flex 4.5中的自定義着色錯誤Mobile

Question

我試圖在數值爲< 0時使數據紅色，否則爲綠色。我用來顯示列和我的itemRenderer動作腳本文件給我錯誤「無法訪問屬性的一個null對象，在我作爲文件，當我調試時，我可以看到」數據「變量的值爲null，並儘快它調用超級構造它給這個錯誤

我的動作腳本文件

public class ConditionalColoredLabelAS extends LabelItemRenderer 
{ 
    public function ConditionalColoredLabelAS() { 
     if (data !=null) 
     super(); 

    } 

    // Use the value of the myColor property to draw 
    // the background color of the item in the list. 
    override protected function drawBackground(unscaledWidth:Number, unscaledHeight:Number):void { 
     // Define a var to hold the color. 
     var myColor:uint; 
     if (data !=null) 
     { 
      // Determine the RGB color value from the label property. 
     if (data == "red") 
      myColor = 0xFF0000; 
     if (data == "green") 
      myColor = 0x00FF00; 
     if (data == "blue") 
      myColor = 0x0000FF; 
     } 
     //graphics.beginFill(myColor, 1); 
     //graphics.drawRect(0, 0, unscaledWidth, unscaledHeight); 

    } 
} 

我從MXML文件調用：

   <s:GridColumn id="name1" dataField="name" headerText="Name" /> 
       <s:GridColumn dataField="excess_return" headerText="Excess Return" itemRenderer="util.ConditionalColoredLabelAS"/> 

錯誤是

TypeError: Error #1009: Cannot access a property or method of a null object reference. 
    at spark.components::Group/addElement()[E:\dev\4.5.1\frameworks\projects\spark\src\spark\components\Group.as:1342] 
    at spark.components.gridClasses::GridLayout/createTypicalItemRenderer()[E:\dev\4.5.1\frameworks\projects\spark\src\spark\components\gridClasses\GridLayout.as:748] 
    at spark.components.gridClasses::GridLayout/updateTypicalCellSizes()[E:\dev\4.5.1\frameworks\projects\spark\src\spark\components\gridClasses\GridLayout.as:883] 
    at spark.components.gridClasses::GridLayout/measure()[E:\dev\4.5.1\frameworks\projects\spark\src\spark\components\gridClasses\GridLayout.as:444] 
    at spark.components.supportClasses::GroupBase/measure()[E:\dev\4.5.1\frameworks\projects\spark\src\spark\components\supportClasses\GroupBase.as:1148] 
    at mx.core::UIComponent/measureSizes()[E:\dev\4.5.1\frameworks\projects\framework\src\mx\core\UIComponent.as:8496] 
    at mx.core::UIComponent/validateSize()[E:\dev\4.5.1\frameworks\projects\framework\src\mx\core\UIComponent.as:8420] 
    at spark.components::Group/validateSize()[E:\dev\4.5.1\frameworks\projects\spark\src\spark\components\Group.as:1012] 
    at mx.managers::LayoutManager/validateClient()[E:\dev\4.5.1\frameworks\projects\framework\src\mx\managers\LayoutManager.as:987] 
    at mx.core::UIComponent/validateNow()[E:\dev\4.5.1\frameworks\projects\framework\src\mx\core\UIComponent.as:8067] 
    at spark.components::ViewNavigator/commitNavigatorAction()[E:\dev\4.5.1\frameworks\projects\mobilecomponents\src\spark\components\ViewNavigator.as:1878] 
    at spark.components::ViewNavigator/commitProperties()[E:\dev\4.5.1\frameworks\projects\mobilecomponents\src\spark\components\ViewNavigator.as:1236] 
    at mx.core::UIComponent/validateProperties()[E:\dev\4.5.1\frameworks\projects\framework\src\mx\core\UIComponent.as:8209] 
    at mx.managers::LayoutManager/validateProperties()[E:\dev\4.5.1\frameworks\projects\framework\src\mx\managers\LayoutManager.as:597] 
    at mx.managers::LayoutManager/doPhasedInstantiation()[E:\dev\4.5.1\frameworks\projects\framework\src\mx\managers\LayoutManager.as:783] 
    at mx.managers::LayoutManager/doPhasedInstantiationCallback()[E:\dev\4.5.1\frameworks\projects\framework\src\mx\managers\LayoutManager.as:1180] 

Answer 1

終於找到了答案

的 功能

private function returnItemRenderer(item: Object, column: GridColumn): IFactory  

     { 
      if (item == null) 
       return default_grid_item_renderer; 

      //var field:String = column.dataField; 
      if(item._return < 0) 
       return red_grid_item_renderer; 
      else if (item._return>0) 
       return green_grid_item_renderer; 
      return default_grid_item_renderer; 
      //return new ClassFactory(DefaultGridItemRenderer);   
     } 
    ]]> 
</fx:Script> 

的聲明是

<fx:Declarations> 
    <fx:Component id="default_grid_item_renderer" > 
     <s:DefaultGridItemRenderer /> 
    </fx:Component> 
    <fx:Component id="red_grid_item_renderer" > 
     <s:DefaultGridItemRenderer color="0xFF0000"/> 
    </fx:Component> 
    <fx:Component id="green_grid_item_renderer" > 
     <s:DefaultGridItemRenderer color="0x00FF00"/> 
    </fx:Component> 
</fx:Declarations> 

<s:DataGrid id="top5Grid" width="100%" height="100%" 
        dataProvider="{getDataResultMax.lastResult}"> 
      <s:columns> 
       <s:ArrayList> 

        <s:GridColumn dataField="impact" headerText="Impact" itemRendererFunction="impactItemRenderer"/> 
        <s:GridColumn dataField="_return" headerText="Return" itemRendererFunction="returnItemRenderer"/> 
       </s:ArrayList>  
      </s:columns> 
     </s:DataGrid>