异常处理

Question

I need to know witch of this two handling of exceptions is better and why?? Or some other way to do better.

try{
                if (String.IsNullOrEmpty(filePath))
                {
                    throw new ArgumentNullException("The path is null or empty.", "filePath");
                }

or

 try{
                if (String.IsNullOrEmpty(filePath))
                {
                    Console.WriteLine("The path is null or empty");
                } 

Answer 1

I would recommend the second approach, except that you don't need the try/catch in this case. Exceptions are for handling exceptional cases. If you can prevent those cases with an if condition you should prefer this. If you are some performance optimization maniac you probably already know that throwing and catching exceptions could be more expensive compared to testing for conditions.

Answer 2

If not having the path breaks your whole application flow, throwing an exception is a good idea so that you can recover the state of the application for another try, or show a dialog to the user.

On the other hand, Console.WriteLine("The path is null or empty"); just notifies the user of the situation and moves on. If your execution flow is not harmed with, this will add minimal overhead to your application, thus preferable.

Answer 3

Use code contracts instead. Especially for things like preconditions (ie, your example).

Answer 4

If the situation is an error to be expected, use return code or similar. Like a file not existing or such

If it is an unexpected situation (null as an argument ) use an excpetion.

Exception handling is expensive, so use wisely.

hth

Mario

Answer 5

Well, first of all in the second code you don't throw any exception, you simply write a message to the console. This means that the second one won't signal anything in a windows forms or wpf application or - worse - a web application. Besides that, by throwing an exception you are able to intercept it on another stage of the application, and behaving correspondingly, whereas Console.WriteLine is only specific to the scope where you invoked it.

You might also want to consider whether throwing an exception is appropriate at all. This occurs in all cases where your code could gently handle the "exceptional" case, like by providing default values or such.

Answer 6

I can't say this for sure because the rest of your program isn't there; but I'm guessing the first option is going to kill your program, while the second is going to just print something to the console and then continue with the rest of your program. So the answer to this question depends more on what YOU want it to do? Want the program to die when this situation happens? Throw the exception and don't handle it. Want to reprompt the user when this happens? Then use your second option, but turn your IF statement into a while loop, and just prompt until the condition is no longer true.