通过p：ajax监听器获取NullPointerException

Question

我有app.xhtml，有一个数据表和面板。我正在使用Apache Tomcat服务器。我部署了该项目，这个数据表选择监听器没有问题。但是该项目已经部署了一周，之后我在数据表行选择监听器中得到NullPointerException。当我重新启动Tomcat时，问题就解决了。每隔7天，8天发生此问题，并重新启动Tomcat解决此问题。 数据表是惰性的，有Person和Applications类。每个人都有很多申请。

下面是app.xhtml的一部分

<p:dataTable id="appDataTable"
             var="applications"
             value="#{appView.applicationLazy}"
             rowKey="#{applications.id}"
             paginator="true" rows="20"
             emptyMessage="#{"No Record"}"
             currentPageReportTemplate=" #{"Page"} ({currentPage}/{totalPages})"

             paginatorTemplate="{CurrentPageReport}
             {FirstPageLink} {PreviousPageLink}
             {PageLinks} {NextPageLink} {LastPageLink}
             {RowsPerPageDropdown}"

             rowsPerPageTemplate="20,50,100"
             lazy="true"
             selection="#{appView.selectedApplication}" selectionMode="single">

    <p:ajax event="rowSelect"
            onstart="ustPanel.collapse();"
            update="detailPanel"
            listener="#{appView.datatableRowSelectListener()}"/>
    <p:ajax event="rowUnselect" update="detailPanel"/>


    <f:facet name="header">
        #{"Applications"}
    </f:facet>
    <p:column headerText="#{"name"}"
              sortBy="#{appView.person.name}"
              filterBy="#{appView.person.name}" >
        <h:outputText value="#{appView.person.name}" >
        </h:outputText>
    </p:column>
    <p:column headerText="#{"surname"}"
              sortBy="#{appView.person.surname}"
              filterBy="#{appView.person.surname}" >
        <h:outputText value="#{appView.person.surname}" />
    </p:column>

    <p:column headerText="#{"mobilePhone"}"
              sortBy="#{appView.person.mobilePhone}"
              filterBy="#{appView.person.mobilePhone}"
              >
        <h:outputText value="#{appView.person.mobilePhone}" />
    </p:column>

    <p:column headerText="#{"date"}"
              sortBy="#{appView.date}"
              filterBy="#{appView.date}" >
        <h:outputText value="#{appView.showDate(applications.date)}" />

    </p:column>

    <f:facet name="footer">
        #{"total records"}: #{appView.applicationLazy.rowCount}
    </f:facet>
</p:dataTable>

此处也是AppView bean类的一部分;

@ManagedBean
@ViewScoped
public class AppView extends BaseView implements Serializable {

    private Applications selectedApplication;
    private String name;
    private String surname;
    private String mobile;
    private String date;

    @PostConstruct
    public void init() {

        applicationLazy = new LazyDataModel<Basvurular>() {
            @Override
            public List<Applications> load(int first, int pageSize, String sortField, SortOrder sortOrder, Map<String, String> filters) {
                applicationLazy.setRowCount(commonService.applicationsProjection(filters));
                return commonService.applicationsLazyLoad(first, pageSize, sortField, sortOrder, filters);
            }
        };
    }

    public void datatableRowSelectListener() {

        try {
            Locale loc = new Locale("tr", "TR");

            date = selectedApplication.getDate();
            name = selectedApplication.getPerson().getName().toUpperCase(loc);
            surname = selectedApplication.getPerson().getSurname().toUpperCase(loc);
            mobile = selectedApplication.getPerson().getMobilePhone();

        } catch (Exception ex) {
            ex.printStackTrace();

        }
    }
}

这是Tomcat的例外：

java.lang.NullPointerException
javax.el.ELException: /app.xhtml @55,173 listener="#{appView.datatableRowSelectListener()}": java.lang.NullPointerException


at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:111)
    at 

org.primefaces.component.behavior.ajax.AjaxBehaviorListenerImpl.processAjaxBehavior(AjaxBehaviorListenerImpl.java:53)
    at 

org.primefaces.event.SelectEvent.processListener(SelectEvent.java:40)
    at javax.faces.component.behavior.BehaviorBase.broadcast(BehaviorBase.java:102)
    at 

javax.faces.component.UIComponentBase.broadcast(UIComponentBase.java:769)
    at javax.faces.component.UIData.broadcast(UIData.java:893)
    at 

javax.faces.component.UIData.broadcast(UIData.java:915)
    at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:787)
    at 

javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1252)
    at com.sun.faces.lifecycle.InvokeApplicationPhase.execute

(InvokeApplicationPhase.java:81)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
    at com.sun.faces.lifecycle.LifecycleImpl.execute

(LifecycleImpl.java:118)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:508)
    at