topic Re: calling getter inside method Returns java.lang.NullPointerException with Activiti Engine in Alfresco Forum

calling getter inside method Returns java.lang.NullPointerException with Activiti Engine

ilyass_act — Wed, 03 May 2017 11:21:09 GMT

i'm tryin to implement my own java logic using SPRING + JSF with activiti , this my BPMN file :<?xml version="1.0" encoding="UTF-8"?><definitions xmlns="http://www.omg.org/spec/BPMN/20100524/MODEL" targetNamespace="http://www.bpmnwithactiviti.org" xmlns:activiti="http://activiti.org/bpmn"&g

Re: calling getter inside method Returns java.lang.NullPointerException with Activiti Engine

gdharley — Wed, 03 May 2017 20:07:48 GMT

Is bookOrder registered as a bean?

Thx,

Greg

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Re: calling getter inside method Returns java.lang.NullPointerException with Activiti Engine

ilyass_act — Thu, 04 May 2017 14:05:44 GMT

yes in my activiti.cfg.xml :

<bean id="bookOrder" class="ma.net.s2m.selectsystem.web.controller.admin.BookOrder" />
<bean id="operationController" class="ma.net.s2m.selectsystem.web.controller.admin.OperationController"/>
<bean id="adminModele" class="ma.net.s2m.selectsystem.web.modele.AdminModele"/>
</beans>

Re: calling getter inside method Returns java.lang.NullPointerException with Activiti Engine

gdharley — Thu, 04 May 2017 14:49:51 GMT

Good start. Now the stack trace and source code would be helpful

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Re: calling getter inside method Returns java.lang.NullPointerException with Activiti Engine

ilyass_act — Thu, 04 May 2017 15:20:36 GMT

public void getProcessDiagram() {
ProcessEngine processEngine = ProcessEngineConfiguration.createProcessEngineConfigurationFromResource("activiti.cfg.xml").buildProcessEngine();

RuntimeService runtimeService = processEngine.getRuntimeService();
RepositoryService repositoryService = processEngine.getRepositoryService();
TaskService taskService = processEngine.getTaskService();
FormService formService = processEngine.getFormService();
IdentityService service = processEngine.getIdentityService();

// Deploy the process definition
Deployment deployment = repositoryService.createDeployment()
.addClasspathResource("processesT.bpmn20.xml")
.deploy();

// Start a process instance
ProcessInstance processInstance = runtimeService.startProcessInstanceByKey("my-process");

// here i test the sayHello() ===> it displays the bookOrder.getIsbn() value
sayHello() ;

List<org.activiti.engine.task.Task> taskes = taskService.createTaskQuery().processInstanceId(processInstance.getId()).list();

System.out.println("List size: " + taskes.size());

for (org.activiti.engine.task.Task task : taskes) {
System.out.println("Task available: " + task.getName());
System.out.println("Task assignee :"+task.getAssignee());

}

org.activiti.engine.task.Task task = taskes.get(0);
Map<String , Object> taskVariables = new java.util.HashMap<String,Object>() ;
taskVariables.put("vacationApproved", "false");
taskVariables.put("managerMotivation", "We have a tight deadline!");
List<String>list = runtimeService.getActiveActivityIds(exec.getId());
for(String task1 : list){
System.out.println("****************************** Current Task : "+task1);
System.out.println("****************************** Description : "+taskes.get(0).getDescription());

System.out.println("Number of process instances: " + runtimeService.createProcessInstanceQuery().count());
}
taskService.complete(task.getId(), taskVariables);

----------------------------------------------------------------------------------------------- Error----------------------------------------
Caused by: org.activiti.engine.impl.javax.el.ELException: java.lang.NullPointerException
at org.activiti.engine.impl.javax.el.BeanELResolver.invoke(BeanELResolver.java:487)
at org.activiti.engine.impl.javax.el.CompositeELResolver.invoke(CompositeELResolver.java:397)
at org.activiti.engine.impl.juel.AstMethod.invoke(AstMethod.java:102)
at org.activiti.engine.impl.juel.AstMethod.eval(AstMethod.java:86)
at org.activiti.engine.impl.juel.AstEval.eval(AstEval.java:50)
at org.activiti.engine.impl.juel.AstNode.getValue(AstNode.java:26)
at org.activiti.engine.impl.juel.TreeValueExpression.getValue(TreeValueExpression.java:114)
at org.activiti.engine.impl.delegate.ExpressionGetInvocation.invoke(ExpressionGetInvocation.java:33)
at org.activiti.engine.impl.delegate.DelegateInvocation.proceed(DelegateInvocation.java:37)
at org.activiti.engine.impl.delegate.DefaultDelegateInterceptor.handleInvocation(DefaultDelegateInterceptor.java:25)
at org.activiti.engine.impl.el.JuelExpression.getValue(JuelExpression.java:48)
... 143 more
Caused by: java.lang.NullPointerException
at ma.net.s2m.selectsystem.web.controller.admin.OperationController.sayHello(OperationController.java:898)
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.activiti.engine.impl.javax.el.BeanELResolver.invoke(BeanELResolver.java:483)
... 153 more

Re: calling getter inside method Returns java.lang.NullPointerException with Activiti Engine

gdharley — Thu, 04 May 2017 15:34:32 GMT

Im having a really hard time understanding what you are actually doing.

The following excerpt from the stack:

Caused by: java.lang.NullPointerException
at ma.net.s2m.selectsystem.web.controller.admin.OperationController.sayHello(OperationController.java:898)

Suggests you have a REST Controller called OperationController and that the exception is being thrown not when your process calls a JavaDelegate (your service task).

If this is happening during a REST call, be aware that the servlet and process dont share the same context and it is possible any bean defined in the process engine is not available to the servlet (I have seen this a number of times).

The solution is to add a helper to retrieve the process engine context. The following link will give you the details:

java - Using some beans in Filter bean class? - Stack Overflow

Cheers,

Greg

‌

Re: calling getter inside method Returns java.lang.NullPointerException with Activiti Engine

ilyass_act — Thu, 04 May 2017 15:49:50 GMT

I'm not using a RestController , but what i understand is that when Activiti process starts , Activiti creats it's own new context so my objects which were full in my context becomes null in activiti context since i can call sayHello () and i don't get an error but when sayHello() is called via activiti:expression="#{operationController.sayHello()}" it tells me that my object is null !!

Re: calling getter inside method Returns java.lang.NullPointerException with Activiti Engine

gdharley — Thu, 04 May 2017 15:57:33 GMT

Honestly, I dont understand what you are trying to do. In order to make any progress a unit test is in order.

Sorry,

Greg

Re: calling getter inside method Returns java.lang.NullPointerException with Activiti Engine

ilyass_act — Thu, 04 May 2017 16:56:37 GMT

what i'm tryin to do is binding my objects to workflow , for example activiti:expression="#{operationController.sayHello()" e this method returns NullPointerException , but my object is not Null because i already did bookOrder.setIsbn("123") before , i tried with a simple String test ="test" when i pass it to the sayHello() it doesn't return NPE the problem is everytime i pass value with Setter or try to get value with getter sayHello return NPE for that object.

hope i'm someHow clear .
regards

Re: calling getter inside method Returns java.lang.NullPointerException with Activiti Engine

ilyass_act — Fri, 05 May 2017 07:49:44 GMT

Hi Greg ,
is there a better way of declaring my beans so they can be detetcted from my BPMNfile ?

Re: calling getter inside method Returns java.lang.NullPointerException with Activiti Engine

gdharley — Fri, 05 May 2017 11:54:35 GMT

Nope, these are simple spring beans and need to be declared in the spring context.

Re: calling getter inside method Returns java.lang.NullPointerException with Activiti Engine

ilyass_act — Fri, 05 May 2017 13:01:06 GMT

For example @Service("bookOrder") won't work ?

Re: calling getter inside method Returns java.lang.NullPointerException with Activiti Engine

gdharley — Fri, 05 May 2017 14:50:33 GMT

If you're using spring annotation based configuration then this is what you would do.

If you are using xml based configuration (which is what it appears you are doing) then you would use the activiti.cfg.xml

Re: calling getter inside method Returns java.lang.NullPointerException with Activiti Engine

ilyass_act — Fri, 05 May 2017 15:48:18 GMT

Thank you Geg ,
Let's say you have a ServiceTask where you pass expression , activiti:expression="${operationController.sayHello()}" .
and your method implements something like this :
public void sayHello(){

System.out.println("the isbn :"+bookOrder.getIsbn());

}

the value of ISBN comes from a JSF Form , How would you implement this ?