jre:jvm+java language. Development tools for Jdk:jre+java.

Conceptual diagram of the Java basics