Java检查布尔值是否为空 [英] Java check if boolean is null

问题描述

如何检查布尔值是否为null?因此，如果我知道"hideInNav"为空.我怎么停 它从进一步执行?像下面这样的东西似乎不起作用，但是为什么呢?

How do you check if a boolean is null or not? So if I know "hideInNav" is null. How do I stop it from further executing? Something like the below doesn't seem to work but why?

boolean hideInNav = parent.getProperties().get("hideInNav", false);
String hideNavigation = hideInNav != null ? hideInNav : "";

推荐答案

boolean只能是true或false，因为它是

boolean can only be true or false because it's a primitive datatype (+ a boolean variables default value is false). You can use the class Boolean instead if you want to use null values. Boolean is a reference type, that's the reason you can assign null to a Boolean "variable". Example:

Boolean testvar = null;
if (testvar == null) { ...}

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