title: JPA - createEntityManagerFactory returns Null
body: <p>Noob question here. I'm following <a href="http://schuchert.wikispaces.com/JPA+Tutorial+1+-+Getting+Started#Create%20Your%20First%20Entity" rel="nofollow noreferrer">this example/tutorial</a> to try and isolate a problem I keep getting on my main project. Problem is, the entityManagerFactory keeps returning null (thus, I get a NullPointerExcept when trying to run the first JUnit test.)</p>
  
  <p>I'm currently on Eclipse Indigo (JavaEE) - JRE7 - Hibernate 3.6.7 and JBoss 7</p>
  
  <p>And here's my persistence.xml (again, a copipasta taken right from the tutorial)</p>
  
  <pre><code>&lt;persistence&gt;
          &lt;persistence-unit name="examplePersistenceUnit" 
                            transaction-type="RESOURCE_LOCAL"&gt;
              &lt;properties&gt;
                  &lt;property name="hibernate.show_sql" value="false" /&gt;
                  &lt;property name="hibernate.format_sql" value="false" /&gt;
  
                  &lt;property name="hibernate.connection.driver_class" 
                            value="org.hsqldb.jdbcDriver" /&gt;
                  &lt;property name="hibernate.connection.url" 
                            value="jdbc:hsqldb:mem:mem:aname" /&gt;
                  &lt;property name="hibernate.connection.username" value="sa" /&gt;
  
                  &lt;property name="hibernate.dialect" 
                            value="org.hibernate.dialect.HSQLDialect" /&gt;
                  &lt;property name="hibernate.hbm2ddl.auto" value="create" /&gt;
              &lt;/properties&gt;
          &lt;/persistence-unit&gt;
      &lt;/persistence&gt;
  </code></pre>
  
  <p>Things I've already tried/found out so far:</p>
  
  <ul>
  <li><p>Seems this problem <a href="https://stackoverflow.com/questions/7189066/jpa-entitymanager-is-not-initialized-null">tends to occur</a> if you try to create a factory
  with a persistence unit that is not listed in the persistence.xml</p></li>
  <li><p>Double-checked that the necessary JARs are included in Eclipse's
  Build Path Libraries, which Google suggested may be a possible cause
  for a createEntityManagerFactory() call to short-circuit and return
  null (instead of just throwing an exception or logging a message)</p></li>
  <li><p>Might be due to a possible error <a href="https://stackoverflow.com/questions/4003069/jpa-and-derby-null-pointer-exception">whilst configuring</a> Hibernate
  connection?</p></li>
  </ul>
  
  <p>I've been hitting this wall for the past couple of weeks, so it goes without saying that any help/general direction tips are MUCH appreciated :D</p>