Question

Im trying to populate a JSF Datatable with data that I am retrieving from a DynamoDB Table (The Amazon NoSQL DB). At the moment everything is working fine right up to the Iteration over the scanResults. The debugger shows that my scanResult has a list of all the accounts but when I try to iterate over those results in order to construct my List nothing seems to be added to the allUserSummary List and I end up with a nullpointer exception.

The basic User POJO:

public class User {

private String uuid;

   public User(String uuid) {
       this.uuid = uuid;
   }
}

The managed bean:

private List<User> allUserSummary;
private List<String> uuid;
private User selectedUser;

public List<User> getAllUserSummary() throws Exception {
    populateData();
    return allUserSummary;
}

private void populateData() throws Exception {

    // Create a new AmazonDynamoDBClient and mapper
    AmazonDynamoDBClient client = dynamoClient.getDynamoClient();
    DynamoDBMapper mapper = new DynamoDBMapper(client);


    try {
        // Create a new scan expression and filter to find the required data from the db
        DynamoDBScanExpression scanExpression = new DynamoDBScanExpression();
        Map<String, Condition> scanFilter = new HashMap<String, Condition>();
        Condition scanCondition = new Condition().withComparisonOperator(ComparisonOperator.NOT_NULL);
        scanFilter.put("uuid", scanCondition);
        scanExpression.setScanFilter(scanFilter);

        // Run the scan
        List scanResults = mapper.scan(UserAccounts.class, scanExpression);

        // Iterate over the scanned results and add the required data to a new User
        for (Iterator it = scanResults.iterator(); it.hasNext();) {
            allUserSummary.add(new User(scanResults.get(1).toString()));
        }

    } catch (Exception e) {
        // TODO
    }

}

The Datatable (Im using primefaces but the problem is the same with standard JSF DT):

            <h:form>



                <pou:dataTable id="users" 
                               var="user" 
                               value="#{accountManager.allUserSummary}" 
                               paginator="true" 
                               rows="10"
                               selection="#{accountManager.selectedUser}">  

                    <f:facet name="header">  
                        UUID  
                    </f:facet>  

                    <pou:column selectionMode="multiple" />  

                    <pou:column headerText="Uuid">  
                        #{user.uuid}  
                    </pou:column>  

                    <f:facet name="footer">  
                        <pou:commandButton id="multiViewButton" 
                                           value="View" 
                                           icon="ui-icon-search"
                                           update="" 
                                           oncomplete=""/>  
                    </f:facet>  
                </pou:dataTable>  

            </h:form>

STACK TRACE:

java.lang.IllegalArgumentException: ""
    at javax.faces.component.UIComponentBase.findComponent(UIComponentBase.java:570)
    at org.primefaces.util.ComponentUtils.findClientIds(ComponentUtils.java:244)
    at org.primefaces.renderkit.CoreRenderer.buildAjaxRequest(CoreRenderer.java:222)
    at org.primefaces.component.commandbutton.CommandButtonRenderer.encodeMarkup(CommandButtonRenderer.java:81)
    at org.primefaces.component.commandbutton.CommandButtonRenderer.encodeEnd(CommandButtonRenderer.java:53)
    at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:875)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1764)
    at org.primefaces.component.datatable.DataTableRenderer.encodeFacet(DataTableRenderer.java:839)
    at org.primefaces.component.datatable.DataTableRenderer.encodeTFoot(DataTableRenderer.java:823)
    at org.primefaces.component.datatable.DataTableRenderer.encodeRegularTable(DataTableRenderer.java:247)
    at org.primefaces.component.datatable.DataTableRenderer.encodeMarkup(DataTableRenderer.java:224)
    at org.primefaces.component.datatable.DataTableRenderer.encodeEnd(DataTableRenderer.java:108)
    at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:875)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1764)
    at javax.faces.render.Renderer.encodeChildren(Renderer.java:168)
    at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:845)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1757)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1760)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1760)
    at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:402)
    at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:131)
    at javax.faces.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:288)
    at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:121)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
    at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:594)
    at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1542)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:343)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:217)
    at org.apache.shiro.web.servlet.ProxiedFilterChain.doFilter(ProxiedFilterChain.java:61)
    at org.apache.shiro.web.servlet.AdviceFilter.executeChain(AdviceFilter.java:108)
    at org.apache.shiro.web.servlet.AdviceFilter.doFilterInternal(AdviceFilter.java:137)
    at org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:125)
    at org.apache.shiro.web.servlet.ProxiedFilterChain.doFilter(ProxiedFilterChain.java:66)
    at org.apache.shiro.web.servlet.AdviceFilter.executeChain(AdviceFilter.java:108)
    at org.apache.shiro.web.servlet.AdviceFilter.doFilterInternal(AdviceFilter.java:137)
    at org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:125)
    at org.apache.shiro.web.servlet.ProxiedFilterChain.doFilter(ProxiedFilterChain.java:66)
    at org.apache.shiro.web.servlet.AbstractShiroFilter.executeChain(AbstractShiroFilter.java:449)
    at org.apache.shiro.web.servlet.AbstractShiroFilter$1.call(AbstractShiroFilter.java:365)
    at org.apache.shiro.subject.support.SubjectCallable.doCall(SubjectCallable.java:90)
    at org.apache.shiro.subject.support.SubjectCallable.call(SubjectCallable.java:83)
    at org.apache.shiro.subject.support.DelegatingSubject.execute(DelegatingSubject.java:380)
    at org.apache.shiro.web.servlet.AbstractShiroFilter.doFilterInternal(AbstractShiroFilter.java:362)
    at org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:125)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:217)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:279)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
    at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
    at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:161)
    at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:331)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231)
    at com.sun.enterprise.v3.services.impl.ContainerMapper$AdapterCallable.call(ContainerMapper.java:317)
    at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:195)
    at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:849)
    at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:746)
    at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1045)
    at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:228)
    at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
    at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
    at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
    at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
    at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
    at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
    at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
    at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
    at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
    at java.lang.Thread.run(Thread.java:680)

Answer 1

here you go…

Set values into update="" and oncomplete="" or remove them from your button…

                    <pou:commandButton id="multiViewButton" 
                                       value="View" 
                                       icon="ui-icon-search"
                                       update="" 
                                       oncomplete=""/>  

EDIT

try the following changes :

private List<User> allUserSummary = new ArrayList<User>();

.
.
.

@PostConstruct
public void populateData() throws Exception {

.
.
.
.

public List<User> getAllUserSummary() throws Exception {
    return allUserSummary;
}