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JDK-6213099 : Generic Types are Not Verified Correctly

Details
Type:
Bug
Submit Date:
2004-12-30
Status:
Closed
Updated Date:
2010-04-02
Project Name:
JDK
Resolved Date:
2005-01-06
Component:
tools
OS:
linux
Sub-Component:
javac
CPU:
x86
Priority:
P4
Resolution:
Duplicate
Affected Versions:
5.0
Fixed Versions:

Related Reports
Duplicate:

Sub Tasks

Description
FULL PRODUCT VERSION :
java version "1.5.0"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0-b64)
Java HotSpot(TM) Client VM (build 1.5.0-b64, mixed mode, sharing)
p

ADDITIONAL OS VERSION INFORMATION :
Linux genhome 2.6.9-gentoo-r12 #1 SMP Sat Dec 25 09:36:48 WET 2004 i686 Intel(R) Pentium(R) 4 CPU 1.80GHz GenuineIntel GNU/Linux

EXTRA RELEVANT SYSTEM CONFIGURATION :
Eclipse 3.1 M4

A DESCRIPTION OF THE PROBLEM :
I created a class called TransformEnum<S,D>:

S - Source Type
D - Destination Type

this class basically accepts an java.util.Enumeration<S>()

and enumerates on those elements that are of Type D:

I had the Following Problem:

When I created an TransformEnum<Node,NodeCategory> where
Node (is an interface - base class)
and NodeCategory is a derived class (further down the tree)

part of the code is as follows:

  protected D getNextElement()
  {
    D oReturn = null;
    S oTemp;
    while (m_oWrapped.hasMoreElements())
    {
      oTemp = m_oWrapped.nextElement();
      if (m_oFilter != null)
      {
        if (!m_oFilter.pass(oTemp))
        { // Failed Filter

          continue;
        }
      }

      if (m_oTransform != null)
      {
        oReturn = m_oTransform.transform(oTemp);
        if (oReturn != null)
        { // Object Transformed

          break;
        }
      }
      else
      {
        try
        {
(*)       oReturn = (D) oTemp;

          break;
        }
        catch (ClassCastException e)
        {
          continue;
        }
      }
    }

    return oReturn;
  } // end method getNextElement

On the line marked (*) I'm casting oTemp to Type (D).

What is happening:

the wrapped enumerator is returning an Object of Type StandardValueNode (a class that implements the Node Class) : Tree Something Like

Node
 |
AbstractNode
 |
AbstractValueNode
 |
StandardValueNode

and casts it to D

Whose Tree is Something Like:

Node
  |
AbstractNode
  |
AbstractBrowserNode
  |
.....
  |
NodeCategory

without throwing the expected ClassCastException:

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
I expect that the cast should throw the exception (as Expected)

Tried:  oTemp instanceof D - Compile Error : cannot perform instanceof check against type parameter D

Tried:  oReturn.getClass().cast(oTemp); - Compile Error : cannot convert from ? extends Object to D


ACTUAL -
No exception is thrown and my code crashes somewhere else

REPRODUCIBILITY :
This bug can be reproduced always.
###@###.### 2004-12-30 06:19:18 GMT

                                    

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