noclassdeffounderror, PhoneNumberUtil & Google App Engine

PhoneNumberUtil is not a supported class in GAE. Simply adding the jar into the jre/lib/ext will let you through the compilation, but you probably will get a java.lang.noclassdeffounderror after deployment.

The problem cannot be solved through Eclipse interface. What I do is to, first, copy the jar (mine one is libphonenumber-6.2.jar) to war\WEB-INF\lib, and then add the jar to build path in the project explorer.

This solution also works for other external jars.

To download PhoneNumberUtil, go to https://code.google.com/p/libphonenumber/.  

Mission accomplished!