Java 检查布尔值是否为空
如何检查布尔值是否为空?因此，如果我知道hideInNav"为空.我该如何停止它从进一步执行?像下面这样的东西似乎不起作用，但为什么呢?
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 因为它是一个 原始数据类型(+一个 boolean 变量默认值值为 false).如果你想使用 null 值，你可以使用 Boolean 类.Boolean 是一种引用类型，这就是您可以将 null 分配给布尔变量"的原因.示例:
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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