[eclipselink-users] UPDATE: IndirectSet cannot be cast to java.util.Tree

[Martin Dames <m.dames@xxxxxx>]

Ok, I tried a bit and didn't get a solution:

I changed the fetch type to EAGER instead of LAZY.

Now I get another ClassCastException :

java.lang.ClassCastException: java.util.HashSet cannot be cast to java.util.TreeSet

The setter method from the last post (see below) will convert the passed Set into a TreeSet, so there should just be an instance of TreeSet in my children set, but EclipseLink is creating a HashSet !?!.

I tried to use OrderBy Annotation:

@OrderBy(value="firstname")

@OneToMany (mappedBy = "entity", fetch=FetchType.EAGER, cascade = {CascadeType.ALL})
private Set<Child> childrens = new TreeSet<Child>();

in hope that it will return an instance of TreeSet (which is sorted at first place in ascending order), but this does not work either.

Thank you for your support!

Martin.

Anfang der weitergeleiteten E-Mail:

Von: Martin Dames <m.dames@xxxxxx>

Datum: 2. Dezember 2009 20:08:55 MEZ

An: eclipselink-users@xxxxxxxxxxx

Betreff: IndirectSet cannot be cast to java.util.TreeSet

Hi all,

I've got an error when I look up my lazy loaded children of one of my pojos:

java.lang.ClassCastException: org.eclipse.persistence.indirection.IndirectSet cannot be cast to java.util.TreeSet

Ok, the thing has something to do with the lazy loading technology in EclipseLink/TopLink... if i have an entity like this:

@Entity
class Entity {

@OneToMany (mappedBy = "entity", fetch=FetchType.LAZY, cascade = {CascadeType.ALL})
private Set<Child> childrens = new TreeSet<Child>();

public void setChildrens(Set<Child> childrens) { this.childrens = childrens }

public Set<Child> getChildrens() { return this.childrens }

public Child getNextChild() {
return this. childrens.size() > 0 ? ((TreeSet<Child>) this. childrens).last() : null;
}
...
}

If I now find all entities of Entity and call getNextChild(), I will get the error. It seems that EclipseLink will pass a IndirectSet object into my childrens set and then I can not cast it anymore. The indirect set handles somehow the lazy load technique.... so what to do?

I tried this:
public void setChildrens(Set<Child> childrens) { this.childrens = new TreeSet<Child>(childrens); }

but this does not work either. It seems, that EclipseLink is using reflection to pass the IndiretSet into my set property.

I my assumptions are correct, what is to do if want to use lazy loading, a TreeSet (for sorting purposes--see .last() above) and the Set property of my Entity class interface should be remain java.uti.Set?

Thank you for help!

Martin.