[Tm4j-developers] [ tm4j-Bugs-1501213 ] MemberImpl.hashCode() is not consistent with equals()

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Bugs item #1501213, was opened at 2006-06-05 22:23
Message generated for change (Comment added) made by lheuer
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Category: In-Memory Impl
Group: CVS
>Status: Closed
Resolution: None
Priority: 5
Private: No
Submitted By: Xuan Baldauf (mediumnet)
Assigned to: Nobody/Anonymous (nobody)
Summary: MemberImpl.hashCode() is not consistent with equals()

Initial Comment:
When the constructor
org.tm4j.topicmap.memory.MemberImpl( AssociationImpl
parent, String id, Locator resourceLoc, Topic roleSpec,
Collection players) is used,

the to-be-constructed MemberImpl adds itself to each
m_rolesPlayed field of every TopicImpl of the players
collection. This field is a HashSet, and thus,
hashCode() of the MemberImpl object is called. The
method hashCode() (defined in
org.tm4j.topicmap.memory.TopicMapObjectImpl) itself
depends on the id of the MemberImpl object. However,
the id is currently set ("setID(id);") _after_ the
to-be-constructed MemberImpl adds itself to each
m_rolesPlayed field of every TopicImpl of the players
collection.

Thus, hashCode() returns different values at different
times (with a very high probability). In particular,
hashCode() returns a different value before the call to
setID(id) than after the call to setID(id).

This, in turn, makes the call
"m_rolesPlayed.contains(member)" in
org.tm4j.topicmap.memory.TopicImpl.removeRolePlayed(Member
member) return false, while it should return true.

>From this on, the topic map data structure is
inconsistent (and messed up).


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>Comment By: Lars Heuer (lheuer)
Date: 2007-02-15 15:57

Message:
Logged In: YES 
user_id=399396
Originator: NO

Fixed in CVS. Thanks

----------------------------------------------------------------------

Comment By: Xuan Baldauf (mediumnet)
Date: 2006-06-05 22:25

Message:
Logged In: YES 
user_id=506885

This patch should fix the problem:

Index: tm4j/src/org/tm4j/topicmap/memory/MemberImpl.java
===================================================================
RCS file:
/cvsroot/tm4j/tm4j/src/org/tm4j/topicmap/memory/MemberImpl.java,v
retrieving revision 1.24
diff -u -r1.24 MemberImpl.java
--- tm4j/src/org/tm4j/topicmap/memory/MemberImpl.java   7
Mar 2006 15:36:35 -0000       1.24
+++ tm4j/src/org/tm4j/topicmap/memory/MemberImpl.java   5
Jun 2006 20:08:49 -0000
@@ -56,14 +56,14 @@
         m_roleSpec = roleSpec;
         m_players = new ArrayList(players);

+        if (resourceLoc != null) addSourceLocator(resourceLoc);
+        setID(id);
         for (Iterator it = m_players.iterator();
it.hasNext();) {
             TopicImpl t = (TopicImpl) it.next();
             // TODO: Avoid the access of the
Topic.m_rolesPlayed field
             t.m_rolesPlayed.add(this);
         }

-        if (resourceLoc != null) addSourceLocator(resourceLoc);
-        setID(id);
         parent.addMember(this);
     }



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