摘要：
# Packages Definition: A package is a grouping of related types providing access protection and name space management. Note that types refers to **cla 阅读全文
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# 注解 注解的作用： - Information for the compiler — Annotations can be used by the compiler to detect errors or suppress warnings. - Compile-time and deploym 阅读全文
摘要：
# Lambda Expression 有了Lambda Expression，就不用再写anonymous classes。 写Lambda，首先要找到它的类型。 There is a restriction on the type of a lambda expression: it has t 阅读全文