Catching and Re-throwing Exceptions

When catching exceptions, you may want to log some exception information but afterwards pass on the same exception to the caller. Logging information about the exception requires a catch block. Catching the exception nullifies the effect of the exception and lets the program continue executing normally after the catch block executes.

To reactivate the exception for the caller:

• Inside the catch block (either for a general exception or for a specific exception) type throw followed by a semicolon ( Figure 11.25 ).

  Figure 11.25 While throw ; by itself looks awkward , it's a quick way of re-throwing the same exception. Alternatively, you could just write throw ex; in the code here.

   public void OrderChecks(int Amount) {   try   {      MakeWithdrawal(5.00);   }   catch (AccountOverdrawnException ex)   {      LogProblemAccount(ex.AccountNumber);  throw;  } } 

Tip

• Alternatively you can allow the original exception to dissipate and generate a new exception. If you still want to provide information about the original exception you could chain the exceptions as illustrated in "Building an Exception Chain."