关闭资源：
try-with-resource:https://juejin.im/entry/57f73e81bf22ec00647dacd0
内部类和闭包：https://www.jianshu.com/p/f55b11a4cec2
Java语法糖系列一：可变长度参数和foreach循环
http://www.jianshu.com/p/628568f94ef8
Java语法糖系列二：自动装箱/拆箱和条件编译
http://www.jianshu.com/p/946b3c4a5db6
Java语法糖系列三：泛型与类型擦除
http://www.jianshu.com/p/4de08deb6ba4
Java语法糖系列四：枚举类型
http://www.jianshu.com/p/ae09363fe734
Java语法糖系列五：内部类和闭包
http://www.jianshu.com/p/f55b11a4cec2
来源：https://blog.csdn.net/qq_21574693/article/details/98727269