flex 4.5 Mobile中的自定义着色错误

flex 4.5 Mobile中的自定义着色错误,mobile,itemrenderer,flex4.5,Mobile,Itemrenderer,Flex4.5,当值 声明如下: <s:GridColumn id="name1" dataField="name" headerText="Name" /> <s:GridColumn dataField="excess_return" headerText="Excess Return" itemRenderer="util.ConditionalColoredLabelAS"/> <fx:Declaratio

当值<0时,我尝试将数据涂成红色,否则为绿色。我正在使用显示列,并且我的itemRenderer操作脚本文件给了我错误“无法访问
null
对象的属性”。在我的as文件中,当我调试时,我可以看到“data”变量的值为
null
,一旦它调用超级构造函数,它就会给出此错误

                <s:GridColumn id="name1" dataField="name" headerText="Name" />
                <s:GridColumn dataField="excess_return" headerText="Excess Return" itemRenderer="util.ConditionalColoredLabelAS"/>
我的动作脚本文件

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); 

    }
}
                <s:GridColumn id="name1" dataField="name" headerText="Name" />
                <s:GridColumn dataField="excess_return" headerText="Excess Return" itemRenderer="util.ConditionalColoredLabelAS"/>
我从mxml文件中的调用是:

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

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

终于找到了答案

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

                <s:GridColumn id="name1" dataField="name" headerText="Name" />
                <s:GridColumn dataField="excess_return" headerText="Excess Return" itemRenderer="util.ConditionalColoredLabelAS"/>
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>
private函数returnItemRenderer(项:对象,列:GridColumn):IFactory
{   
如果(项==null)
返回默认的网格项目渲染器;
//变量字段:String=column.dataField;
如果(项目返回<0)
返回红色网格项目渲染器;
否则如果(项目返回>0)
返回绿色网格项目渲染器;
返回默认的网格项目渲染器;
//返回新的类工厂(DefaultGridItemRenderer);
}   
]]>
声明如下:

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

它不允许我放置声明,所以它们就在这里