编译环境改为1.8,改三个地方
- 1.Project Structure中的Project SDK选择1.8,Project language level选择8
- 2.Project Structure中Modules,选择language level为8
- 3.setting中的java compiler,project bytecode version和Target bytecode version 选择1.8
1.Project Structure中的Project SDK选择1.8,Project language level选择8

2.Project Structure中Modules,选择language level为8

3.setting中的java compiler,project bytecode version和Target bytecode version 选择1.8

其他方法:
Maven配置
org.apache.maven.plugins maven-compiler-plugin 2.3.2 1.8 1.8