@Nonnull和Objects.requireNonNull有什么区别 [英] What is the difference between @Nonnull and Objects.requireNonNull

问题描述

以下两个代码段之间有什么区别.

What is the difference between following two code snippets.

public Integer getId(@Nonnull SomeObject obj){  
    // do some stuff
    return id;
}

public Integer getId(SomeObject obj){   
    Objects.requireNonNull(SomeObject, "SomeObject is null");
    // do some stuff
    return id;
}

它们之间的显着区别是什么.在这些情况下进行空值检查的正确方法是什么.

What are the significant differences between them. And what is the correct way to do the null-check in these situations.

推荐答案

两者是互补的: @Nonnull 注释记录了 obj 必须为非null的事实，而 Objects.requireNonNull 调用可确保 obj 在运行时不为空.

The two are complementary: @Nonnull annotation documents the fact that obj must be non-null, while Objects.requireNonNull call ensures that obj is non-null at run-time.

您应该将两者结合起来，像这样:

You should combine the two, like this:

public Integer getId(@Nonnull SomeObject obj){   
    Objects.requireNonNull(SomeObject, "SomeObject is null");
    // do some stuff
    return id;
}

@Nonnull 上的相关文档可以找到此处:

Relevant documentation on @Nonnull can be found here:

可选的类型注释不能替代运行时验证

在类型注释之前，描述诸如可空性或范围之类的东西的主要位置在javadoc中.使用Type批注，这种通信以一种编译时验证的方式进入字节码.

Before Type Annotations, the primary location for describing things like nullability or ranges was in the javadoc. With Type annotations, this communication comes into the bytecode in a way for compile-time verification.

您的代码仍应执行运行时验证.

Your code should still perform runtime validation.

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