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package javax.persistence;

import java.lang.annotation.Target;
import java.lang.annotation.Retention;
import javax.persistence.CascadeType;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
import static javax.persistence.FetchType.LAZY;

/**
 * Defines a many-valued association with many-to-many multiplicity. 
 * If the Collection is defined using generics to specify the element 
 * type, the associated target entity class does not need to be 
 * specified; otherwise it must be specified.
 *
 * 

Every many-to-many association has two sides, the owning * side and the non-owning, or inverse, side. The join table is * specified on the owning side. If the association is bidirectional, * either side may be designated as the owning side. * *

The same annotation elements for the {@link OneToMany} * annotation apply to the ManyToMany annotation. * *

 *
 *    Example 1:
 *
 *    In Customer class:
 *
 *    @ManyToMany
 *    @JoinTable(name="CUST_PHONES")
 *    public Set getPhones() { return phones; }
 *
 *    In PhoneNumber class:
 *
 *    @ManyToMany(mappedBy="phones")
 *    public Set getCustomers() { return customers; }
 *
 *    Example 2:
 *
 *    In Customer class:
 *
 *    @ManyToMany(targetEntity=com.acme.PhoneNumber.class)
 *    public Set getPhones() { return phones; }
 *
 *    In PhoneNumber class:
 *
 *    @ManyToMany(targetEntity=com.acme.Customer.class, mappedBy="phones")
 *    public Set getCustomers() { return customers; }
 *
 *    Example 3:
 *
 *    In Customer class:
 *
 *    @ManyToMany
 *    @JoinTable(name="CUST_PHONE",
 *        joinColumns=
 *            @JoinColumn(name="CUST_ID", referencedColumnName="ID"),
 *        inverseJoinColumns=
 *            @JoinColumn(name="PHONE_ID", referencedColumnName="ID")
 *        )
 *    public Set getPhones() { return phones; }
 *
 *    In PhoneNumberClass:
 *
 *    @ManyToMany(mappedBy="phones")
 *    public Set getCustomers() { return customers; }
 * 
* * @since Java Persistence 1.0 */ @Target({METHOD, FIELD}) @Retention(RUNTIME) public @interface ManyToMany { /** * (Optional) The entity class that is the target * of the association. Optional only if the collection * property is defined using Java generics. * Must be specified otherwise. * *

Defaults to the parameterized type of * the collection when defined using generics. */ Class targetEntity() default void.class; /** * (Optional) The operations that must be cascaded to * the target of the association. *

Defaults to no operations being cascaded. */ CascadeType[] cascade() default {}; /** (Optional) Whether the association should be * lazily loaded or must be eagerly fetched. The * {@link FetchType#EAGER EAGER} strategy is a * requirement on the persistenceprovider runtime * that the associatedentities must be eagerly fetched. * The {@link FetchType#LAZY LAZY} strategy is a hint * to the persistence provider runtime. */ FetchType fetch() default LAZY; /** * The field that owns the relationship. Required unless * the relationship is unidirectional. */ String mappedBy() default ""; }





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