lazily initialize collections in their getters

[mars1412]

I am thinking of using lazy initialization of collections in thier getters:
example:

private java.util.Set<MyEntity> myEntities;

 public java.util.Set<MyEntity> getMyEntities() {
 if (myEntities == null) {
 myEntities = new HashSet<MyEntity>();
 }
 return myEntities;

 }

this would be nice because I would not need the explicit null checks in my buissneslogic.

however I have a bad feeling about this - I'm if this will work in all cases with lazy loading, hibernate proxies and stuff I might not even know about.

What do you think?

[jaikiran]

I might be missing something here, but isn't the following approach simpler?

private java.util.Set<MyEntity> myEntities = new HashSet<MyEntity>();

 public java.util.Set<MyEntity> getMyEntities() {
 return myEntities;

 }

[mars1412]

basically it's the same, but with your approach the getter could return null, if anyone called

setMyEntities(null)

[jaikiran]

"mars1412" wrote:
basically it's the same, but with your approach the getter could return null, if anyone called

setMyEntities(null)

Well, that's what the user would expect right? If someone explicitly sets it to null, then he should get back null, isn't it?

[jaikiran]

Coming back to your original question:

"mars1412" wrote:



however I have a bad feeling about this - I'm if this will work in all cases with lazy loading, hibernate proxies and stuff I might not even know about.

What do you think?

I don't see any problems in this approach, in terms of lazy loading and proxies in Hibernate.

[mars1412]

thanks for the answers

"jaikiran" wrote:
Well, that's what the user would expect right? If someone explicitly sets it to null, then he should get back null, isn't it?

Yes, you are right. In the case of collection initalisation the other approach is more appropriate.

When I think about it, the lazy initalization approach in the getters came from handling embedded components.
As defined by hibernate, the embedded component will be null, if all its elements are null.
so hibernate would set the embedded component to null, if all its fields in the database are null.
that would break code like this:

myEntity().getEmbedded().setEmbeddedField(someValue)

In this case this initalization would not help:

private EmbeddedComponentTyp embedded = new EmbeddedComponentTyp();

[skajotde]

It rather question for hibernate forum... forum.hibernate.org

With getter are problems. Hibernate check getters if object changed. And when you get object from database and no explicity write, hibernate invoke flush and compare hydrated objects before transaction and after. Getters return other values and hibernate executes additional updates (even you only executes selects - true in standard way but i guess it is configurable with cache mode or something), this may ends with very poor performance with huge amount of updates.