java 在接口上使用 .getclass()
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Using .getclass() on an interface
提问by Erik
This is probably a very easy question. Hey I'm a student and relatively new to java and I'm currently studying for a midterm that I have tomorrow. One of the practice questions I am stuck on is what happens when you have something like:
这可能是一个非常简单的问题。嘿，我是一名学生，对 Java 比较陌生，我目前正在学习明天的期中考试。我坚持的练习问题之一是当您遇到以下情况时会发生什么：
System.out.println(interface1.getClass().getName());
System.out.println(interface1.getClass().getName());
interface1has been declared as interface1 = class1. I'm pretty sure it would print "class1" and not "interface1" because interface1is not a class right? but I'm not sure as the question also says that if it produces a compile time error then say so. Our professor is known for tricking us and more then once I get back a quiz and still been confused as to why I got a problem wrong.
interface1已被声明为interface1 = class1. 我很确定它会打印“class1”而不是“interface1”，因为interface1它不是一个类，对吗？但我不确定，因为问题还说如果它产生编译时错误，那么就这么说。我们的教授以欺骗我们而闻名，而且当我回到测验时，我仍然对为什么我做错了问题感到困惑。
回答by G_H
It's not because it's an interface that you'd get class1, but because getClass()will resolve to the runtime class of the instance. Since you've created it as a class1, that's the runtime type. Won't give you a compile-time error.
这不是因为它是您将获得的接口class1，而是因为getClass()它将解析为实例的运行时类。由于您已将其创建为class1，这就是运行时类型。不会给你一个编译时错误。
Getting a Classobject for an interface is possible via reflection.
Class可以通过反射获取接口的对象。
Alternatively you can access the class more directly through the classkeyword:
或者，您可以通过class关键字更直接地访问该类：
String className = Runnable.class.getName();
