Cycle was detected in the build path of project

Question

Hi
I was trying to create a Test application for MDB.
Here from the webContent I call the service locator in the EJB folder and get the bean object. Using the object I need to put a message in the MQ.
The onMessage method<present under EJB folder> picks up the message<which is a key> and then it has to refer the value in the Map which is under the ../WebContent/Javasource/..
But when I try to complile the project it is giving a error stating that A cycle was detected in the build path of project: MDBTestEJB.
How do I solve this ?? Please help ?

Answer 1

The fix for this - regardless of IDE - is to use a
bit of common sense, and good old-fashioned logic
(remember that?). You've obviously got (at least) 2
things that are dependent on each other, which - if
you remember the Chicken and Egg problem* - can't
possibly work. Work it out for yourself, you're
writing software, after all. If A needs B to do some
work but can't because B needs A first, you've got
problems
* sensible "it was the egg. Something
not-quite-like-a-chicken-but-close mated with
something-else-not-quite-like-a-chicken, and produced
an egg that eventually hatched into a chicken"
notwithstandingOK georgemc, I allowed you to motivate me to look for a better fix. I think I came up with a solution but I'd like to see if you, or anyone else, agrees with it.
First let me say that I'm using a persistence layer, which I've never done before, and with cardinality annotations different classes need to reference each other cyclically.
My problem was that I had class A in project 1 that depended on class B in project 2, but class B (project 2) also depended on class A (project 1). This meant that I had project 2 on the project 1 build path and vice versa; which is why I was getting the error.
After your post I started to think about it and it seems that my original solution didn't do a very good job of utilizing the extensibility that Java's OO gives us. My new solution is to remove any reference of class A that is in class B and also remove project 1 from the project 2 build path. Then extend class B into class ChildOf_B in project 1 and insert the references to class A in the new child class. I of course keep project 2 on the project 1 build path.
I've since told eclipse to throw an error for build path cycles instead of a warning and I no longer have any problems.