Some code to learn Java basics, including some basic class library (system class, common class, time, re and other exercises), Java collection operation, generic operation, annotation exercise, output output stream exercise, NIO,AIO exercise, multithreading exercise, network programming exercise, class loading mechanism and reflection exercise 一些练习java基础的代码，包括一些基础类库（系统类，常用类，时间，正则等练习的操作）、Java集合的操作，泛型的操作，注解的练习，输出输出流的练习，NIO,AIO的练习，多线程的练习，网络编程的练习，类加载机制和反射的练习