CODEWITHSUNDEEP
javajpatypesclasscastexception
Sergey
Sergey

Reputation: 21

weird class cast exception

I can't understand why i've got ClassCastException at the last row of code
I thought if i had OrgStructure list parametrised - there will be no problem

List<MqtAsutrOrgst2> OrgStructure = null;
    Query query = null;
    ...
            ...

    OrgStructure = query.getResultList();       
    for (Object o : OrgStructure) {

        MqtAsutrOrgst2 orgStructureItem = (MqtAsutrOrgst2) o;

    }

p.s. MqtAsutrOrgst2 is just an @Entity

Upvotes: 0

Views: 744

Answers (4)

Sergey
Sergey

Reputation: 21

so finally problem was caused by missing one of the fields in materialised query table which was mapped on MqtAsutrOrgst2 class
thanx all

Upvotes: 0

artplastika
artplastika

Reputation: 1982

I suppose that MqtAsutrOrgst2 is a subclass of OrgStructure. Seems you get list of OrgStructure using JPA. We need more information on Query object that you use. But most likely you use Query that constructs exactly objects of superclass OrgStructure.

Upvotes: 0

AllTooSir
AllTooSir

Reputation: 49402

I can't understand why i've got ClassCastException at the last row of code

What I understand is MqtAsutrOrgst2 is subclass or implementation type of OrgStructureItemType class . The List orgstructItems is defined to keep anything that is a sub type of OrgStructureItemType which includes MqtAsutrOrgst2 and probably some other sub classes as well which cannot be casted between one another.

MqtAsutrOrgst2 orgStructureItem = (MqtAsutrOrgst2) o;

You are forcing the compiler to believe that at runtime the object o will be an object of MqtAsutrOrgst2 , but actually it is an object of some other sub class of OrgStructureItemType which cannot be cast to MqtAsutrOrgst2.

There are better ways to do this , but you can do a temporary fix :

if(o instanceof MqtAsutrOrgst2)     
  MqtAsutrOrgst2 orgStructureItem = (MqtAsutrOrgst2) o;

The below code will be a quick fail :

for (MqtAsutrOrgst2 o : OrgStructure) { ... }

Upvotes: 2

Piotr Idzikowski
Piotr Idzikowski

Reputation: 723

Just try to log the type of the object and everything should be clear

Upvotes: 1

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