This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
If you have several versions of the same class (i.e. the package name and the class name match), the classloader picks up the first one listed in your classpath. For example, if your classpath looks like "C:\libs\foo.jar;C:\libs\bar.jar" and both foo.jar and bar.jar contain a class utils.text.StringHelper, the classloader loads the class from within foo.jar as it's listed first in the classpath. Did that help at all?