Re: hibernate question ?

I have an entity like
@Entity
public class Address {
@Id
private int id;
private String street;
private String city;
private String state;
private String zip;
private Set<Address> addressSet = new HashSet<Address>();

public int getId() {
return id;
}

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

public String getStreet() {
return street;
}

public void setStreet(String address) {
this.street = address;
}

public String getCity() {
return city;
}

public void setCity(String city) {
this.city = city;
}

public String getState() {
return state;
}

public void setState(String state) {
this.state = state;
}

public String getZip() {
return zip;
}

public void setZip(String zip) {
this.zip = zip;
}
public String toString() {
return "Address id: " + getId() +
", street: " + getStreet() +
", city: " + getCity() +
", state: " + getState() +
", zip: " + getZip();
}

@OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy =
"address")
public Set<Address> getAddressSet() {
return this.addressSet;
}

public void setAuthDevices(Set<Address> address) {
this.addressSet = address;
}

}

and entity :

@Entity
public class Student {
@Id
private int id;
private String name;

@ManyToOne(cascade=CascadeType.PERSIST)
Address address;

public int getId() {
return id;
}

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

public String getName() {
return name;
}

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

public Address getAddress() {
return address;
}

public void setAddress(Address address) {
this.address = address;
}

public String toString() {
return "Student id: " + getId() + " name: " + getName() +
" with " + getAddress();
}
}

if i do this :

Student emp = new Student();
emp.setId(1);
emp.setName("name");
Address addr = new Address();
addr.setId(1);
addr.setStreet("street");
addr.setCity("city");
addr.setState("state");
emp.setAddress(addr);
addr.getAddressSet().add(emp);
em.persist(emp);

the cascade attribute works and two insert are generated(cascade persist
works, but when
I do something like this :

Student emp = em.find(Student.class, 1L);
emp.setName("name");
Address addr = em.find(Adress.class, 1L);
addr.setStreet("streetOne");
emp.setAddress(addr);
em.persist(emp);

two sql updates are generates and address and student is updates, but
there is NO cascade = MERGE on Student entity... how is this POSSIBLE ?