Question

I am using MySql database with JPA. my persistence.xml looks like

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0"
    xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
    <persistence-unit name="citheph">
        <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
        <class>persistence.citheph.pTerm</class>
        <class>persistence.citheph.pPublicationterm</class>
        <class>persistence.citheph.pPublicationauthor</class>
        <class>persistence.citheph.pPublication</class>
        <class>persistence.citheph.pCoauthorship</class>
        <class>persistence.citheph.pCitation</class>
        <class>persistence.citheph.pAuthor</class>
        <properties>
            <property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/cithepth" />
            <property name="javax.persistence.jdbc.password" value="amer1" />
            <property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver" />
            <property name="javax.persistence.jdbc.user" value="root" />
        </properties>

    </persistence-unit>
</persistence>

in my java code i do the following

EntityManagerFactory emf = Persistence.createEntityManagerFactory("citheph");
EntityManager em = emf.createEntityManager();

emf always come back null. the database is connected and pings successfully. I have even tried to change the persistence-unit name to something that doesn’t match the entry in the persistance.xml and I am still getting null. It is not throwing any exceptions. ofcourse when it gets to the second line in the code

EntityManager em = emf.createEntityManager();

I get a null pointer exception.

any help will be greatly appreciated.

Answer 1

Turn logging on finest and ensure no errors are occurring loading the persistence unit.

What environment are you using, do you have all the required jars on your classpath?