java：boolean instanceOf Boolean？ [英] java: boolean instanceOf Boolean?

问题描述

我有点困惑：我有一个函数，一个对象作为参数。但是编译器不会抱怨，如果我只是传递一个原始，甚至认可一个布尔基元作为布尔对象。为什么会这样呢？

I'm a bit confused: I have a function, that takes an Object as argument. But the compiler does not complain if I just pass a primitive and even recognizes a boolean primitive as Boolean Object. Why is that so?

public String test(Object value)
{
   if (! (value instanceof Boolean) ) return "invalid";
   if (((Boolean) value).booleanValue() == true ) return "yes";
   if (((Boolean) value).booleanValue() == false ) return "no";
   return "dunno";
}

String result = test(true);  // will result in "yes"

推荐答案

true '将 Autoboxed 到 Boolean ，它是一个 Object 。

Because primitive 'true' will be Autoboxed to Boolean and which is a Object.

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