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Could not initialize class com.sample.PMF (Google app engine)

Answer 1

A:

The stack trace did not help much, but one reason for not initializing the PersistenceManagerFactory is that it could not find a persistence unit that you specified in the JDOHelper.getPersistenceManagerFactory(String) method.

e.g. If your PMF's get() method looks like this:

public static synchronized PersistenceManagerFactory get() {
    if(pmfInstance == null)  {
        pmfInstance = JDOHelper.getPersistenceManagerFactory(
              "transactions-optional");
    }
    return pmfInstance;
}

Then you must have a jdoconfig.xml in your classpath (e.g. WEB-INF/classes) that defines a persistence unit as follows: (with same name that you used in getPersistenceManagerFactory). In this case "transactions-optional"

    <persistence-manager-factory name="transactions-optional">
        <property name="javax.jdo.PersistenceManagerFactoryClass" value="org.datanucleus.store.appengine.jdo.DatastoreJDOPersistenceManagerFactory"/>
        <property name="javax.jdo.option.ConnectionURL" value="appengine"/>
        <property name="javax.jdo.option.NontransactionalRead" value="true"/>
        <property name="javax.jdo.option.NontransactionalWrite" value="false"/>
    </persistence-manager-factory>

naikus 2010-07-29 16:07:24

I have exactly same code out here.

Webbisshh 2010-07-30 06:56:56

Is jdoconfig.xml in your classpath?

naikus 2010-07-30 07:14:06

I have tried the greeting example from google, and it worked! but my my project is giving this error... one quick question : my saveStudent(name) method is static : does that make any difference?

Webbisshh 2010-07-30 13:40:52

Answer 2

A:

Solved : I was calling the above code from a static method, now i made it an instance method and it worked. but still confused?

Webbisshh 2010-08-05 20:43:25

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Could not initialize class com.sample.PMF (Google app engine)

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