You may use a little bit generic exceptions for that conditions. For e.g. ArgumentException is meant to be used when anything goes wrong with the parameters to a method (with the exception of ArgumentNullException). Generally you would not need exceptions like LessThanZeroException, NotPrimeNumberException etc. Think of the user of your method. The number of the conditions that she will want to handle specifically is equal to the number of the type of the exceptions that your method needs to throw. This way, you can determine how detailed exceptions you will have.

顺便说一下，总是尝试为库的用户提供一些避免异常的方法。TryParse就是一个很好的例子，它的存在使你不必使用int。解析并捕获异常。在您的情况下，您可能希望提供一些方法来检查用户名是否有效或密码是否正确，这样您的用户(或您)就不必进行大量异常处理。这将有望产生更易于阅读的代码和更好的性能。

for me Exception should be thrown when a required technical or business rule fails. for instance if a car entity is associated with array of 4 tires ... if one tire or more are null ... an exception should be Fired "NotEnoughTiresException" , cuz it can be caught at different level of the system and have a significant meaning through logging. besides if we just try to flow control the null and prevent the instanciation of the car . we might never never find the source of the problem , cuz the tire isn't supposed to be null in the first place .

If it's code running inside a loop that will likely cause an exception over and over again, then throwing exceptions is not a good thing, because they are pretty slow for large N. But there is nothing wrong with throwing custom exceptions if the performance is not an issue. Just make sure that you have a base exception that they all inherite, called BaseException or something like that. BaseException inherits System.Exception, but all of your exceptions inherit BaseException. You can even have a tree of Exception types to group similar types, but this may or may not be overkill.

因此，简短的回答是，如果它不会导致显著的性能损失(除非抛出大量异常，否则不应该如此)，那么就继续执行。

You may use a little bit generic exceptions for that conditions. For e.g. ArgumentException is meant to be used when anything goes wrong with the parameters to a method (with the exception of ArgumentNullException). Generally you would not need exceptions like LessThanZeroException, NotPrimeNumberException etc. Think of the user of your method. The number of the conditions that she will want to handle specifically is equal to the number of the type of the exceptions that your method needs to throw. This way, you can determine how detailed exceptions you will have.

顺便说一下，总是尝试为库的用户提供一些避免异常的方法。TryParse就是一个很好的例子，它的存在使你不必使用int。解析并捕获异常。在您的情况下，您可能希望提供一些方法来检查用户名是否有效或密码是否正确，这样您的用户(或您)就不必进行大量异常处理。这将有望产生更易于阅读的代码和更好的性能。

最终，决定取决于是使用异常处理更有助于处理此类应用程序级错误，还是通过您自己的机制(如返回状态代码)更有帮助。我不认为哪个更好有一个严格的规则，但我会考虑:

Who's calling your code? Is this a public API of some sort or an internal library? What language are you using? If it's Java, for example, then throwing a (checked) exception puts an explicit burden on your caller to handle this error condition in some way, as opposed to a return status which could be ignored. That could be good or bad. How are other error conditions in the same application handled? Callers won't want to deal with a module that handles errors in an idiosyncratic way unlike anything else in the system. How many things can go wrong with the routine in question, and how would they be handled differently? Consider the difference between a series of catch blocks that handle different errors and a switch on an error code. Do you have structured information about the error you need to return? Throwing an exception gives you a better place to put this information than just returning a status.

我个人的指导方针是:当发现当前代码块的基本假设为假时抛出异常。

例1:假设我有一个函数，它应该检查任意类，如果该类继承自List<>，则返回true。这个函数问一个问题:“这个对象是List的后代吗?”这个函数永远不会抛出异常，因为它的操作中没有灰色地带——每个单独的类要么继承了List<>，要么继承了List<>，所以答案总是“是”或“否”。

Example 2: say I have another function which examines a List<> and returns true if its length is more than 50, and false if the length is less. This function asks the question, "Does this list have more than 50 items?" But this question makes an assumption - it assumes that the object it is given is a list. If I hand it a NULL, then that assumption is false. In that case, if the function returns either true or false, then it is breaking its own rules. The function cannot return anything and claim that it answered the question correctly. So it doesn't return - it throws an exception.

这与“负载问题”逻辑谬误相当。每个函数都问一个问题。如果给出的输入使该问题成为谬误，则抛出异常。对于返回void的函数，这条线很难画出来，但底线是:如果函数对其输入的假设违反了，它应该抛出异常，而不是正常返回。

这个等式的另一方面是:如果你发现你的函数经常抛出异常，那么你可能需要改进它们的假设。