What is the purpose of "finally" in try/catch/finally

Question

The syntax will change from language to language, but this is a general question.

What is the difference between this....

try {      Console.WriteLine("Executing the try statement.");      throw new NullReferenceException(); } catch (NullReferenceException e) {      Console.WriteLine("{0} Caught exception #1.", e); }        finally {      Console.WriteLine("Executing finally block."); } 

and this....

try {     Console.WriteLine("Executing the try statement.");     throw new NullReferenceException(); } catch (NullReferenceException e) {     Console.WriteLine("{0} Caught exception #1.", e); }         Console.WriteLine("Executing finally block."); 

I keep seeing it being used, so I assume there's a good reason to use finally, but I can't figure out how it's any different from just putting code after the statement since it will still run.

Is there ever a scenario where finally doesn't run?

Answer 1

In your example, it doesn't make a whole lot of difference.

Picture this, though:

    try     {         Console.WriteLine("Executing the try statement.");         throw new NullReferenceException();     }     catch (SomeOtherException e)     {         Console.WriteLine("{0} Caught exception #1.", e);     }            finally     {         Console.WriteLine("Executing finally block.");     }      Console.WriteLine("Executing stuff after try/catch/finally."); 

In this case, the catch won't catch the error, so anything after the whole try/catch/finally will never be reached. However, the finally block will still run.

Answer 2

try {     throw new Exception("Error!"); } catch (Exception ex) {     throw new Exception(ex, "Rethrowing!"); } finally {     // Will still run even through the catch kicked us out of the procedure }  Console.WriteLine("Doesn't execute anymore because catch threw exception");