java 为什么在运行时检查@Nonnull 注释？
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Why @Nonnull annotation checked at runtime?
提问by Dmitry
I have a function with following signature
我有一个带有以下签名的函数
public static String myFunction(@Nonnull String param)
When I call it with param as null, I get the following exception:
当我使用 param 为 null 调用它时，出现以下异常：
Caused by: java.lang.IllegalArgumentException: Argument for @Nonnull parameter 'param' of com/MyClass.myFunction must not be null
at com.MyClass.$$$reportNull$$##代码##(MyClass.java)
javax.annotation.Nonnull supposed not to be checked at runtime.
javax.annotation.Nonnull 不应该在运行时检查。
Who actually throws the exception and why?
谁实际上抛出了异常，为什么？
P.S. I run Tomcat server in debug mode from IntelliJ IDEA 2016.3 with Oracle JDK 1.8.0_102
PS我使用Oracle JDK 1.8.0_102从IntelliJ IDEA 2016.3以调试模式运行Tomcat服务器
回答by yole
When you compile your project in IntelliJ IDEA, it instruments the bytecode of compiled classes to add runtime checks for various flavors of @Nonnullannotations. This behavior is controlled by the option:
当您在 IntelliJ IDEA 中编译您的项目时，它会检测已编译类的字节码，以便为各种@Nonnull注释添加运行时检查。此行为由选项控制：
Settings | Build, Execution, Deployment | Compiler | [x] Add runtime assertions for not-null-annotated methods and parameters.
设置 | 构建、执行、部署 | 编译器 | [x] 为非空注释的方法和参数添加运行时断言。
