让Foo.class它有什么作用？ [英] Foo.class what does it do?

问题描述

我寻找一些Java代码，有这个代码，我经常看到。

I m looking at some Java code, and there is this code that I see often.

Foo.class

这是用来指示类的类型？是类似于

This is being used to to indicate the Type of the class? is that similar to

Foo.GetType();
typeof(Foo);

在C＃？

这是什么被用来做什么？什么的S的含义？

What is it being used for ? and what s the meaning of it?

推荐答案

是让Foo.class 在Java中等同于 typeof运算（富）在C＃。见JLS 的 15.8.2节有关的更多信息类文本的

Yes, Foo.class in Java is equivalent to typeof(Foo) in C#. See section 15.8.2 of the JLS for more information on class literals.

这是的不的与调用的GetType（）上的参考，从而得到的执行时间的类的一个对象。在Java相当于是 someReference.getClass（）。

It's not the same as calling GetType() on a reference, which gets the execution time type of an object. The Java equivalent of that is someReference.getClass().

一个原因你可能更经常看到它在Java中代码比C＃是相对于仿制药。这并不完全是稀奇事是这样的：

One reason you may see it more often in Java code than in C# is in relation to generics. It's not entirely unusual to have something like:

public class Generic<T>
{
    private final Class<T> clazz;

    public Generic(Class<T> clazz)
    {
        this.clazz = clazz;
    }
}

这允许类进行反思执行时间访问等等，这是只在Java必要的，因为的类型擦除的，由此泛型类型的对象通常不能决定在执行时其类型的参数。

This allows execution-time access to the class for reflection etc. This is only necessary in Java due to type erasure, whereby an object of a generic type can't normally determine its type arguments at execution time.

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