Loading two classes in different JARs

Question

I got two classes with the same package in different JARs. Until the previous version, both classes were identical, so i had no issues in loading them. Now, one of them has a new method added and if I want to access it, not only should I import the class with that package, i also need to make sure the jar with the correct class comes first in the classpath.

i.e. javac -classpath "%classpath%;a.jar;b.jar" MyClasses..

where a.jar has the class with my new method.

Now, how do i ensure this when my app goes to production, where it's deployed as an EAR file, with all the libraries under WEB-INF/lib?

How do I know which jar gets the preference over the other? Is it the alphabetical order like a.jar is given the first preference over b.jar?

I've read this safe-class-imports-from-jar-files thread and got to know about writing a custom classloader, but is there a better simpler solution that? Cos I'm just going to access this method in that whole JAR in this current project and writing a classloader seems a bit overkill.

And please don't ask me "Why the hell same class with same package in different JARs?" It's absolutely out of my control and it'll take some time to get this corrected.

Environment details: IBM WAS 6.1 on their 1.5 Java.

Please ask me more questions, if I don't make much sense. Thanks in advance!

Answer 1

You can try to change the startup script of your server and specify the jar with the correct class in the bootclasspath by using java -Xbootclasspath .... Otherwise there is no guarantee which one of the 2 jars will load up first.