ACTIONSCRIPT 3 Developer’s Guide en

ACTIONSCRIPT 3.0 DEVELOPER’S GUIDE
Handling errors
try
{
try
{
trace(">");
throw new ApplicationError("some error which will be rethrown");
}
catch (error:ApplicationError)
{
trace("> " + error);
trace(">");
throw error;
}
catch (error:Error)
{
trace("> " + error);
}
}
catch (error:ApplicationError)
{
trace("> " + error);
}
The output from the previous snippet would be the following:
>
> ApplicationError: some error which will be rethrown
>
> ApplicationError: some error which will be rethrown
The nested try block throws a custom ApplicationError error that is caught by the subsequent catch block. This
nested catch block can try to handle the error, and if unsuccessful, throw the ApplicationError object to the enclosing
try..catch block.
Creating custom error classes
Flash Player 9 and later, Adobe AIR 1.0 and later
You can extend one of the standard Error classes to create your own specialized error classes in ActionScript. There
are a number of reasons to create your own error classes:
To identify specific errors or groups of errors that are unique to your application.
For example, take different actions for errors thrown by your own code, in addition to those errors trapped by a
Flash runtime. You can create a subclass of the Error class to track the new error data type in try..catch blocks.
To provide unique error display capabilities for errors generated by your application.
For example, you can create a new toString() method that formats your error messages in a certain way. You can
also define a lookupErrorString() method that takes an error code and retrieves the proper message based on
the user’s language preference.
A specialized error class must extend the core ActionScript Error class. Here is an example of a specialized AppError
class that extends the Error class:
Last updated 6/6/2012
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