Drools java.lang.NullPointerException at org.drools.reteoo.RuleTerminalNode 任何想法

Question

像往常一样，这些天我正在努力研究流口水。老实说，我有很多困难，我有点气馁。现在我有这个问题。 我的应用程序必须监视何时激活磁接触以及何时必须撤回接触释放事件。反之亦然。这是我的规则和我拥有的大空指针。任何帮助将不胜感激！非常感谢！！

 rule "contact activated vs contact released"   salience 0 no-loop true
    when
        $contact_activated : Event(type == EventType.CONTACT_ACTIVATED) ||  

    $contact_released : Event(type == EventType.CONTACT_RELEASED)
        then

             if($contact_activated!= null) {
                retract($contact_activated);
             } else {
                retract($contact_released);
             }
end 

和 我有

java.lang.NullPointerException
    at org.drools.reteoo.RuleTerminalNode$SortDeclarations.compare(RuleTerminalNode.java:477)
    at org.drools.reteoo.RuleTerminalNode$SortDeclarations.compare(RuleTerminalNode.java:473)
    at java.util.Arrays.mergeSort(Arrays.java:1270)
    at java.util.Arrays.sort(Arrays.java:1210)
    at org.drools.reteoo.RuleTerminalNode.<init>(RuleTerminalNode.java:119)
    at org.drools.RuleActivationListenerFactory.createActivationListener(RuleActivationListenerFactory.java:21)
    at org.drools.reteoo.builder.ReteooRuleBuilder.addSubRule(ReteooRuleBuilder.java:157)
    at org.drools.reteoo.builder.ReteooRuleBuilder.addRule(ReteooRuleBuilder.java:123)
    at org.drools.reteoo.ReteooBuilder.addRule(ReteooBuilder.java:110)
    at org.drools.reteoo.ReteooRuleBase.addRule(ReteooRuleBase.java:441)
    at org.drools.common.AbstractRuleBase.addRule(AbstractRuleBase.java:821)
    at org.drools.common.AbstractRuleBase.addPackages(AbstractRuleBase.java:555)
    at org.drools.reteoo.ReteooRuleBase.addPackages(ReteooRuleBase.java:458)
    at org.drools.impl.KnowledgeBaseImpl.addKnowledgePackages(KnowledgeBaseImpl.java:150)
    at it.ipiu.pch.sel.RuleTest.before(RuleTest.java:1272)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:27)
    at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:31)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:76)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:49)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

Answer 1

这看起来像一个错误，我建议您向项目提交一个 JIRA。你用的是哪个版本？

同时，您的规则比应有的复杂。每次你在结果中看到一个“如果”，这是一个危险信号，有些事情不好。您可以将规则重写为：

rule "contact activated vs contact released"
when
    $contact : Event( type in ( EventType.CONTACT_ACTIVATED, EventType.CONTACT_RELEASED ) )
then
    retract($contact);
end