Keyword

Finally


Description

Contains code that will run after a method or function is finished, even if a RuntimeException has occurred.

Usage

Try

// Your code Catch

[Finally]

//code that executes even if runtime exceptions were raised End [ Try ]

Notes

Sometimes a method needs to do some cleanup work whether it is finishing normally or aborting early because of an exception. The optional Finally block at the end of a method or function runs after its exception handlers, if it has any. Code in this block will be executed even if an exception has occured, whether the exception was handled or not.

More commonly you will use Finally as part of a Try statement.

For example, you can write:

Sub SomeFunction()
  // some code here...
Finally
  // some more code that will always execute (unless a Return statement is used, see below)
End Sub

However, the code in the Finally block does not execute if you exit the method with a Return statement. See the following code:

Sub SomeFunction(x As Integer)
  If x = 0 Then
    Return // -> the Finally block won't execute
  End If
Finally
  Break // Debugger would stop here to check if it executes
End Sub

See also the entries for the Sub and Function statements.


Returning from a finally block

You should not use Return statements within a Finally block. The execution of a Return statement will cause any exceptions raised inside the Try and Catch blocks to be lost to the caller.

Here is an example:

Sub Test()
  Raise New OutOfBoundsException
Finally
  Return // This is a bad idea!
End Sub

If you call this Test method, it will return as if there had been no exception raised inside. Therefore, avoid Return statements at all costs. If you really want to drop any raised exceptions, it is suggested that you be more explicit of that intention by adding a Catch block.

Also note that because a Return statement will skip any following Finally blocks, code that requires cleanup should be nested in its own Try block, with any return statement outside that block. Finally blocks at the method level are better avoided.

Sample code

This simple example shows a Finally block that executes even after an exception.

Try
  Raise New RuntimeException
Finally
  // Executes even though the exception is not handled
  MessageBox("Finally")
End Try

Compatibility

All project types on all supported operating systems.

See also

Catch, Function, Sub statements; Exception, Try statements.