它有助于控制名称空间污染。

对于类中的复杂逻辑，我发现私有静态方法在创建隔离逻辑时很有用，其中实例输入在方法签名中明确定义，并且不会发生实例副作用。所有输出必须通过返回值或out/ref参数。将复杂的逻辑分解成无副作用的代码块可以提高代码的可读性和开发团队对它的信心。

另一方面，它可能导致类被大量实用方法所污染。通常，逻辑命名、文档和团队编码约定的一致应用程序可以缓解这种情况。

读起来很有趣: http://thecuttingledge.com/?p=57

ReSharper实际上并不是建议您将方法设置为静态的。 你应该问问自己，为什么这个方法在那个类中，而不是在它的签名中出现的类之一…

但ReSharper documentaion是这么说的: http://confluence.jetbrains.net/display/ReSharper/Member+can+be+made+static

我希望您已经理解了静态方法和实例方法之间的区别。而且，答案可以有长有短。其他人已经给出了很长的答案。

我的简短回答是:是的，你可以像ReSharper建议的那样将它们转换为静态方法。这样做没有坏处。相反，通过将方法设置为静态，实际上是在保护该方法，这样就不会不必要地将任何实例成员插入该方法。通过这种方式，您可以实现OOP原则“最小化类和成员的可访问性”。

When ReSharper is suggesting that an instance method can be converted to a static one, it is actually telling you, "Why the .. this method is sitting in this class but it is not actually using any of its states?" So, it gives you food for thought. Then, it is you who can realize the need for moving that method to a static utility class or not. According to the SOLID principles, a class should have only one core responsibility. So, you can do a better cleanup of your classes in that way. Sometimes, you do need some helper methods even in your instance class. If that is the case, you may keep them within a #region helper.

它有助于控制名称空间污染。

在我看来，性能、名称空间污染等都是次要的。问问自己什么是合乎逻辑的。该方法在逻辑上操作类型的实例，还是与类型本身相关?如果是后者，则将其设置为静态方法。只有当它与不受您控制的类型相关时，才将其移动到实用程序类中。

Sometimes there are methods which logically act on an instance but don't happen to use any of the instance's state yet. For instance, if you were building a file system and you'd got the concept of a directory, but you hadn't implemented it yet, you could write a property returning the kind of the file system object, and it would always be just "file" - but it's logically related to the instance, and so should be an instance method. This is also important if you want to make the method virtual - your particular implementation may need no state, but derived classes might. (For instance, asking a collection whether or not it's read-only - you may not have implemented a read-only form of that collection yet, but it's clearly a property of the collection itself, not the type.)