检查一下几个地方的jdk版本是否一致： 这里建议全部使用: 8-Lambdas,type annotations etc.
1. File -> Project Structure -> Project Settings 2.File -> Project Structure -> Module Settings -> Sources: Language Level 3.File -> Project Structure -> Module Settings -> Tab: Dependencies: Module SDK 4.File -> Settings -> Compiler -> Java Compiler -> Target bytecode version
