For the last few days I’ve been messing with ColdFusion exception handling, specifically on the TRY/CATCH block side. At first I was greatly intrigued by the fact that you could throw exceptions based off Java classes derived from the RuntimeExceptionclass. That would look something like this.

<cfset illegalArgument = CreateObject("java", "java.lang.IllegalArgumentException").init("Bad argument dude!")>

<cftry>
	<!--- Do some code here. Throw a fake exception for demonstration purposes --->
	<cfif 1 NEQ 2><cfthrow object="#illegalArgument#"></cfif>

<cfcatch type="Any">
	<cfdump var="#CFCATCH#">
</cfcatch>
</cftry>

This code instantiates an object of type IllegalArgumentException and throws an error upon a test condition failure (albeit a false one). This may not seem like much on the surface but what this means is that you can create your own custom exception classes to handle conditions where an error should occur, and you’d like execution flow to cease and be rerouted.

Let’s say that you wanted to throw an error if a phone number posted to the page wasn’t formatted like 999-999-9999. Let us also say that you wanted to create a custom error class in Java to be thrown on this condition. Here is what the java class, and the code to use it would look like.

import java.lang.RuntimeException;
import java.lang.String;

public class myPhoneNumberFormatException extends RuntimeException {
	public myPhoneNumberFormatException() { super(); }
	public myPhoneNumberFormatException(String message) { super(message); }
}

To use it…

<cfset phoneNumberFormatException = CreateObject("java", "myPhoneNumberFormatException").init("Invalid phone number format!")>

<cftry>
	<cfif NOT phoneNumber.trim().matches('[0-9]{3}-[0-9]{3}-[0-9]{4}'>
		<cfthrow object="#phoneNumberFormatException#">
	</cfif>

<cfcatch type="Any">
	<cfdump var="#CFCATCH#">
</cfcatch>
</cftry>

After going through all this, though, I began to question if there was any added benefit into diving into the Java side versus just using a technique of defining exception error codes and messages in a structure, for example. Then, after trying this, I also realized that ColdFusion provides the execution stack to you after an exception has been thrown. Perfect!

So at this point I was pretty happy… But then I discovered that THROW and RETHROW DO NOT EXIST IN CFSCRIPT!!! Oh… my… gawd… BAH!!

Aside from that last little disappointment I am quite happy with the mechanisms that ColdFusion provides for TRY/CATCH exception handling.