IntelliJ 空检查警告 [英] IntelliJ null check warnings

问题描述

我经常有这样的代码:

protected @Nullable Value value;

public boolean hasValue() { return value != null; }

问题在于，当我像这样进行空检查时:

the problem with this is that when I do null checks like so:

if (!hasValue()) throw...
return value.toString();

然后 IntelliJ 会警告我可能的 NPE

then IntelliJ will warn me about a possible NPE

而

if (value != null) throw...
return value.toString();

避免此警告.

有没有办法装饰我的 hasValue() 方法，以便 IntelliJ 知道它执行空检查?并且不会显示警告?

is there a way to decorate my hasValue() method so that IntelliJ knows it does a null check? and won't display the warning?

推荐答案

Intellij-Jetbrains 是非常聪明的 IDE，它本身会为您提供解决许多问题的方法.

Intellij-Jetbrains is very clever IDE and itself suggests you way for solving many problems.

看下面的截图.它建议了您消除此警告的五种方法:

Look at screenshot below. It suggests your five ways for removing this warning:

1) 添加 assert value != null;

2) 用 return value != null 替换 return 语句?value.toString() : null;

3) 用

    if (value != null) {
        return value.toString();
    }

4) 通过添加注释来抑制对这个特定语句的检查:

4) suppress inspection for this particular statement by adding commentary:

//noinspection ConstantConditions
return value.toString();

5) 至少添加，正如之前@ochi 建议使用 @SuppressWarnings("ConstantConditions") 注释，该注释可用于方法或整个类.

5) add at least, as earlier @ochi suggested use @SuppressWarnings("ConstantConditions") annotation which can be used for method or for whole class.

要调用此上下文菜单，请使用快捷键Alt+Enter(我认为它们对于所有操作系统都是通用的).

To invoke this context menu use shortcut keys Alt+Enter (I think they are common for all OS).

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