The persistence doesn't recognize the entity class

Question

I am developing a java program about some lotteries of my country, it has a database with the lottos and other numbers. There is no problem with the entity classes, but when I run the problem my persistence unit does not recognize one entity class. I am a beginner in java, thanks in advance.

Here is the Numbers entity class:

@Entity
@Table(name = "NUMBERS")
@XmlRootElement
@NamedQueries({
    @NamedQuery(name = "Numbers.findAll", query = "SELECT n FROM Numbers n")
    , @NamedQuery(name = "Numbers.findById", query = "SELECT n FROM Numbers n WHERE n.id = :id")
    , @NamedQuery(name = "Numbers.findByNum", query = "SELECT n FROM Numbers n WHERE n.num = :num AND n.lotto = :lotto")
    , @NamedQuery(name = "Numbers.findByAssociated", query = "SELECT n FROM Numbers n WHERE n.num = :num AND n.associated = :associated AND n.lotto = :lotto")
    , @NamedQuery(name = "Numbers.findByLotto", query = "SELECT n FROM Numbers n WHERE n.lotto = :lotto")})
public class Numbers implements Serializable {

    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    @Column(name = "ID")
    private Integer id;
    @Basic(optional = false)
    @Column(name = "NUM")
    private int num;
    @Basic(optional = false)
    @Column(name = "ASSOCIATED")
    private int associated;
    @Basic(optional = false)
    @Column(name = "LOTTO")
    private String lotto;

And the code that I use to insert Numbers in the database:

public static boolean insertAlert(EntityManager em, Numbers an) {
        boolean success = false;

        Alert alert = Check.createAlert(Check.CONFIRMATION, "Añadir números asociados", "¿Deseas añadir estos números?");
        Optional<ButtonType> result = alert.showAndWait();

        if (result.get() == ButtonType.OK) {
            em.getTransaction().begin();
            em.persist(an);

            if (em.isJoinedToTransaction()) {
                em.getTransaction().commit();
                System.out.println("NUMBERS SUCCESSFULLY ADDED!");
                alert = Check.createAlert(Check.INFORMATION, "OK", "Números añadidos!");
                alert.showAndWait();
                success = true;
            }
            
            em.clear();
        }

        return success;
}

The persistence.xml:

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.1" xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">
  <persistence-unit name="LotterPU" transaction-type="RESOURCE_LOCAL">
    <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
    <class>lotter.lottoClasses.Gordo</class>
    <class>lotter.lottoClasses.Primitiva</class>
    <class>lotter.lottoClasses.Eurojackpot</class>
    <class>lotter.lottoClasses.Seis49</class>
    <class>lotter.lottoClasses.Superonce</class>
    <class>lotter.lottoClasses.Bonoloto</class>
    <class>lotter.lottoClasses.Siete39</class>
    <class>lotter.lottoClasses.Euromillones</class>
    <class>lotter.Repetition</class>
    <class>lotter.Numbers</class>
    <properties>
      <property name="javax.persistence.jdbc.url" value="jdbc:derby:DB;create=true"/>
      <property name="javax.persistence.jdbc.user" value=""/>
      <property name="javax.persistence.jdbc.driver" value="org.apache.derby.jdbc.EmbeddedDriver"/>
      <property name="javax.persistence.jdbc.password" value=""/>
      <property name="javax.persistence.schema-generation.database.action" value="create"/>
    </properties>
  </persistence-unit>
</persistence>

The persistence unit recognizes all my entity classes but not this one, I don't know how to resolve this...

Caused by: java.lang.IllegalArgumentException: Object: lotter.Numbers[ id=null ] is not a known entity type.
    at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.registerNewObjectForPersist(UnitOfWorkImpl.java:4228)
    at org.eclipse.persistence.internal.jpa.EntityManagerImpl.persist(EntityManagerImpl.java:496)
    at lotter.Numbers.insertAlert(Numbers.java:165)
    at lotter.Numbers.insertAssociated(Numbers.java:150)
    at lotter.Lotter.start(Lotter.java:41)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$8(LauncherImpl.java:863)
    at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$7(PlatformImpl.java:326)
    at com.sun.javafx.application.PlatformImpl.lambda$null$5(PlatformImpl.java:295)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$6(PlatformImpl.java:294)
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
Exception running application lotter.Lotter

JPA Logging:

[EL Finer]: metadata: 2019-10-17 16:14:45.632--ServerSession(1410760993)--Thread(Thread[JavaFX Application Thread,5,main])--Searching for default mapping file in file:/Users/~/NetBeansProjects/Lotter/build/classes/ (There is no English translation for this message.)
[EL Finer]: metadata: 2019-10-17 16:14:45.643--ServerSession(1410760993)--Thread(Thread[JavaFX Application Thread,5,main])--Searching for default mapping file in file:/Users/~/NetBeansProjects/Lotter/build/classes/ (There is no English translation for this message.)
[EL Config]: metadata: 2019-10-17 16:14:45.803--ServerSession(1410760993)--Thread(Thread[JavaFX Application Thread,5,main])--The access type for the persistent class [class lotter.lottoClasses.Bonoloto] is set to [FIELD].
[EL Config]: metadata: 2019-10-17 16:14:45.825--ServerSession(1410760993)--Thread(Thread[JavaFX Application Thread,5,main])--The access type for the persistent class [class lotter.lottoClasses.Euromillones] is set to [FIELD].
[EL Config]: metadata: 2019-10-17 16:14:45.827--ServerSession(1410760993)--Thread(Thread[JavaFX Application Thread,5,main])--The access type for the persistent class [class lotter.Repetition] is set to [FIELD].
[EL Config]: metadata: 2019-10-17 16:14:45.832--ServerSession(1410760993)--Thread(Thread[JavaFX Application Thread,5,main])--The access type for the persistent class [class lotter.lottoClasses.Gordo] is set to [FIELD].
[EL Config]: metadata: 2019-10-17 16:14:45.833--ServerSession(1410760993)--Thread(Thread[JavaFX Application Thread,5,main])--The access type for the persistent class [class lotter.lottoClasses.Seis49] is set to [FIELD].
[EL Config]: metadata: 2019-10-17 16:14:45.834--ServerSession(1410760993)--Thread(Thread[JavaFX Application Thread,5,main])--The access type for the persistent class [class lotter.lottoClasses.Primitiva] is set to [FIELD].
[EL Config]: metadata: 2019-10-17 16:14:45.835--ServerSession(1410760993)--Thread(Thread[JavaFX Application Thread,5,main])--The access type for the persistent class [class lotter.lottoClasses.Siete39] is set to [FIELD].
[EL Config]: metadata: 2019-10-17 16:14:45.835--ServerSession(1410760993)--Thread(Thread[JavaFX Application Thread,5,main])--The access type for the persistent class [class lotter.lottoClasses.Superonce] is set to [FIELD].
[EL Config]: metadata: 2019-10-17 16:14:45.836--ServerSession(1410760993)--Thread(Thread[JavaFX Application Thread,5,main])--The access type for the persistent class [class lotter.lottoClasses.Eurojackpot] is set to [FIELD].
[EL Config]: metadata: 2019-10-17 16:14:45.837--ServerSession(1410760993)--Thread(Thread[JavaFX Application Thread,5,main])--The alias name for the entity class [class lotter.lottoClasses.Bonoloto] is being defaulted to: Bonoloto.
[EL Config]: metadata: 2019-10-17 16:14:45.868--ServerSession(1410760993)--Thread(Thread[JavaFX Application Thread,5,main])--The alias name for the entity class [class lotter.lottoClasses.Euromillones] is being defaulted to: Euromillones.
[EL Config]: metadata: 2019-10-17 16:14:45.869--ServerSession(1410760993)--Thread(Thread[JavaFX Application Thread,5,main])--The alias name for the entity class [class lotter.Repetition] is being defaulted to: Repetition.
[EL Config]: metadata: 2019-10-17 16:14:45.87--ServerSession(1410760993)--Thread(Thread[JavaFX Application Thread,5,main])--The alias name for the entity class [class lotter.lottoClasses.Gordo] is being defaulted to: Gordo.
[EL Config]: metadata: 2019-10-17 16:14:45.871--ServerSession(1410760993)--Thread(Thread[JavaFX Application Thread,5,main])--The alias name for the entity class [class lotter.lottoClasses.Seis49] is being defaulted to: Seis49.
[EL Config]: metadata: 2019-10-17 16:14:45.873--ServerSession(1410760993)--Thread(Thread[JavaFX Application Thread,5,main])--The alias name for the entity class [class lotter.lottoClasses.Primitiva] is being defaulted to: Primitiva.
[EL Config]: metadata: 2019-10-17 16:14:45.874--ServerSession(1410760993)--Thread(Thread[JavaFX Application Thread,5,main])--The alias name for the entity class [class lotter.lottoClasses.Siete39] is being defaulted to: Siete39.
[EL Config]: metadata: 2019-10-17 16:14:45.875--ServerSession(1410760993)--Thread(Thread[JavaFX Application Thread,5,main])--The alias name for the entity class [class lotter.lottoClasses.Superonce] is being defaulted to: Superonce.
[EL Config]: metadata: 2019-10-17 16:14:45.878--ServerSession(1410760993)--Thread(Thread[JavaFX Application Thread,5,main])--The alias name for the entity class [class lotter.lottoClasses.Eurojackpot] is being defaulted to: Eurojackpot.
[EL Finest]: jpa: 2019-10-17 16:14:46.059--ServerSession(1410760993)--Thread(Thread[JavaFX Application Thread,5,main])--End predeploying Persistence Unit LotterPU; session file:/Users/user/NetBeansProjects/Lotter/build/classes/_LotterPU; state Predeployed; factoryCount 0
[EL Finer]: weaver: 2019-10-17 16:14:46.059--Thread(Thread[JavaFX Application Thread,5,main])--JavaSECMPInitializer - transformer is null.
[EL Finest]: jpa: 2019-10-17 16:14:46.059--ServerSession(1410760993)--Thread(Thread[JavaFX Application Thread,5,main])--Begin predeploying Persistence Unit LotterPU; session file:/Users/user/NetBeansProjects/Lotter/build/classes/_LotterPU; state Predeployed; factoryCount 0
[EL Finest]: jpa: 2019-10-17 16:14:46.059--ServerSession(1410760993)--Thread(Thread[JavaFX Application Thread,5,main])--End predeploying Persistence Unit LotterPU; session file:/Users/user/NetBeansProjects/Lotter/build/classes/_LotterPU; state Predeployed; factoryCount 1
[EL Finest]: jpa: 2019-10-17 16:14:46.065--ServerSession(1410760993)--Thread(Thread[JavaFX Application Thread,5,main])--Begin deploying Persistence Unit LotterPU; session file:/Users/user/NetBeansProjects/Lotter/build/classes/_LotterPU; state Predeployed; factoryCount 1
[EL Finer]: 2019-10-17 16:14:46.088--ServerSession(1410760993)--Thread(Thread[JavaFX Application Thread,5,main])--Could not initialize Validation Factory. Encountered following exception: java.lang.NoClassDefFoundError: javax/validation/Validation
[EL Finest]: properties: 2019-10-17 16:14:46.092--ServerSession(1410760993)--Thread(Thread[JavaFX Application Thread,5,main])--property=eclipselink.logging.logger; value=org.eclipse.persistence.logging.DefaultSessionLog

Answer 1

Persist only takes on entity not a list of.

So you have to iterate over the array and persist each Numbers object separately.

 for (Numbers n : ans) {
     em.persist(ans);
 }

Answer 2

Common reasons for this error:

1. An older persistence.xml file is on the class path that doesn't have your lotter.Numbers entry.
2. The class loader used to obtain the EntityManager isn't the same one that loaded the 'an' Answer instance you are passing to the em.persist call.

The first issue is far more common, and can be found more easily by enabling EclipseLink logging and then checking the log when it deploys the persistence unit to see what classes and mappings are loaded. Variations of it are just deploying the wrong jar, having an older jar on the class path first etc.

EclipseLink uses the class to lookup the metadata in a hash map, so if different class loaders are used, it won't find anything for it. This is a less common issue that depends on how you are loading your EntityManagerFactory and the container classloader structure. You would have problems with more then just one of your JPA entities, but it would depend on where they are coming from too.

Answer 3

I had the same problem and none of the answers here fixed it.

My solution was to updated my EclipseLink version from 2.5.1 to the latest version 2.7.7 as described in this other post.