Java casting / classloader issues

Question

Here is the simplified version of the problem:

 SomeClass c = (SomeClass) obj.getSomeClassParent()

not always but it happens sometimes to t

Answer 1

I think it can happen if

1. a SomeClass instance was loaded from ClassLoader X (so its class is SomeClass of CL X or let's call it: CL(X).SomeClass)
2. but it is being cast in a different class loader. E.g. the current Threads class loader is Y so SomeClass is actually CL(Y).SomeClass

So you have:

• instance class = CL(X).SomeClass
• class cast target = CL(Y).SomeClass

Or in other words - not the same class - thus the class cast exception.

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Possible duplicate of: ClassCastException when casting to the same class - it has some good suggestions as well.