Annotations and exception handling

[Nathan Russell]

I wonder if anyone can help.
I'm trying to write a struts 2 component and as part of that I am trying to use XWork's DI (I've decided to post here as I think its more to do with Java annotations rather than struts or xworks)
I want to use the struts2 / xworks Inject annotation to get a value from the struts properties files into my class. Esssentially this is what I want to do:

public class Form extends org.apache.struts2.components.Form {

	@Inject("fred")
	private String name;

...

Where 'fred' in the example is the name of a property in the properties file. Obviously 'fred' is a value I've used to test what happens when the name/value pair is not found in the properties file. In this case the xworks class throws an exception.
This is fine, except I cant work out how to catch the exception! I am not familiar with java5 annotations (I cut my teeth on the 1.4 stream ) - so if anyone could point me in the right direction I'd very much appreciate it.

Thanks

Nathan

[Ernest Friedman-Hill]

The annotation doesn't do anything itself. I'm not familiar with the tool you're using, but someplace, there is code that will look for these annotations and try to instantiate your class. It's that code that will throw the exception. In these kinds of systems, that code tends to be buried pretty far down in the guts, and I'm not sure there's any easy way to catch an exception like this and continue. A missing property would be considered a fatal configuration error.

If this is the annotation you're talking about, looks like there's a "required" argument which defaults to "true" -- I imagine toggling that lets you prevent the exception altogether.

[Nathan Russell]

Ernest - yes, that was the annotation I was after, and by setting the required arguement to false it does not throw the exception, which means I can handle it as I need to
Thank you very much for your help with this, very much appreciated;

Cheers

Nathan

[David Newton]

(Moving to Struts. XWork is being folded into Struts, and the version of Guice it uses is a very early fork, so... it's pretty much Struts.)