Java中的Object，Reference ID和Reference Variable之间有什么区别? [英] What is the difference between an Object , Reference ID , and Reference Variable in Java?

问题描述

java中的以下内容之间有什么区别?

What is difference between the following in java :

1. 对象

1. Object

参考ID

参考变量

当我看到这样的语句时:

When I see statements like this:

Emp e = new Emp();

这里Emp是类，但是e不是它的对象?如果是这样..在其他地方我已经看到了:

Here Emp is class, but e is not its object? If that is so .. somewhere else I have seen this:

如果是这样的话，那么..somewhere就像

cos if it is so then ..somewhere is see like

Emp e = new Local(); 

其中local是Emp的子类.那么e在这种情况下是什么意思?它有什么作用?

Where local is a child class of Emp. So what does e mean in this case? What does it hold?

推荐答案

对象本质上是堆中生活的一块内存. (对象的部分内存结构包括对该对象类的引用.)

An object is, essentially, a chunk of memory living in the heap. (Part of the memory structure of objects includes a reference to the class of that object.)

对象变量(如本例中的e)包含对驻留在堆中的对象的引用.

Object variables in Java (like e, in this example) contain references to objects living in the heap.

类与所有这些类完全不同；它们可能描述了这种类型的对象的结构，并具有方法实现等，但是类与其他对象生活在完全不同的内存区域中.

Classes are completely different from all of these; they might describe the structure of objects of that type, and have method implementations and the like, but classes live in an entirely different area of memory from other objects.

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