Java 等于一个类

我们是否可以对 Class变量而不是 equals进行 ==并期望得到相同的结果？

例如:

Class clazz = xyz;

案例 A:

if(clazz == Date.class) {
// do something
}

案例 B:

if(Date.class.equals(clazz)) {
// do something
}

案例 A 和案例 B 在功能上是否相同？

java

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小开

最佳答案

Class is final, so its equals() cannot be overridden. Its equals() method is inherited from Object which reads

public boolean equals(Object obj) {
return (this == obj);
}

So yes, they are the same thing for a Class, or any type which doesn't override equals(Object)

To answer your second question, each ClassLoader can only load a class once and will always give you the same Class for a given fully qualified name.

小开

Yes.

Take a look at the Class class description and note that it inherits equals from Object, for which the method reads:

"The equals method for class Object implements the most discriminating possible equivalence relation on objects; that is, for any non-null reference values x and y, this method returns true if and only if x and y refer to the same object (x == y has the value true)."

小开

Yes, since the code for equals(...) for class is the following:

public boolean equals(Object obj) {
return (this == obj);
}