Re: hibernate question ?

Tom Anderson <>
Sat, 28 Aug 2010 11:18:13 +0100
On Fri, 27 Aug 2010, Lew wrote:

On 08/27/2010 04:47 AM, mike wrote:

I have an entity like
public class Address {
    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) { = id;


    @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 :

public class Student {
    private int id;
    private String name;

    Address address;

    public int getId() {
        return id;

    public void setId(int id) { = id;


if i [sic] do this :

Student emp = new Student();
    Address addr = new Address();

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

    Student emp = em.find(Student.class, 1L);
    Address addr = em.find(Adress.class, 1L);

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

There's no need to shout so loudly.

I suspect but do not know that it has to do with mixing field and method
annotations in the same class. Don't do that anyway.

It might be coincidence that the cascade specified in the class where you did
that is the one that didn't work.

You probably don't need to initialize 'Address#addressSet' explicitly. I'm
puzzled why people do that in entity classes. What does it provide?

The ability to say new Address().getAddressSet().add(something) without
getting a NullPointerException. Didn't we talk about this before?

I'm more concerned about the setter for the ID field myself.

Well, and the fact that the OP has put the address set in the address
rather than in the student, that the setter for it is called
setAuthDevices, that he calls his Student variable 'emp', and various
other small signs that he has no idea what he's doing.


Why did one straw break the camel's back? Here's the secret: the million
other straws underneath it - it's all mathematics. -- Mos Def

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