Always Keep Data Private
这都是过来人的经验呐！如果封装的好，那么后续的修改维护都会方便很多
Always Initialize Data
Don’t Use too Many Basic Types in a Class
用一个类来替代各种各样的变量能增强程序的可读性
Not All Fields Need Individual Field Accessors and Mutators
Break up Classes that Have too Many Responsibilities
有点模块化编程的意思
Make the Names of Your Classes and Methods Reflect Their Responsibilities
对于 class，最好是 形容词/动名词+名词
对于 accessor，最好是 get+什么东西
对于 mutators，最好是 set+什么东西
Prefer Immutable Classes
问题主要在于多线程，由于并发的缘故可能导致修改不正确