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Throws a user-defined exception.
Syntax
throw expression
Parameters
| Parameter | Description |
|---|---|
| expression | The value to throw. |
Description
Use the throw statement to throw an exception. When you throw an exception, an expression specifies the value of the exception. The following code throws several exceptions.
Examples
Example 1. Throw an object
You can specify an object when you throw an exception. You can then reference the object's properties in the catch block. The following example creates an object myUserException of type UserException and uses it in a throw statement.
Example 2. Throw an object
The following example tests an input string for a U.S. zip code. If the zip code uses an invalid format, the throw statement throws an exception by creating an object of type ZipCodeFormatException.
Example 3. Rethrow an exception
You can use throw to rethrow an exception after you catch it. The following example catches an exception with a numeric value and rethrows it if the value is over 50. The rethrown exception propagates up to the enclosing function or to the top level so that the user sees it.