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我在向primefaces数据表中添加行的方法的实现有什么问题？

[英]What is wrong with my implementation of a method to add row to a primefaces datatable?

 原文  2013-04-21 04:12:48  7   2    java-ee/ jsf-2/ primefaces

问题描述

我正在使用JavaServer Faces 2.0和Primefaces 3.5，并在Glassfish 3.1.2上运行它。 我在页面上有一个数据表，该数据表用于允许用户创建琐事问题，设置其属性并为其添加可能的答案，然后将其作为实体对象存储在表中。 所以我使用数据表的Primefaces实现创建了一个数据表 

<p:dataTable 
    id="answersTable" var="answer" style="width: 250px"
    value="#{createQuestionBean.datamodel}"   
    selection="#{createQuestionBean.selectedAnswer}"
    editMode="cell" editable="true"
    selectionMode="single">

    <p:column style="width:75%"> 
        <p:cellEditor >  
            <f:facet name="output">
                <h:outputText 
                    value="#{answer.answer.testAnswer}" />
            </f:facet>  
            <f:facet name="input">
                <p:inputText 
                    id="modelInput"  
                    style="width: 97%;height: 97%"
                    value="#{answer.answer.testAnswer}"/>
            </f:facet>  
        </p:cellEditor>  
    </p:column>
    <p:column style="width:25%">  
        #{answer.correct ? "Correct" : "Wrong" }  
    </p:column>

</p:dataTable>

我在表格后添加了一个按钮，以允许用户添加答案（因此他们可能会有两个以上的答案） 

<p:commandButton 
    update="answersTable"
    value="Add +" partialSubmit="true"
    actionListener="#{createQuestionBean.addQuestion}"/>

这是按钮调用的方法 

public void addQuestion() {
    answers.add(new QuestionAnswers());
    answers.get(answers.size() - 1).setCorrect(false);
    setIDs();
    //set the data models
    datamodel = new QuestionAnswersDataModel(answers);
}

当我运行init方法时，我会两次调用addQuestion（）方法，并且在页面加载时，我会看到两个答案，它们的行为与应有的行为完全相同。 但是，当我单击按钮时，除了此Stacktrace，我什么也没有： 

SEVERE: Unable to create new Collection instance for type java.util.Arrays$ArrayList
java.lang.InstantiationException: java.util.Arrays$ArrayList
    at java.lang.Class.newInstance0(Class.java:357)
    at java.lang.Class.newInstance(Class.java:325)
    at com.sun.faces.renderkit.html_basic.MenuRenderer.createCollection(MenuRenderer.java:907)
    at com.sun.faces.renderkit.html_basic.MenuRenderer.convertSelectManyValuesForModel(MenuRenderer.java:367)
    at com.sun.faces.renderkit.html_basic.MenuRenderer.convertSelectManyValue(MenuRenderer.java:129)
    at com.sun.faces.renderkit.html_basic.MenuRenderer.getConvertedValue(MenuRenderer.java:315)
    at org.primefaces.component.selectmanycheckbox.SelectManyCheckboxRenderer.getConvertedValue(SelectManyCheckboxRenderer.java:37)
    at javax.faces.component.UIInput.getConvertedValue(UIInput.java:1030)
    at javax.faces.component.UIInput.validate(UIInput.java:960)
    at javax.faces.component.UIInput.executeValidate(UIInput.java:1233)
    at javax.faces.component.UIInput.processValidators(UIInput.java:698)
    at javax.faces.component.UIForm.processValidators(UIForm.java:253)
    at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1214)
    at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1214)
    at javax.faces.component.UIViewRoot.processValidators(UIViewRoot.java:1172)
    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:118)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:593)
    at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1550)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:343)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:217)
    at org.primefaces.webapp.filter.FileUploadFilter.doFilter(FileUploadFilter.java:79)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:217)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:118)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:103)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:54)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilter(BasicAuthenticationFilter.java:150)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:183)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:105)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.access.channel.ChannelProcessingFilter.doFilter(ChannelProcessingFilter.java:144)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:192)
    at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160)
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346)
    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:259)
    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$AdapterCallable.call(ContainerMapper.java:317)
    at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:195)
    at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:860)
    at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:757)
    at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1056)
    at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:229)
    at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
    at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
    at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
    at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
    at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
    at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
    at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
    at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
    at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
    at java.lang.Thread.run(Thread.java:722)

我找不到我的问题在哪里。 我知道我在init方法中实例化了该列表，即使没有，它也不会加载该页面。 只有在第一次按下按钮时才会发生例外。

2 个解决方案

解决方案1
 0  2013-04-21 04:59:19

尝试更改datamodel = new QuestionAnswersDataModel(answers);

至

datamodel = new QuestionAnswersDataModel(new ArrayList<QuestionAnswers>(answers));

那应该解决问题。

解决方案2
 0 已采纳  2013-04-22 05:19:18

试试datamodel.setWrappedData(answers); 代替

至于为什么发生； 尽管我无法提供详细信息（并且似乎无法获得DataModel的实现源），但似乎DataModel有时试图创建java.util.Arrays$ArrayList的实例。 我们在这里讨论的ArraysList不是来自java.util那个，而是Arrays类的一个内部类 。

另外，您可能会对知道实际上不需要 DataModel类感兴趣。 您可以按原样使用ArrayList 。 这样，您每次修改数据模型时都不需要重新包装全新的阵列。 只需添加到java.util.ArrayList并重新渲染您的数据表

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