Visual Basic® 2010 Unleashed

The Throw Keyword

There are situations in which you need to programmatically throw exceptions or in which you catch exceptions but you do not want to handle them in the Catch block that intercepted exceptions. Programmatically throwing exceptions can be accomplished via the Throw keyword. For example, the following line of code throws an ArgumentNullException that typically occurs when a method receives a null argument:

Throw New ArgumentNullException

Typically you need to manually throw exceptions when they should be handled by another portion of code, also in another application. A typical example is when you develop class libraries. A class library must be the most abstract possible, so you cannot decide what actions to take when an exception ...