我同意japollock的说法当你不确定手术的结果时就放弃接受。调用api、访问文件系统、数据库调用等。任何时候你都要超越编程语言的“界限”。

我想补充一点，请随意抛出一个标准异常。除非你打算做一些“不同”的事情(忽略，电子邮件，日志，显示twitter鲸鱼图片之类的东西)，否则不要费心自定义异常。

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 .

避免抛出异常的主要原因是抛出异常涉及大量开销。

下面这篇文章指出的一件事是，例外是针对异常条件和错误的。

错误的用户名不一定是程序错误，而是用户错误……

下面是关于。net中的异常的一个不错的起点: http://msdn.microsoft.com/en-us/library/ms229030 (VS.80) . aspx

其他人建议不应该使用异常，因为在正常流程中，如果用户输入错误，就会出现错误的登录。我不同意，我不明白其中的道理。与打开文件相比。如果该文件不存在或由于某种原因不可用，则框架将抛出异常。使用上述逻辑是微软的一个错误。他们应该返回一个错误代码。解析、webrequest等也一样。

I don't consider a bad login part of a normal flow, it's exceptional. Normally the user types the correct password, and the file does exist. The exceptional cases are exceptional and it's perfectly fine to use exceptions for those. Complicating your code by propagating return values through n levels up the stack is a waste of energy and will result in messy code. Do the simplest thing that could possibly work. Don't prematurely optimize by using error codes, exceptional stuff by definition rarely happens, and exceptions don't cost anything unless you throw them.

我同意japollock的说法当你不确定手术的结果时就放弃接受。调用api、访问文件系统、数据库调用等。任何时候你都要超越编程语言的“界限”。

我想补充一点，请随意抛出一个标准异常。除非你打算做一些“不同”的事情(忽略，电子邮件，日志，显示twitter鲸鱼图片之类的东西)，否则不要费心自定义异常。

异常与返回错误代码参数应该是关于流控制的，而不是哲学(错误有多“异常”):

void f1() throws ExceptionType1, ExceptionType2 {}

void catchFunction() {
  try{
    while(someCondition){
      try{
        f1(); 
      }catch(ExceptionType2 e2){
        //do something, don't break the loop
      }
    }
  }catch(ExceptionType1 e1){
    //break the loop, do something else
  }

}