Class not found exception for com/google/appengine/tools/enhancer/Enhance when starting eclipse

Question

I did a fresh download of Eclipse Juno and installed Google App Engine SDK. After this whenever I start eclipse I get an error

Could not find the main class: com.google.appengine.tools.enhancer.Enhance. Program will Exit.

Edit: Looks like there is a Builder that gets added by the Google AppEngine Plugin. Eclipse tries to find this "Builder" and fails. I added the path to this builder which resides in plugins\com.google.appengine.eclipse.sdkbundle_1.8.3\appengine-java-sdk-1.8.3\lib to my system classpath.

Now I get a different error

DataNucleus Enhancer (version 3.1.1) : Enhancement of classes Aug 21, 2013 8:48:14 PM org.datanucleus.metadata.MetaDataManager loadClasses SEVERE: Class "in.chimanrao.model.Account" was not found in the CLASSPATH. Please check your specification and your CLASSPATH. org.datanucleus.exceptions.ClassNotResolvedException: Class "in.chimanrao.model.Account" was not found in the CLASSPATH. Please check your specification and your CLASSPATH.

How do I pass custom classpath to this DataNucleus Enhancer?

Answer 1

I solved it by installing JDK 1.7 and making it the default in Eclipse.

If you work with a database, install the previous version JDK 7u21 because the latest version has some issues with databases.