说明：  Java是一门面向对象编程语言，不仅吸收了C++语言的各种优点，还摒弃了C++里难以理解的多继承、指针等概念，因此Java语言具有功能强大和简单易用两个特征。Java语言作为静态面向对象编程语言的代表，极好地实现了面向对象理论，允许程序员以优雅的思维方式进行复杂的编程。Java具有简单性、面向对象、分布式、健壮性、安全性、平台独立与可移植性、多线程、动态性等特点。Java可以编写桌面应用程序、Web应用程序、分布式系统和嵌入式系统应用程序等。本文档讲解Java 12基础语法、虚拟机和常用类库参考和实例大全。
(Java is an object-oriented programming language. It not only absorbs the advantages of C + + language, but also discards the concepts of multi inheritance and pointer which are difficult to understand in C + +. Therefore, Java language has two characteristics: powerful function and easy to use. Java language, as the representative of static object-oriented programming language, perfectly implements the object-oriented theory and allows programmers to carry out complex programming with elegant thinking mode. Java has the characteristics of simplicity, object-oriented, distributed, robust, security, platform independence and portability, multithreading, dynamic and so on. Java can write desktop applications, web applications, distributed systems and embedded system applications. This document explains Java 12 basic syntax, virtual machine and common class library references and examples.)