[rules-users] IllegalAccessError in shadow classes

[Edson Tirelli]

   Drools tries to create the ShadowProxy. The reason is that it does not
know about the implementation... it just knows it is a Map and as so, it
must be shadowed. Problem is that SingletonMap is either  final or does not
have a default constructor.
   My recommendation, besides opening a JIRA for this, is avoid inserting
collections/maps directly as facts. The semantic for such facts is not
clearly defined and it may cause undesired behavior.

   []s
   Edson

2008/2/19, Godmar Back <godmar at gmail.com>:
>
> Hi,
>
> usings Drools 4.0.4 and MVEL 1.4, this simple rule:
> ---
> package test;
>
> import java.util.Collections;
>
> dialect "mvel"
>
> rule "Rule #1"
> when
> then
>     insert(Collections.singletonMap("content", "hello"));
> end
> --
>
> produces:
> java.lang.IllegalAccessError: class
> org.drools.shadow.java.util.Collections$SingletonMapShadowProxy cannot
> access its superclass java.util.Collections$SingletonMap
>         at java.lang.ClassLoader.defineClass1(Native Method)
>         at java.lang.ClassLoader.defineClass(ClassLoader.java:620)
>         at org.drools.rule.MapBackedClassLoader.fastFindClass(
> MapBackedClassLoader.java:60)
>         at org.drools.rule.MapBackedClassLoader.loadClass(
> MapBackedClassLoader.java:79)
>         at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
>         at org.drools.reteoo.Rete$ClassObjectTypeConf.loadOrGenerateProxy(
> Rete.java:547)
>         at
> org.drools.reteoo.Rete$ClassObjectTypeConf.defineShadowProxyData(Rete.java
> :494)
>         at org.drools.reteoo.Rete$ClassObjectTypeConf.<init>(Rete.java
> :461)
>         at org.drools.reteoo.Rete.assertObject(Rete.java:152)
>         at org.drools.reteoo.ReteooRuleBase.assertObject(
> ReteooRuleBase.java:192)
>         at org.drools.reteoo.ReteooWorkingMemory.doInsert(
> ReteooWorkingMemory.java:71)
>         at org.drools.common.AbstractWorkingMemory.insert(
> AbstractWorkingMemory.java:909)
>         at org.drools.common.AbstractWorkingMemory.insert(
> AbstractWorkingMemory.java:881)
>         at org.drools.base.DefaultKnowledgeHelper.insert(
> DefaultKnowledgeHelper.java:67)
>         at org.drools.base.DefaultKnowledgeHelper.insert(
> DefaultKnowledgeHelper.java:61)
>
>
> It's not clear to me why Drools creates Proxies for such classes as
> java.util.Collections, or does MVEL do it?
>
> - Godmar
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>



-- 
  Edson Tirelli
  JBoss Drools Core Development
  Office: +55 11 3529-6000
  Mobile: +55 11 9287-5646
  JBoss, a division of Red Hat @ www.jboss.com
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