两个 selectManyListbox 出错

发布于 2024-11-24 19:22:51 字数 4068 浏览 2 评论 0原文

我有两个相关的 selectManyListbox(第二个是根据第一个生成的),但是当 我运行应用程序时发生错误:

JSF:

<h:selectManyListbox   value="#{TestAjax.selectedProjects}"  id="project" size="3">
  <f:selectItem itemLabel="-- Select Projects -- " itemValue="0"/> 
  <f:selectItems value="#{TestAjax.getMyListProject()}" />
  <f:ajax event="change"  render="status" />
 </h:selectManyListbox>

 <h:selectManyListbox   value="#{TestAjax.selectedstatus}" id="status"  size="3">
  <f:selectItem itemLabel="-- Select status -- " itemValue="0"/> 
  <f:selectItems value="#{TestAjax.StepsByProject()}" />
 </h:selectManyListbox>

错误:

java.lang.NullPointerException
at DAOKPI.TestAjax.FormattingVar(TestAjax.java:342)
at DAOKPI.TestAjax.StepsByProject(TestAjax.java:367)
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 javax.el.BeanELResolver.invokeMethod(BeanELResolver.java:737)
at javax.el.BeanELResolver.invoke(BeanELResolver.java:467)
at javax.el.CompositeELResolver.invoke(CompositeELResolver.java:254)
at com.sun.el.parser.AstValue.getValue(AstValue.java:111)
at com.sun.el.parser.AstValue.getValue(AstValue.java:163)
at com.sun.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:219)
at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:109)
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:194)
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:182)
at javax.faces.component.UISelectItems.getValue(UISelectItems.java:129)
at com.sun.faces.renderkit.SelectItemsIterator.initializeItems(SelectItemsIterator.java:202)
at com.sun.faces.renderkit.SelectItemsIterator.hasNext(SelectItemsIterator.java:135)
at com.sun.faces.renderkit.html_basic.MenuRenderer.renderOptions(MenuRenderer.java:762)
at com.sun.faces.renderkit.html_basic.MenuRenderer.renderSelect(MenuRenderer.java:844)
at com.sun.faces.renderkit.html_basic.MenuRenderer.encodeEnd(MenuRenderer.java:298)
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:875)
at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeRecursive(HtmlBasicRenderer.java    :312)
at com.sun.faces.renderkit.html_basic.GridRenderer.renderRow(GridRenderer.java:185)
at com.sun.faces.renderkit.html_basic.GridRenderer.encodeChildren(GridRenderer.java:129)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:845)
at org.primefaces.renderkit.CoreRenderer.renderChild(CoreRenderer.java:55)
at org.primefaces.renderkit.CoreRenderer.renderChildren(CoreRenderer.java:43)
at org.primefaces.component.panel.PanelRenderer.encodeContent(PanelRenderer.java:229)
at org.primefaces.component.panel.PanelRenderer.encodeMarkup(PanelRenderer.java:152)
at org.primefaces.component.panel.PanelRenderer.encodeEnd(PanelRenderer.java:75)
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:875)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1763)
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:1756)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1759)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1759)
at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingSt     rategy.java:401)
at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:131)
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)

I have two selectManyListbox related(the second is generated accordind the first) ,but when
I run the application an error occure:

JSF:

<h:selectManyListbox   value="#{TestAjax.selectedProjects}"  id="project" size="3">
  <f:selectItem itemLabel="-- Select Projects -- " itemValue="0"/> 
  <f:selectItems value="#{TestAjax.getMyListProject()}" />
  <f:ajax event="change"  render="status" />
 </h:selectManyListbox>

 <h:selectManyListbox   value="#{TestAjax.selectedstatus}" id="status"  size="3">
  <f:selectItem itemLabel="-- Select status -- " itemValue="0"/> 
  <f:selectItems value="#{TestAjax.StepsByProject()}" />
 </h:selectManyListbox>

The error:

java.lang.NullPointerException
at DAOKPI.TestAjax.FormattingVar(TestAjax.java:342)
at DAOKPI.TestAjax.StepsByProject(TestAjax.java:367)
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 javax.el.BeanELResolver.invokeMethod(BeanELResolver.java:737)
at javax.el.BeanELResolver.invoke(BeanELResolver.java:467)
at javax.el.CompositeELResolver.invoke(CompositeELResolver.java:254)
at com.sun.el.parser.AstValue.getValue(AstValue.java:111)
at com.sun.el.parser.AstValue.getValue(AstValue.java:163)
at com.sun.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:219)
at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:109)
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:194)
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:182)
at javax.faces.component.UISelectItems.getValue(UISelectItems.java:129)
at com.sun.faces.renderkit.SelectItemsIterator.initializeItems(SelectItemsIterator.java:202)
at com.sun.faces.renderkit.SelectItemsIterator.hasNext(SelectItemsIterator.java:135)
at com.sun.faces.renderkit.html_basic.MenuRenderer.renderOptions(MenuRenderer.java:762)
at com.sun.faces.renderkit.html_basic.MenuRenderer.renderSelect(MenuRenderer.java:844)
at com.sun.faces.renderkit.html_basic.MenuRenderer.encodeEnd(MenuRenderer.java:298)
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:875)
at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeRecursive(HtmlBasicRenderer.java    :312)
at com.sun.faces.renderkit.html_basic.GridRenderer.renderRow(GridRenderer.java:185)
at com.sun.faces.renderkit.html_basic.GridRenderer.encodeChildren(GridRenderer.java:129)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:845)
at org.primefaces.renderkit.CoreRenderer.renderChild(CoreRenderer.java:55)
at org.primefaces.renderkit.CoreRenderer.renderChildren(CoreRenderer.java:43)
at org.primefaces.component.panel.PanelRenderer.encodeContent(PanelRenderer.java:229)
at org.primefaces.component.panel.PanelRenderer.encodeMarkup(PanelRenderer.java:152)
at org.primefaces.component.panel.PanelRenderer.encodeEnd(PanelRenderer.java:75)
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:875)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1763)
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:1756)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1759)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1759)
at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingSt     rategy.java:401)
at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:131)
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)

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我ぃ本無心為│何有愛 2024-12-01 19:22:52
java.lang.NullPointerException
at DAOKPI.TestAjax.FormattingVar(TestAjax.java:342)
at DAOKPI.TestAjax.StepsByProject(TestAjax.java:367)

这告诉你所有你需要知道的事情。您的类 TestAjax 中发生空指针异常,方法为 FormattingVar(),行号为 342。
从您的 JSF 页面中,错误发生在第二个 selectManyListbox 中,如堆栈跟踪中的 StepsByProject() 所示

java.lang.NullPointerException
at DAOKPI.TestAjax.FormattingVar(TestAjax.java:342)
at DAOKPI.TestAjax.StepsByProject(TestAjax.java:367)

This tells you all you need to know. A null pointer exception occured in your class TestAjax, the method was FormattingVar() and the line number is 342.
From your JSF page, the error occured in the 2nd selectManyListbox, as seen by the StepsByProject() in the stacktrace as well

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