prashanth Reddy Dundigal [https://community.jboss.org/people/prashanth_biomorf] created the discussion "Getting error while working with "request" example in jBPM" To view the discussion, visit: https://community.jboss.org/message/753458#753458 -------------------------------------------------------------- Hi, When I run the request example, for dynamically adding the ad-hoc rule, it gives me the below error. The code is exactly the same given in example. What we need to change in order to execute it correctly. I see that it is not printing what is there in the "adhoc.drl", so obviously adhoc rule is not invoked. I get the error at the line "ksession.getKnowledgeBase().addKnowledgePackages(kbuilder.getKnowledgePackages());" Exception in thread "AWT-EventQueue-0" java.lang.RuntimeException: unable to invoke method: org.jbpm.examples.request.Request.getId: target of method is null           at org.mvel2.optimizers.impl.refl.nodes.GetterAccessor.getValue(GetterAccessor.java:66)           at org.mvel2.optimizers.impl.refl.nodes.VariableAccessor.getValue(VariableAccessor.java:37)           at org.mvel2.ast.ASTNode.getReducedValueAccelerated(ASTNode.java:108)           at org.mvel2.ast.BinaryOperation.getReducedValueAccelerated(BinaryOperation.java:107)           at org.mvel2.MVELRuntime.execute(MVELRuntime.java:85)           at org.mvel2.compiler.CompiledExpression.getValue(CompiledExpression.java:123)           at org.mvel2.MVEL.executeExpression(MVEL.java:930)           at org.drools.rule.constraint.MvelConditionEvaluator.evaluate(MvelConditionEvaluator.java:70)           at org.drools.rule.constraint.MvelConditionEvaluator.evaluate(MvelConditionEvaluator.java:49)           at org.drools.rule.constraint.MvelConstraint.evaluate(MvelConstraint.java:167)           at org.drools.rule.constraint.MvelConstraint.isAllowedCachedLeft(MvelConstraint.java:136)           at org.drools.common.SingleBetaConstraints.isAllowedCachedLeft(SingleBetaConstraints.java:130)           at org.drools.reteoo.FromNode.updateSink(FromNode.java:473)           at org.drools.reteoo.RuleTerminalNode.attach(RuleTerminalNode.java:344)           at org.drools.reteoo.builder.ReteooRuleBuilder.addSubRule(ReteooRuleBuilder.java:168)           at org.drools.reteoo.builder.ReteooRuleBuilder.addRule(ReteooRuleBuilder.java:128)           at org.drools.reteoo.ReteooBuilder.addRule(ReteooBuilder.java:116)           at org.drools.reteoo.ReteooRuleBase.addRule(ReteooRuleBase.java:445)           at org.drools.common.AbstractRuleBase.addRule(AbstractRuleBase.java:956)           at org.drools.common.AbstractRuleBase.addPackages(AbstractRuleBase.java:627)           at org.drools.reteoo.ReteooRuleBase.addPackages(ReteooRuleBase.java:472)           at org.drools.impl.KnowledgeBaseImpl.addKnowledgePackages(KnowledgeBaseImpl.java:150)           at org.jbpm.examples.request.RequestUI.addRules(RequestUI.java:238)           at org.jbpm.examples.request.RequestUI.access$3(RequestUI.java:229)           at org.jbpm.examples.request.RequestUI$4.actionPerformed(RequestUI.java:182)           at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)           at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)           at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)           at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)           at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)           at java.awt.Component.processMouseEvent(Component.java:6263)           at javax.swing.JComponent.processMouseEvent(JComponent.java:3255)           at java.awt.Component.processEvent(Component.java:6028)           at java.awt.Container.processEvent(Container.java:2041)           at java.awt.Component.dispatchEventImpl(Component.java:4630)           at java.awt.Container.dispatchEventImpl(Container.java:2099)           at java.awt.Component.dispatchEvent(Component.java:4460)           at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4574)           at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4238)           at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4168)           at java.awt.Container.dispatchEventImpl(Container.java:2085)           at java.awt.Window.dispatchEventImpl(Window.java:2475)           at java.awt.Component.dispatchEvent(Component.java:4460)           at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)           at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)           at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)           at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)           at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)           at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)           at java.awt.EventDispatchThread.run(EventDispatchThread.java:122) Caused by: java.lang.NullPointerException           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.mvel2.optimizers.impl.refl.nodes.GetterAccessor.getValue(GetterAccessor.java:43)           ... 49 more Can you please see it and let us know what to do. Thank you in advance, Warmest regards, Prashanth Reddy Dundigal -------------------------------------------------------------- Reply to this message by going to Community [https://community.jboss.org/message/753458#753458] Start a new discussion in jBPM Development at Community [https://community.jboss.org/choose-container!input.jspa?contentType=1&...]