说明：  Java语言程序设计教程:$ Sun公司这样形容自己的Java语言:它是一种简单、面向对象、分布式、解释型、稳定、安全、结构中立、易移植、高性能、多线程的动态语言
(Java Programming Language Guide: $ Sun described his company' s Java language: it is a simple, object-oriented, distributed, interpreted, stable, secure, architecture neutral, easy to transplant, high-performance, multi-threaded dynamic language)