Hibernate does not define an entity when attempting to delete from a database

I can not figure out why the error Exception in thread "main" java.lang.IllegalArgumentException: Unknown entity: java.lang.Long when running the delete (Long id) method. Methods save(Item item), update(Item item) and findById(Long id work correctly. Tell save(Item item), update(Item item) and findById(Long id what could be the error. Class Item :

 import javax.persistence.*; import java.util.Date; @Entity @Table(name = "ITEM") public class Item { private Long id; private String name; private Date dateCreated; private Date lastUpdateDate; private String description; public Item() { } public Item(String name, Date dateCreated, Date lastUpdateDate, String description) { this.name = name; this.dateCreated = dateCreated; this.lastUpdateDate = lastUpdateDate; this.description = description; } @Id @SequenceGenerator(name = "IT_SQ", sequenceName = "ITEM_SEQ", allocationSize = 1) @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "IT_SQ") public Long getId() { return id; } @Column(name = "NAME") public String getName() { return name; } @Column(name = "DATE_CREATED") public Date getDateCreated() { return dateCreated; } @Column(name = "LAST_UPDATE_DATE") public Date getLastUpdateDate() { return lastUpdateDate; } @Column(name = "DESCRIPTION") public String getDescription() { return description; } public void setId(Long id) { this.id = id; } public void setName(String name) { this.name = name; } public void setDateCreated(Date dateCreated) { this.dateCreated = dateCreated; } public void setLastUpdateDate(Date lastUpdateDate) { this.lastUpdateDate = lastUpdateDate; } public void setDescription(String description) { this.description = description; } @Override public String toString() { return "Item{" + "id=" + id + ", name='" + name + '\'' + ", dateCreated=" + dateCreated + ", lastUpdateDate=" + lastUpdateDate + ", description='" + description + '\'' + '}'; } } 

Class ItemDAO :

 import org.hibernate.HibernateException; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.Transaction; import org.hibernate.cfg.Configuration; import org.hibernate.query.NativeQuery; public class ItemDAO { private static SessionFactory sessionFactory; private static final String SQL_GET_ITEM_BY_ID = "SELECT * FROM ITEM WHERE ID = ?"; public Item save(Item item){ Transaction transaction = null; try(Session session = createSessionFactory().openSession()) { transaction = session.getTransaction(); transaction.begin(); session.save(item); transaction.commit(); System.out.println("Saved successfully"); }catch (HibernateException e){ System.err.println("Saved is failed"); System.err.println(e.getMessage()); if (transaction != null) transaction.rollback(); } return item; } public void update(Item item){ Transaction transaction = null; try (Session session = createSessionFactory().openSession()){ transaction = session.getTransaction(); transaction.begin(); session.update(item); System.out.println("Update was successful"); transaction.commit(); }catch (HibernateException e){ System.err.println("Save is failed"); System.err.println(e.getMessage()); if (transaction != null) transaction.rollback(); } } public void delete(Long id){ Transaction transaction = null; try (Session session = createSessionFactory().openSession()){ transaction = session.getTransaction(); transaction.begin(); session.delete(id); System.out.println("Recording deleted successfully"); transaction.commit(); }catch (HibernateException e){ System.err.println("Save is failed"); System.err.println(e.getMessage()); if (transaction != null) transaction.rollback(); } } @SuppressWarnings("unchecked") public Item findById(Long id){ Item item; try (Session session = createSessionFactory().openSession()){ NativeQuery query = session.createNativeQuery(SQL_GET_ITEM_BY_ID); item = (Item) query.addEntity(Item.class).setParameter(1, id).getSingleResult(); }catch (HibernateException e){ System.err.println("Save is failed"); System.err.println(e.getMessage()); throw e; } System.out.println("Save is done"); return item; } private static SessionFactory createSessionFactory(){ if (sessionFactory == null){ sessionFactory = new Configuration().configure().buildSessionFactory(); } return sessionFactory; } } 

Pom file :

 <?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>crud-servlet</groupId> <artifactId>crud-servlet</artifactId> <version>1.0-SNAPSHOT</version> <packaging>war</packaging> <dependencies> <!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api --> <dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <version>4.0.0-b07</version> <!--<scope>provided</scope>--> </dependency> <dependency> <groupId>com.oracle</groupId> <artifactId>ojdbc7</artifactId> <version>12.1.0</version> </dependency> <!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-core --> <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate-core</artifactId> <version>5.2.16.Final</version> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.6.3</version> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <configuration> <source>1.8</source> <target>1.8</target> </configuration> </plugin> </plugins> </build> </project> 

File hibernate.cfg.xml :

 <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <property name="hibernate.connection.driver_class">oracle.jdbc.driver.OracleDriver</property> <property name="hibernate.connection.url">jdbc:oracle:thin:@gromcode-lesson.cjqbbseqr63c.eu-central-1.rds.amazonaws.com:1521:ORCL</property> <property name="hibernate.connection.username">main</property> <property name="hibernate.connection.password">ifgjrkzr</property> <property name="show_sql">true</property> <mapping class="Item"></mapping> </session-factory> <!--<open_tag params>value</open_tag>--> </hibernate-configuration> 

And actually the stack with an error:

  июн 26, 2018 7:35:33 PM org.hibernate.Version logVersion INFO: HHH000412: Hibernate Core {5.2.16.Final} июн 26, 2018 7:35:33 PM org.hibernate.cfg.Environment <clinit> INFO: HHH000206: hibernate.properties not found июн 26, 2018 7:35:33 PM org.hibernate.boot.jaxb.internal.stax.LocalXmlResourceResolver resolveEntity WARN: HHH90000012: Recognized obsolete hibernate namespace http://hibernate.sourceforge.net/hibernate-configuration. Use namespace http://www.hibernate.org/dtd/hibernate-configuration instead. Support for obsolete DTD/XSD namespaces may be removed at any time. июн 26, 2018 7:35:34 PM org.hibernate.annotations.common.reflection.java.JavaReflectionManager <clinit> INFO: HCANN000001: Hibernate Commons Annotations {5.0.1.Final} июн 26, 2018 7:35:34 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl configure WARN: HHH10001002: Using Hibernate built-in connection pool (not for production use!) июн 26, 2018 7:35:34 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator INFO: HHH10001005: using driver [oracle.jdbc.driver.OracleDriver] at URL [jdbc:oracle:thin:@gromcode-lesson.cjqbbseqr63c.eu-central-1.rds.amazonaws.com:1521:ORCL] июн 26, 2018 7:35:34 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator INFO: HHH10001001: Connection properties: {user=main, password=****} июн 26, 2018 7:35:34 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator INFO: HHH10001003: Autocommit mode: false июн 26, 2018 7:35:34 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl$PooledConnections <init> INFO: HHH000115: Hibernate connection pool size: 20 (min=1) июн 26, 2018 7:35:35 PM org.hibernate.dialect.Dialect <init> INFO: HHH000400: Using dialect: org.hibernate.dialect.Oracle10gDialect Exception in thread "main" java.lang.IllegalArgumentException: Unknown entity: java.lang.Long at org.hibernate.internal.SessionImpl.fireDelete(SessionImpl.java:1000) at org.hibernate.internal.SessionImpl.delete(SessionImpl.java:929) at ItemDAO.delete(ItemDAO.java:61) at Demo.main(Demo.java:23) Caused by: org.hibernate.MappingException: Unknown entity: java.lang.Long at org.hibernate.metamodel.internal.MetamodelImpl.entityPersister(MetamodelImpl.java:620) at org.hibernate.internal.SessionImpl.getEntityPersister(SessionImpl.java:1635) at org.hibernate.event.internal.DefaultDeleteEventListener.onDelete(DefaultDeleteEventListener.java:82) at org.hibernate.event.internal.DefaultDeleteEventListener.onDelete(DefaultDeleteEventListener.java:56) at org.hibernate.internal.SessionImpl.fireDelete(SessionImpl.java:993) ... 3 more Process finished with exit code -1 

It seems everything is correct, but something is missing somewhere ...