Need Help In ClassCastException

jagadesh · **Joined:** Sat Apr 26, 2008 12:16 pm **Posts:** 5

while i was working with the oneToMany Releationship , i was getting
an exception as

java.lang.ClassCastException: org.hibernate.collection.PersistentBag
cannot be cast to java.util.ArrayList

this arrives when i try to get the list of objects .

Can u Plz Provide Me the Solution

njr28 · **Joined:** Fri Mar 30, 2007 5:57 am **Posts:** 5

Hi,

What's the code in your persistent class?

Is it something like:

Code:

public class Example {

    private ArrayList anExampleList;

    public void setAnExampleList(ArrayList anExampleList) {
        this.anExampleList = anExampleList;
    }

    public ArrayList getAnExampleList() {
        return this.anExampleList;
    }
}

Neil

Sukirtha · **Posted:** Tue May 13, 2008 4:08 am

Looks like you are using a Bag in your mapping file for one-to-many relationship whereas you are trying to assign it to an ArrayList.

Make sure your java bean is in sync with the mapping file.

madtyn · **Joined:** Sun Aug 23, 2009 8:09 am **Posts:** 9

"org.hibernate.collection.PersistentBag cannot be cast to java.util.ArrayList"

I have exactly this same message using annotations when I try to access a List<Object> I have on one of my classes. I had no problems using the List Interface collections until now.

The code is this:

Code:

e.estEmps = (List<EstEmp>)((ArrayList<EstEmp>)this.estEmps).clone();

The collection 'this.estEmps' is retrieved from the database, it usually works, so it's correctly mapped, but this time I needed to make a clone() of the complete List collection, so I made the cast to ArrayList and found that it throwed an exception.

I need to return a List for the assignment on the left side, so I don't mind changing the Collection, but I never used the PersistentBag and don't know how to handle in order to get a Collection implementing the List interface. I looked the reference and didn't find anything returning List.

Please help!

madtyn · **Joined:** Sun Aug 23, 2009 8:09 am **Posts:** 9

I have done my homework and read the Manning and I found that if I want to use a List and not to be used as a PersistentBag by Hibernate I have to initialize as

List<MyObject> = new ArrayList<MyObject>();

and use the annotation

@org.hibernate.annotations.IndexColumn(name="INDEXCOLUMN")

My problem is that I don't have this column not anything similar on my database (unless I use my composite Id to make an index, which would be too strange...). Should I change to another Collection like Set? I wouldn't mind because I don't have any important order or sort method, but I don't know if clone() will work the same or if there are other disadvantages.

Could anyone give me some advice, please?

EDIT: I've tried the same using the Set interface and the HashSet Implementation. No changes. This is the exception.

org.hibernate.collection.PersistentSet cannot be cast to java.util.HashSet

Cameron McKenzie · **Posted:** Thu Aug 27, 2009 9:09 am

Is this in a distributed environment by any chance? Is it the web end that is getting this problem?

madtyn · **Joined:** Sun Aug 23, 2009 8:09 am **Posts:** 9

This is happening in a web application which I'm developing in my laptop. I'm a student at the faculty. The fact is that everything is running on a single computer which is this laptop.

The error appears through the web as a Tapestry exception pointing to the Hibernate cause of not being able to cast th persistent bag to an ArrayList when I try to clone() the estEmps List, which should be an ArrayList, as I initialized in the source code.

I don't know if that answers to your question. Maybe my understanding of English is not enough.

TS · **Joined:** Sun Apr 06, 2008 8:49 am **Posts:** 3

The following should get you around the org.hibernate.collection.PersistentSet cannot be cast to java.util.HashSet error (obviously you'll need to change object/method names to match your project):

Set<YourObject> aSet = new HashSet<YourObject>();
aSet.addAll((Set) modelObject.getSetOfObjects());

guicpv · **Joined:** Fri Sep 18, 2009 11:21 pm **Posts:** 2

EDIT: I was wrong.

nandoztx · **Joined:** Fri Oct 14, 2011 8:07 am **Posts:** 1

if you need, you can iterate your list like as:

Code:

for(Object o : yourListObject){
  o.myProperty();
}

without convert or cast to anything...