Remote object trying to return another remote object and a ClassCastExcepti

Question

I have a server running with a TreeModel (the tree model implements Remote). I also have the the TreeNodes all linked together on the server. Now, I can get to the TreeModel on the server and the root node of the remote tree model.
treeModelStub = (treeModelIface)Naming.lookup(url+"remoteTM"); //works
rootStub = (remoteTreeNodeIface)treeModelStub.getRoot(); //works. The call to getRoot returns Object
But when I call
remoteTreeNodeIface aChild = (remoteTreeNodeIface)rootStub.getChildAt(index) //Does not work. "Exception in thread "main" java.lang.ClassCastException
at remoteTreeNode_Stub.getChildAt(Unknown Source)
The remote tree node method getChildAt returns TreeNode because the class implements TreeNode:
public class remoteTreeNode extends UnicastRemoteObject implements rdcaDataIface, Comparable, TreeNode {
public TreeNode getChildAt(int idx) {
System.out.println("DEBUG: class is "+this.getClass()); // class is remoteTreeNode
return (remoteTreeNode)children.get(idx);
The remote interface is defined as:
public interface rdcaDataIface extends java.rmi.Remote {
public TreeNode getChildAt(int idx) throws RemoteException;
Any ideas why this does not work. Why can a remote object of type Object be returned just fine, but a TreeNode not be returned?
Thank you for your help,
Brent

Answer 1

I have a server running with a TreeModel (the tree
model implements Remote). I also have the the
TreeNodes all linked together on the server. Now, I
can get to the TreeModel on the server and the root
node of the remote tree model.
treeModelStub =
(treeModelIface)Naming.lookup(url+"remoteTM");
//works
rootStub =
(remoteTreeNodeIface)treeModelStub.getRoot();
//works. The call to getRoot returns Object
But when I call
remoteTreeNodeIface aChild =
(remoteTreeNodeIface)rootStub.getChildAt(index)******************************************
can only be casted to rdcaDataIface. The returned object is an instanceof the rdcaDataIface_stub, which have nothing to do with TreeNode.
//Does not work. "Exception in thread "main"
java.lang.ClassCastException
at remoteTreeNode_Stub.getChildAt(Unknown
t(Unknown Source)
The remote tree node method getChildAt returns
TreeNode because the class implements TreeNode:
public class remoteTreeNode extends
UnicastRemoteObject implements rdcaDataIface,
Comparable, TreeNode {
public TreeNode getChildAt(int idx) {
System.out.println("DEBUG: class is
lass is "+this.getClass()); // class is
remoteTreeNode
return (remoteTreeNode)children.get(idx);
The remote interface is defined as:
public interface rdcaDataIface extends java.rmi.Remote
public TreeNode getChildAt(int idx) throws
ows RemoteException;
Any ideas why this does not work. Why can a remote
object of type Object be returned just fine, but a
TreeNode not be returned?
Thank you for your help,
Brent