在catch块中捕获异常后，是否可以再次在try块中执行代码？

Question

I want to execute the code in the try block again after an exception is caught. Is that possible somehow?

For Eg:

try
{
    //execute some code
}
catch(Exception e)
{
}

If the exception is caught I want to go in the try block again to "execute some code" and try again to execute it.

Answer 1

Put it in a loop. Possibly a while loop around a boolean flag to control when you finally want to exit.

bool tryAgain = true;
while(tryAgain){
  try{
    // execute some code;
    // Maybe set tryAgain = false;
  }catch(Exception e){
    // Or maybe set tryAgain = false; here, depending upon the exception, or saved details from within the try.
  }
}

Just be careful to avoid an infinite loop.

A better approach may be to put your "some code" within its own method, then you could call the method from both within the try and the catch as appropriate.

Answer 2

If you wrap your block in a method, you can recursively call it

void MyMethod(type arg1, type arg2, int retryNumber = 0)
{
    try
    {
        ...
    }
    catch(Exception e)
    {
        if (retryNumber < maxRetryNumber)
            MyMethod(arg1, arg2, retryNumber+1)
        else
            throw;
    }
}

or you could do it in a loop.

int retries = 0;

while(true)
{
    try
    {
        ...
        break; // exit the loop if code completes
    }
    catch(Exception e)
    {
        if (retries < maxRetries)
            retries++;
        else
            throw;
    }
}

Answer 3

int tryTimes = 0;
while (tryTimes < 2) // set retry times you want
{
    try
    {
        // do something with your retry code
        break; // if working properly, break here.
    }
    catch
    {
        // do nothing and just retry
    }
    finally
    {
        tryTimes++; // ensure whether exception or not, retry time++ here
    }
}

Answer 4

already answered in these (and other) links

Better way to write retry logic without goto

Cleanest way to write retry logic?

How can I improve this exception retry scenario?

Answer 5

What's wrong with the ole goto ?

 Start:
            try
            {
                //try this
            }
            catch (Exception)
            {

                Thread.Sleep(1000);
                goto Start;
            }

Answer 6

There is another way to do it (though as others have mentioned, not really recommended). Here's an example using a file download retry to more closely match the retry keyword found in Ruby in VB6.

RetryLabel:

try
{
    downloadMgr.DownLoadFile("file:///server/file", "c:\\file");
    Console.WriteLine("File successfully downloaded");
}
catch (NetworkException ex)
{
    if (ex.OkToRetry)
        goto RetryLabel;
}

Answer 7

This should work:

count = 0;
while (!done) {
  try{
    //execute some code;
    done = true;
  }
  catch(Exception e){
  // code
  count++;
  if (count > 1) { done = true; }
  }
}