Question

像往常一样，我正在努力学习流口水。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性触点以及何时触发释放事件必须缩回。反之亦然。这是我的规则和我的大空指针。任何帮助将非常感谢！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bug，我建议你向项目提交一个JIRA。你使用的是哪个版本？

与此同时，你的规则比它应该更加复杂。每当你在结果中看到“如果”时，它就是一面红旗，这是不好的。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

在org.drools.reteoo.RuleTerminalNode任何想法下drools java.lang.NullPointerException

1 个答案: