Where the finally is necessary?

Question

I know how to use try-catch-finally. However I do not get the advance of using finally as I always can place the code after the try-catch block. Is there any clear example?

Answer 1

It's almost always used for cleanup, usually implicitly via a using statement:

FileStream stream = new FileStream(...);
try
{
    // Read some stuff
}
finally
{
    stream.Dispose();
}

Now this is not equivalent to

FileStream stream = new FileStream(...);
// Read some stuff
stream.Dispose();

because the "read some stuff" code could throw an exception or possibly return - and however it completes, we want to dispose of the stream.

So finally blocks are usually for resource cleanup of some kind. However, in C# they're usually implicit via a using statement:

using (FileStream stream = new FileStream(...))
{
    // Read some stuff
} // Dispose called automatically

finally blocks are much more common in Java than in C#, precisely because of the using statement. I very rarely write my own finally blocks in C#.