IDEA 设置 Java 版本
1. 设置模块语言级别
File->Project Structure->Project Settings->Modules->Language Level
2. 设置编译语言级别
File->Settings->Build, Execution, Deployment->Compiler->Java Compiler->Target bytecode version
截图
File->Project Structure->Project Settings->Modules->Language Level
File->Settings->Build, Execution, Deployment->Compiler->Java Compiler->Target bytecode version
截图