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try..catch..finally statement
try {// ... try block ... } finally { // ... finally block ... }
try { // ... try block ... }
catch(error [:ErrorType1]) // ... catch block ... }
[catch(error[:ErrorTypeN]) { // ... catch block ... }]
[finally { // ... finally block ... }]
Enclose a block of code in which an error can occur, and then respond to the error. If any code
within the try code block throws an error (using the throw statement), control passes to the
catch block, if one exists, and then to the finally code block, if one exists. The finally
block always executes, regardless of whether an error was thrown. If code within the try block
doesn't throw an error (that is, if the try block completes normally), then the code in the
finally block is still executed. The finally block executes even if the try block exits using
a return statement.
A try block must be followed by a catch block, a finally block, or both. A single try block
can have multiple catch blocks but only one finally block. You can nest try blocks as
many levels deep as desired.
The error parameter specified in a catch handler must be a simple identifier such as e or
theException or x. The variable in a catch handler can also be typed. When used with
multiple catch blocks, typed errors let you catch multiple types of errors thrown from a single
try block.
If the exception thrown is an object, the type will match if the thrown object is a subclass of
the specified type. If an error of a specific type is thrown, the catch block that handles the
corresponding error is executed. If an exception that is not of the specified type is thrown, the
catch block does not execute and the exception is automatically thrown out of the try block
to a catch handler that matches it.
If an error is thrown within a function, and the function does not include a catch handler,
then the ActionScript interpreter exits that function, as well as any caller functions, until a
catch block is found. During this process, finally handlers are called at all levels.
Parameters
error:Object - The expression thrown from a throw statement, typically an instance of the
Error class or one of its subclasses.
202 ActionScript language elements