ravana ravana - 1 month ago 20
Java Question

Solution for the ClassCastException due to ClassLoader issue

I have two ClassLoaders which loads the same class. So, obviously these can't cast to one another. But I need to access an object created in the other ClassLoader.

I have access to both ClassLoaders. How can I use that object in the other class? I don't need to cast the object to match to the current ClassLoader.

But the issue is that the returned object's type is

Object
. So, I have to cast down that object to access some methods. How can I do that? Normal cast like the following causes ClassCastException, which I already know.

Mojo mojo = (Mojo) descriptor.getMojo();


descriptor#getMojo()
returns an object of type
Mojo
but the method returns
Object
. How can do this?

Let me know if you need further info.

I've read all the theories about classloading, but none has specified a proper solution for this.

Answer Source

AFAIK, no, you can't cast an object of a class loaded by one class-loader in another class loader.

  • One solution would be to create a "common" class-loader which loads the classes to be used by your custom classloaders. So in your case, you'd have a new classloader which would load the given class and your custom classloaders would extend this classloader.
  • Another solution would be to pass around the "serialized" state between the two classloaders. Serialize one instance to a byte array and reconstruct the object in the other classloader by de-serializing the object stream.