Error Rendering View[dummy.xhtml]: java.lang.NullPointerException

Question

I'm pretty new to JSF and recently I get this error, which I couldn't manage to solve. My intention was to open a dialog which has a picklist in it to select from the list and reload the datatable with the chosen elements.

:

13:47:22,873 SEVERE [javax.enterprise.resource.webcontainer.jsf.context] (default task-72) javax.faces.component.UpdateModelException: javax.el.PropertyNotWritableException: /forms/bestellungLieferant.xhtml @29,29 value="#{bestellungLieferantController.getAllAvailableKomponentDualListModel()}": Illegal Syntax for Set Operation

My JSF Page:

<!DOCTYPE HTML>
<html lang="en" xmlns="http://www.w3.org/1999/xhtml"
    xmlns:ui="http://java.sun.com/jsf/facelets"
    xmlns:h="http://java.sun.com/jsf/html"
    xmlns:f="http://java.sun.com/jsf/core"
    xmlns:p="http://primefaces.org/ui">

<f:view>
    <f:metadata>
        <!-- Start working on a task. Task Id is read internally from
         request parameters and cached in the CDI conversation scope.
    -->

        <f:event type="preRenderView"
            listener="#{camundaTaskForm.startTaskForm()}" />
    </f:metadata>
    <h:head>
        <title>Paket zusammenstellen</title>
    </h:head>
    <h:body>
        <p:dialog id="komponentenAuswahlDialog" header="Komponenten auswählen"
            widgetVar="komponentenAuswahlDialog" modal="true" height="auto"
            width="auto" immediate="true" rendered="true">
            <p:pickList converter="entityConverter"
                id="komponenteAuswahlPickList"
                value="#{bestellungLieferantController.getAllAvailableKomponentDualListModel()}"
                var="komponente" itemLabel="#{komponente.serienNummer}"
                itemValue="#{komponente.id}" showSourceFilter="true"
                showTargetFilter="true">
                <f:facet name="sourceCaption">Quelle</f:facet>
                <f:facet name="targetCaption">Ziel</f:facet>
            </p:pickList>
            <h:form>
                <p:commandButton update="komponenteTable" value="Auswahl speichern"
                    oncomplete="PF('komponentenAuswahlDialog').hide();" />
            </h:form>
        </p:dialog>
        <h:panelGrid id="paketInformationPG" columns="2" border="1">
            <f:facet name="header">
                <h:outputText value="Paket zusammenstellen" />
            </f:facet>
            <h:outputLabel value="Kunde:" />
            <h:outputText value="#{processVariables['kunde']}" />

            <h:outputLabel value="Betriebssystem:" />
            <h:outputText value="Platzhalter" />

            <h:outputLabel value="Benutzer:" />
            <h:outputText value="#{processVariables['benutzerName']}" />
        </h:panelGrid>
        <h:panelGrid id="komponentenZusammenstellungPG" columns="2" border="1">
            <f:facet name="header">
                <h:panelGrid columns="2">
                    <h:outputText value="Komponenten" />
                    <h:commandButton type="button"
                        onclick="PF('komponentenAuswahlDialog').show();" value="+" />
                </h:panelGrid>
            </f:facet>
            <p:dataTable id="komponenteTable" widgetVar="komponenteTable"
                var="komponente"
                value="#{bestellungLieferantController.komponentenList}">
                <p:column>
                    <f:facet name="header">Typ</f:facet>
                    <h:outputText value="#{komponente.produkt.typ.name}" />
                </p:column>

                <p:column>
                    <f:facet name="header">Bezeichnung</f:facet>
                    <h:outputText value="#{komponente.produkt.name}" />
                </p:column>

                <p:column>
                    <f:facet name="header">SN</f:facet>
                    <h:outputText value="#{komponente.serienNummer}" />
                </p:column>

                <p:column headerText="Kaufdatum">
                    <f:facet name="header">Kaufdatum</f:facet>
                    <h:outputText value="#{komponente.bestellDatum}" />
                </p:column>

                <p:column>
                    <f:facet name="header">Aktion</f:facet>
                    <p:commandLink value="Bearbeiten" />
                    <p:commandLink value="Enfernen" />
                </p:column>
            </p:dataTable>
        </h:panelGrid>
    </h:body>
</f:view>
</html>

My Controller:

@ManagedBean
@SessionScoped
public class BestellungLieferantController implements Serializable{

    @EJB
    private BestellungFacade bestellungFacade;

    @EJB
    private PaketFacade paketFacade;

    @EJB
    private KomponenteFacade komponenteFacade;

    @EJB
    private BetriebssystemFacade betriebssystemFacade;

    // Komponent-List with added komponent items
    private List<Komponente> komponentenList = new ArrayList<Komponente>();

    private DualListModel<Komponente> komponentenDualListModel;

    public DualListModel<Komponente> getKomponentenDualListModel() {
        return komponentenDualListModel;
    }

    public void setKomponentenDualListModel(DualListModel<Komponente> komponentenDualListModel) {
        this.komponentenDualListModel = komponentenDualListModel;
    }

    public List<Komponente> getKomponentenList() {
        return komponentenList;
    }

    public void setKomponentenList(List<Komponente> komponentenList) {
        LogManager logManager = LogManager.getLogManager();
        Logger rootLogger = logManager.getLogger("DUMMY");
        rootLogger.setLevel(Level.ALL);
        rootLogger.info("KomponentenList");
        this.komponentenList = komponentenList;
    }


    /**
     * Gets the actual Model with the distinct source and 
     * @param targetList
     * @return
     */
    public DualListModel<Komponente> getAllAvailableKomponentDualListModel(){
        List<Komponente> sourceKomponenteList = this.komponenteFacade.getAllAvailableKomponente();
        List<Komponente> sourceKomponenteDistinctList = new ArrayList<Komponente>();

        if (this.komponentenList.size() != 0){
            for(Komponente k : sourceKomponenteList){
                if (!komponentenList.contains(k)){
                    sourceKomponenteDistinctList.add(k);
                }
            }
        } else {
            sourceKomponenteDistinctList = sourceKomponenteList;
        }


//      komponentenDualListModel.setSource(sourceKomponenteDistinctList);
//      komponentenDualListModel.setTarget(komponentenList);

        this.setKomponentenDualListModel(new DualListModel<Komponente>());
        this.getKomponentenDualListModel().setSource(sourceKomponenteDistinctList);
        this.getKomponentenDualListModel().setTarget(this.komponentenList);



        return this.getKomponentenDualListModel();
    }

    public void putSelectionIntoKomponenteList(){
        LogManager logManager = LogManager.getLogManager();
        Logger rootLogger = logManager.getLogger("DUMMY");
        rootLogger.setLevel(Level.ALL);
        rootLogger.info("PutSelectionIntoKomponentList");
        rootLogger.info("KOMPONENTELIST: " + komponentenDualListModel.getTarget());
        this.komponentenList = this.komponentenDualListModel.getTarget();
    }
}

My Stacktrace:

13:47:22,873 SEVERE [javax.enterprise.resource.webcontainer.jsf.context] (default task-72) javax.faces.component.UpdateModelException: javax.el.PropertyNotWritableException: /forms/bestellungLieferant.xhtml @29,29 value="#{bestellungLieferantController.getAllAvailableKomponentDualListModel()}": Illegal Syntax for Set Operation
    at javax.faces.component.UIInput.updateModel(UIInput.java:866)
    at org.primefaces.component.picklist.PickList.updateValue(PickList.java:530)
    at org.primefaces.component.picklist.PickList.validateValue(PickList.java:394)
    at javax.faces.component.UIInput.validate(UIInput.java:982)
    at org.primefaces.component.picklist.PickList.validate(PickList.java:424)
    at javax.faces.component.UIInput.executeValidate(UIInput.java:1248)
    at javax.faces.component.UIInput.processValidators(UIInput.java:712)
    at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1261)
    at org.primefaces.component.dialog.Dialog.processValidators(Dialog.java:423)
    at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1261)
    at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1261)
    at javax.faces.component.UIViewRoot.processValidators(UIViewRoot.java:1195)
    at com.sun.faces.lifecycle.ProcessValidationsPhase.execute(ProcessValidationsPhase.java:76)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
    at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:198)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:658)
    at io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:85)
    at io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:62)
    at io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36)
    at org.wildfly.extension.undertow.security.SecurityContextAssociationHandler.handleRequest(SecurityContextAssociationHandler.java:78)
    at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
    at io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:131)
    at io.undertow.servlet.handlers.security.ServletAuthenticationCallHandler.handleRequest(ServletAuthenticationCallHandler.java:57)
    at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
    at io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:46)
    at io.undertow.servlet.handlers.security.ServletConfidentialityConstraintHandler.handleRequest(ServletConfidentialityConstraintHandler.java:64)
    at io.undertow.security.handlers.AuthenticationMechanismsHandler.handleRequest(AuthenticationMechanismsHandler.java:60)
    at io.undertow.servlet.handlers.security.CachedAuthenticatedSessionHandler.handleRequest(CachedAuthenticatedSessionHandler.java:77)
    at io.undertow.security.handlers.NotificationReceiverHandler.handleRequest(NotificationReceiverHandler.java:50)
    at io.undertow.security.handlers.AbstractSecurityContextAssociationHandler.handleRequest(AbstractSecurityContextAssociationHandler.java:43)
    at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
    at org.wildfly.extension.undertow.security.jacc.JACCContextIdHandler.handleRequest(JACCContextIdHandler.java:61)
    at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
    at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
    at io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:292)
    at io.undertow.servlet.handlers.ServletInitialHandler.access$100(ServletInitialHandler.java:81)
    at io.undertow.servlet.handlers.ServletInitialHandler$2.call(ServletInitialHandler.java:138)
    at io.undertow.servlet.handlers.ServletInitialHandler$2.call(ServletInitialHandler.java:135)
    at io.undertow.servlet.core.ServletRequestContextThreadSetupAction$1.call(ServletRequestContextThreadSetupAction.java:48)
    at io.undertow.servlet.core.ContextClassLoaderSetupAction$1.call(ContextClassLoaderSetupAction.java:43)
    at io.undertow.servlet.api.LegacyThreadSetupActionWrapper$1.call(LegacyThreadSetupActionWrapper.java:44)
    at io.undertow.servlet.api.LegacyThreadSetupActionWrapper$1.call(LegacyThreadSetupActionWrapper.java:44)
    at io.undertow.servlet.api.LegacyThreadSetupActionWrapper$1.call(LegacyThreadSetupActionWrapper.java:44)
    at io.undertow.servlet.api.LegacyThreadSetupActionWrapper$1.call(LegacyThreadSetupActionWrapper.java:44)
    at io.undertow.servlet.api.LegacyThreadSetupActionWrapper$1.call(LegacyThreadSetupActionWrapper.java:44)
    at io.undertow.servlet.api.LegacyThreadSetupActionWrapper$1.call(LegacyThreadSetupActionWrapper.java:44)
    at io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:272)
    at io.undertow.servlet.handlers.ServletInitialHandler.access$000(ServletInitialHandler.java:81)
    at io.undertow.servlet.handlers.ServletInitialHandler$1.handleRequest(ServletInitialHandler.java:104)
    at io.undertow.server.Connectors.executeRootHandler(Connectors.java:202)
    at io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:805)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
Caused by: javax.el.PropertyNotWritableException: /forms/bestellungLieferant.xhtml @29,29 value="#{bestellungLieferantController.getAllAvailableKomponentDualListModel()}": Illegal Syntax for Set Operation
    at com.sun.faces.facelets.el.TagValueExpression.setValue(TagValueExpression.java:136)
    at javax.faces.component.UIInput.updateModel(UIInput.java:832)
    ... 53 more
Caused by: javax.el.PropertyNotWritableException: Illegal Syntax for Set Operation
    at com.sun.el.parser.AstValue.setValue(AstValue.java:228)
    at com.sun.el.ValueExpressionImpl.setValue(ValueExpressionImpl.java:294)
    at org.jboss.weld.el.WeldValueExpression.setValue(WeldValueExpression.java:64)
    at org.jboss.weld.el.WeldValueExpression.setValue(WeldValueExpression.java:64)
    at com.sun.faces.facelets.el.TagValueExpression.setValue(TagValueExpression.java:131)
    ... 54 more

My Converter:

@FacesConverter(value = "entityConverter")
public class EntityConverter implements Converter {

    private static Map<Object, String> entities = new WeakHashMap<Object, String>();

    @Override
    public String getAsString(FacesContext context, UIComponent component, Object entity) {
        synchronized (entities) {
            if (!entities.containsKey(entity)) {
                String uuid = UUID.randomUUID().toString();
                entities.put(entity, uuid);
                return uuid;
            } else {
                return entities.get(entity);
            }
        }
    }

    @Override
    public Object getAsObject(FacesContext context, UIComponent component, String uuid) {
        for (Entry<Object, String> entry : entities.entrySet()) {
            if (entry.getValue().equals(uuid)) {
                return entry.getKey();
            }
        }
        return null;
    }
}

Any hints are welcome.

Thanks in advance!

Why did you change your title this way? – Kukeltje Jan 27 '17 at 16:00 — Kukeltje, Jan 27 '17 at 16:00

JanPl · Answer 1 · 2017-01-27T19:33:39.927

3

You want to access a property in your backing bean. The property is not getAllAvailableKomponentDualListModel or allAvailableKomponentDualListModel but komponentenDualListModel

value="#{bestellungLieferantController.komponentDualListModel}"

You already have the setter and getter method in your bean. However, you need to call the method getAllAvailableKomponentDualListModel() before you access it from the view.

edited Jan 27 '17 at 19:33

answered Jan 27 '17 at 13:40

JanPl

794
6
19

True. But where to initialize the Model? I have a dynamic picklist which will be populated by database values. Therefor I need to call this method. – LupoZ Jan 27 '17 at 13:49
1

Add @PostConstruct to the method getAllAvailableKomponentDualListModel(). – JanPl Jan 27 '17 at 13:51
When I use "@PostConstruct" this method will be invoked once right? And if the user stood in this state for a while and the database values change he wouldn't work on actual data. How can I solve this? – LupoZ Jan 27 '17 at 13:53
Usually the user interacts with your web app by invoking an action. – JanPl Jan 27 '17 at 13:55
Maybe I wasn't precise. Do I need to implement a notify pattern? – LupoZ Jan 27 '17 at 13:57
Try the [primefaces poll component](http://www.primefaces.org/showcase/ui/ajax/poll.xhtml) – JanPl Jan 27 '17 at 14:02
Thank you very much. Now I get Error Rendering View[/forms/bestellungLieferant.xhtml]: java.lang.NullPointerException. I'll include my converter as source code above. – LupoZ Jan 27 '17 at 14:11
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/134194/discussion-between-lupoz-and-jan). – LupoZ Jan 27 '17 at 14:16

ArgaPK · Accepted Answer · 2017-01-27T15:58:30.843

2

Write like this in p:pickList component value attribute:

value="#{bestellungLieferantController.getAllAvailableKomponentDualListModel}"

Edit just to see try to return something else in this method like this:

@Override 
public Object getAsObject(FacesContext context, UIComponent component, String uuid) { 
for (Entry<Object, String> entry : entities.entrySet()) { 
if (entry.getValue().equals(uuid)) { 
return entry.getKey(); 
} 
} 
return uuid; 
}

edited Jan 27 '17 at 15:58

answered Jan 27 '17 at 13:21

ArgaPK

455
1
9
22

If you look above I just have a value definition. And your syntax is for accessing bean properties not methods. So the brackets are needed. – LupoZ Jan 27 '17 at 13:32
Removing parenthesis was correct but not sufficient. – JanPl Jan 27 '17 at 13:33
please do visit on primefaces homepage to see there is no brackets with methods. for e.g Upload method (file upload) http://www.primefaces.org/showcase/ui/file/upload/basic.xhtml – ArgaPK Jan 27 '17 at 13:36
@ArgaPK I'm sorry but I didn't know that. Thanks. – LupoZ Jan 27 '17 at 13:37
atleast first just try to remove brackets than tell us what happens. – ArgaPK Jan 27 '17 at 13:37
please don't say sorry, everybody have a right to say anything they want. i will be glad to hear if your problem is solved now. – ArgaPK Jan 27 '17 at 13:39
No the problem isn't solved just wanted to mention that your notation was right. But now I get this new error: /forms/bestellungLieferant.xhtml @31,30 value="#{bestellungLieferantController.getAllAvailableKomponentDualListModel}": The class 'BestellungLieferantController' does not have the property 'getAllAvailableKomponentDualListModel'. – LupoZ Jan 27 '17 at 13:43
visit this primefaces picklist demo, it tells that p:picklist value attribute should have the property and should not have any method ,so the proper property to call is "komponentenDualListModel;" – ArgaPK Jan 27 '17 at 13:48
@LupoZ call the method "getAllAvailableKomponentDualListModel()" by using p:ajax – ArgaPK Jan 27 '17 at 13:56
1

Seems wrong to me. Why is this an answer? – Tom Lensburry Jan 27 '17 at 19:37

Error Rendering View[dummy.xhtml]: java.lang.NullPointerException

2 Answers2