blocks|key|1750226|text|我对两者的用法的理解是这样的:使用==表示概念上的相等(在上下文中，这两个参数的含义是否相同？)，使用.Equals表示具体的相等(这两个参数实际上是完全相同的对象吗？)。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1750227|编辑:+Kevin+Sheffield的链接文章更好地解释了价值与引用相等…|1750228|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

My understanding of the uses of both was this: use == for conceptual equality (in context, do these two arguments mean the same thing?), and .Equals for concrete equality (are these two arguments in actual fact the exact same object?).

Edit: Kevin Sheffield's linked article does a better job of explaining value vs. reference equality…

blocks|key|1750252|text|您可能希望使用.Equals，因为以后可能会有人出现并为您的类重载它们。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1750253|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

You may want to use .Equals as someone may come along at a later time and overload them for you class.

blocks|key|1535361|text|string+x+=+"hello";
string+y+=+String.Copy(x);
string+z+=+"hello";|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1535362|测试x是否指向与y相同的对象|unstyled|offset|length|style|CODE|1535363|(object)x+==+(object)y++//+false
x.ReferenceEquals(y)++++//+false
x.ReferenceEquals(z)++++//+true+(because+x+and+z+are+both+constants+they
++++++++++++++++++++++++//+++++++will+point+to+the+same+location+in+memory)|1535364|测试x是否具有与y相同的字符串值|1535365|x+==+y++++++++//+true
x+==+z++++++++//+true
x.Equals(y)+++//+true
y+==+"hello"++//+true|1535366|请注意，这与Java不同。在Java语言中，==操作符不是重载的，所以在Java语言中一个常见的错误是：|1535367|y+==+"hello"++//+false+(y+is+not+the+same+object+as+"hello")|1535368|对于Java语言中的字符串比较，您需要始终使用.equals()|1535369|y.equals("hello")++//+true|1535370|entityMap^0|0|2|1|8|1|0|0|2|1|8|1|0|0|M|2|0|0|N|9|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|11|8|@$G|12|H|13|I|J]|$G|14|H|15|I|J]]|9|@]|A|$]]|$1|K|3|L|5|6|7|16|8|@]|9|@]|A|$B|C]]|$1|M|3|N|5|F|7|17|8|@$G|18|H|19|I|J]|$G|1A|H|1B|I|J]]|9|@]|A|$]]|$1|O|3|P|5|6|7|1C|8|@]|9|@]|A|$B|C]]|$1|Q|3|R|5|F|7|1D|8|@$G|1E|H|1F|I|J]]|9|@]|A|$]]|$1|S|3|T|5|6|7|1G|8|@]|9|@]|A|$B|C]]|$1|U|3|V|5|F|7|1H|8|@$G|1I|H|1J|I|J]]|9|@]|A|$]]|$1|W|3|X|5|6|7|1K|8|@]|9|@]|A|$B|C]]|$1|Y|3|-4|5|F|7|1L|8|@]|9|@]|A|$]]]|Z|$]]

<pre><code>string x = "hello";
string y = String.Copy(x);
string z = "hello";
</code></pre>

To test if <code>x</code> points to the same object as <code>y</code>:

<pre><code>(object)x == (object)y // false
x.ReferenceEquals(y) // false
x.ReferenceEquals(z) // true (because x and z are both constants they
 // will point to the same location in memory)
</code></pre>

To test if <code>x</code> has the same string value as <code>y</code>:

<pre><code>x == y // true
x == z // true
x.Equals(y) // true
y == "hello" // true
</code></pre>

Note that this is different to Java.
In Java the <code>==</code> operator is not overloaded so a common mistake in Java is:

<pre><code>y == "hello" // false (y is not the same object as "hello")
</code></pre>

For string comparison in Java you need to always use <code>.equals()</code>

<pre><code>y.equals("hello") // true
</code></pre>

blocks|key|1750316|text|我打算把这篇文章作为对公认答案的评论，但我认为在决定采取哪条路线时，这一点值得考虑。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1750317|dotnetfiddle：https://dotnetfiddle.net/gESLzO|offset|length|1750318|小提琴代码：|1750319|++++Object+a+=+null;
++++Object+b+=+new+Object();

++++//+Ex+1
++++Console.WriteLine(a+==+b);
++++//+Ex+2
++++Console.WriteLine(b+==+a);

++++//+Ex+3+++++
++++Console.WriteLine(b.Equals(a));
++++//+Ex+4
++++Console.WriteLine(a.Equals(b));|code-block|syntax|javascript|1750320|前3个WriteLine示例可以工作，但第四个会抛出一个异常。1和2使用==，这是一个静态方法，不需要实例化任何一个对象。|style|CODE|1750321|示例3之所以有效，是因为b是实例化的。|1750322|示例4失败，因为a为null，因此不能在空对象上调用方法。|1750323|因为我尽可能懒惰地编写代码，所以我使用==，特别是在处理其中一个对象(或两个)都可以为空的情况下。如果我没有这样做，那么在调用.Equals()之前，我必须首先做一个空检查。|1750324|entityMap|0|LINK|mutability|MUTABLE|url|https://dotnetfiddle.net/gESLzO^0|0|D|V|0|0|0|0|10|2|0|C|1|0|8|1|A|4|0|J|2|1R|9|0^^$0|@$1|2|3|4|5|6|7|14|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|15|8|@]|9|@$D|16|E|17|1|18]]|A|$]]|$1|F|3|G|5|6|7|19|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|1A|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|1B|8|@$D|1C|E|1D|O|P]]|9|@]|A|$]]|$1|Q|3|R|5|6|7|1E|8|@$D|1F|E|1G|O|P]]|9|@]|A|$]]|$1|S|3|T|5|6|7|1H|8|@$D|1I|E|1J|O|P]|$D|1K|E|1L|O|P]]|9|@]|A|$]]|$1|U|3|V|5|6|7|1M|8|@$D|1N|E|1O|O|P]|$D|1P|E|1Q|O|P]]|9|@]|A|$]]|$1|W|3|-4|5|6|7|1R|8|@]|9|@]|A|$]]]|X|$Y|$5|Z|10|11|A|$12|13]]]]

I was going to post this as a comment on the accepted answer, but I think this deserves to be considered when determining which route to take.

dotnetfiddle: <a href="https://dotnetfiddle.net/gESLzO" rel="noreferrer">https://dotnetfiddle.net/gESLzO</a>

Fiddle code:

<pre><code> Object a = null;
 Object b = new Object();

 // Ex 1
 Console.WriteLine(a == b);
 // Ex 2
 Console.WriteLine(b == a);

 // Ex 3 
 Console.WriteLine(b.Equals(a));
 // Ex 4
 Console.WriteLine(a.Equals(b));
</code></pre>

The first 3 WriteLine examples will work, but the fourth throws an exception. 1 and 2 use <code>==</code>, which is a static method that does not require either object to be instantiated.

Example 3 works because <code>b</code> is instantiated.

Example 4 fails because <code>a</code> is <code>null</code>, and thus a method can not be called on a null object.

Because I try to code as lazily as possible, I use <code>==</code>, especially when working with scenarios where either object (or both) can be null. If I didn't, I'd have to do a null check, first, before being able to call <code>.Equals()</code>.

So, when I was a comparative novice to the novice I am right now, I used to think that these two things were syntactic sugar for each other, i.e. that using one over the other was simply a personal preference. Over time, I'm come to find that these two are not the same thing, even in a default implementation (see <a href="http://web.archive.org/web/20081205081158/http://blogs.msdn.com:80/jmstall/archive/2005/03/06/386064.aspx" rel="nofollow noreferrer">this</a> and <a href="http://web.archive.org/web/20090710210823/http://blogs.msdn.com:80/jmstall/archive/2005/03/12/394645.aspx" rel="nofollow noreferrer">this</a>). To further confuse the matter, each can be overridden/overloaded separately to have completely different meanings. 

Is this a good thing, what are the differences, and when/why should you use one over the other?

== vs. Object.Equals(object) in .NET

Java

因此，当我还是一个相对新手的时候，我曾经认为这两个东西是语法上的糖，也就是说，使用一个而不是另一个仅仅是个人偏好。随着时间的推移，我发现这两者并不是一回事，甚至在缺省实现中也是如此(请参阅和)。更令人困惑的是，每一个都可以被分别覆盖/重载，以具有完全不同的含义。这是一件好事吗，有什么区别，什么时候/为什么你应该使用一种...

问.NET中的==与Object.Equals(object)
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