i have 3 classes :
@Entity
@Table(name="companies")
public class Company implements Serializable {


private static final long serialVersionUID = -3322113303362981686L;

@Id
@Column(name="CMP_COMPANY_ID",nullable=false)
@GeneratedValue(strategy = GenerationType.AUTO)
private Integer id;

@Column(name="CMP_COMPANY_NAME",nullable=false)
private String name;

@OneToMany(mappedBy="company")
private Set<Item> items;


public Integer getId() {
return id;
}

public void setId(Integer id) {
this.id = id;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public Set<Item> getItems() {
return items;
}

public void setItems(Set<Item> items) {
this.items = items;
}
}

Items class :

Entity
@Table(name = "ELC_ITEMS")
public class Item implements Serializable{

private static final long serialVersionUID = 8635086262992868784L;

@EmbeddedId
public ItemPK itemPK;

@Column(name = "ITM_ITEM_NAME")
private String itemName;
}
And :
@Embeddable
public class ItemPK implements Serializable {


private static final long serialVersionUID = -5177491823551943094L;

@ManyToOne
@JoinColumn(name="ITM_COMP_ID", referencedColumnName="CMP_COMPANY_ID")
protected Company company;

public Company getCompany() {
return company;
}

public void setCompany(Company company) {
this.company = company;
}

@Column(name="ITM_ITEM_CODE", nullable=false)
private String itemCode;

public String getItemCode() {
return itemCode;
}

public void setItemCode(String itemCode) {
this.itemCode = itemCode;
}

public boolean equals(Object other) {
if (other instanceof ItemPK) {
final ItemPK otherItemPK = (ItemPK) other;
return (otherItemPK.company.equals(company) && otherItemPK.itemCode.equals(itemCode));
}
return false;
}

public int hashCode() {
return super.hashCode();
}


}

When i run the application i get this stuck trace:

Caused by: org.hibernate.AnnotationException: mappedBy reference an unknown target entity property: model.Item.company in model.Company.items
at org.hibernate.cfg.annotations.CollectionBinder.bindStarToManySecondPass(CollectionBinder.java:578)
at org.hibernate.cfg.annotations.CollectionBinder$1.secondPass(CollectionBinder.java:543)
at org.hibernate.cfg.CollectionSecondPass.doSecondPass(CollectionSecondPass.java:43)
at org.hibernate.cfg.Configuration.secondPassCompile(Configuration.java:1130)
at org.hibernate.cfg.AnnotationConfiguration.secondPassCompile(AnnotationConfiguration.java:329)
at org.hibernate.cfg.Configuration.buildMappings(Configuration.java:1115)
at org.hibernate.ejb.Ejb3Configuration.buildMappings(Ejb3Configuration.java:1226)
at org.hibernate.ejb.EventListenerConfigurator.configure(EventListenerConfigurator.java:173)
at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:854)
at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:425)
at org.hibernate.ejb.HibernatePersistence.createContainerEntityManagerFactory(HibernatePersistence.java:131)
at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:224)
at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:291)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1369)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1335)

What is wrong with my mapping ?

Do you have a mapping for the items class in your hibernate configuration mapping file? Problably, it's the addition of the Item.class to the config object when Hibernate is initialized. Maybe it's spelled incorrectly?

You're mappedBy suggests company is in the Item class but in actuality its in the ItemPk class. So, try this instead:

It works !!!
Thank You Very much

I have another question refers to this code.
Now my ItemPK is the @Embeddable class of Item.class and i try to connect to ItemCrossReference.Class

@Entity
public class ItemCrossReference {

@EmbeddedId
public ItemCrossReferencePK itemCrossReferencePK;

@ManyToOne
@JoinColumns( {
@JoinColumn(name = "REF_MANUF_CMP_CODE", referencedColumnName = "ITM_COMP_ID"),
@JoinColumn(name = "REF_MANUF_REF_CODE", referencedColumnName = "ITM_ITEM_CODE") })
protected Item manufItem;
}

@Entity
public class Item implements Serializable{
private static final long serialVersionUID = 8635086262992868784L;

@EmbeddedId
public ItemPK itemPK;

//Setter and getter ...
}

@Embeddable
public class ItemPK implements Serializable {

private static final long serialVersionUID = -5177491823551943094L;

@ManyToOne
@JoinColumn(name="ITM_COMP_ID", referencedColumnName="CMP_COMPANY_ID")
protected Company company;

public Company getCompany() {
return company;
}

@OneToMany(mappedBy="itemCrossReference.itemPK")
private Set<ItemCrossReference> itemCrossReferences;

public void setCompany(Company company) {
this.company = company;
}

@Column(name="ITM_ITEM_CODE", nullable=false)
private String itemCode;

public String getItemCode() {
return itemCode;
}

public void setItemCode(String itemCode) {
this.itemCode = itemCode;
}

public void setItemCrossReferences(Set<ItemCrossReference> itemCrossReferences) {
this.itemCrossReferences = itemCrossReferences;
}

public Set<ItemCrossReference> getItemCrossReferences() {
return itemCrossReferences;
}

public boolean equals(Object other) {
if (other instanceof ItemPK) {
final ItemPK otherItemPK = (ItemPK) other;
return (otherItemPK.company.equals(company) && otherItemPK.itemCode.equals(itemCode));
}
return false;
}

public int hashCode() {
return super.hashCode();
}
}

The error now is:
mappedBy reference an unknown target entity property: model.ItemCrossReference.itemCrossReference.itemPK in model.Item.itemCrossReferences

This is very confusing, what is wrong with this one ?

Nice one. But how about when using @IdClass instead of @EmbeddedId?

I solve the problem 'mappedBy reference an unknown target entity property:' with this way.

public class C implements Serializable {

@OneToMany(mappedBy = "usedby2") // this mappedBy is the same name of field in the class Cc
private List<Object> usedby2;
}

public class Cc implements Serializable {
@JoinColumn(name = "USEDBY2", referencedColumnName = "ID", nullable = false, insertable = false, updatable = false)
@ManyToOne(optional = false)
private Object usedby2; // this field name is the same mappedBy in the class Cc
}

public class CircuitcircuitPK implements Serializable {
@Basic(optional = false)
@Column(name = "USEDBY2", nullable = false)
private BigInteger usedby2;

}

I hope help you, too late i know.

I solved that problem.
Please check getter setter method names.It should be of your mapped by name
e.g If you are mapped by department then your getter & setter method name must be getDepartment() and setDepartment()