TypeError：错误＃1009：无法访问空对象引用的属性或方法

Question

启动应用程序时，出现此错误（关闭所有类型的Flash类型，然后继续），但我没有主意：

TypeError：错误＃1009：无法访问空对象引用的属性或方法。 在Magazin / xmlService_resultHandler（）[D：\\ Documents and Settings \\ chechu \\ Adob​​e Flash Builder 4 \\ Magazin \\ src \\ Magazin.mxml：41]在Magazin / __ xmlService_result（）[D：\\ Documents and Settings \\ chechu \\ Adob​​e Flash Builder 4 \\ Magazin \\ src \\ Magazin.mxml：64]在flash.events::EventDispatcher/dispatchEventFunction（）在flash.events::EventDispatcher/dispatchEvent（）在HTTPOperation / http://www.adobe.com/2006/flex / mx / internal :: dispatchRpcEvent（）[E ：\\ dev \\ 4.x \\ frameworks \\ projects \\ rpc \\ src \\ mx \\ rpc \\ http \\ HTTPService.as：989，位于mx.rpc :: AbstractInvoker / http：/ /www.adobe.com/2006/flex/mx/internal::resultHandler()[e ：\\ dev \\ 4.x \\ frameworks \\ projects \\ rpc \\ src \\ mx \\ rpc \\ AbstractInvoker.as：318]在mx。 rpc :: Responder / result（）[E：\\ dev \\ 4.x \\ frameworks \\ projects \\ rpc \\ src \\ mx \\ rpc \\ Responder.as：56] at mx.rpc :: AsyncRequest / acknowledge（）[E： DirectHTTPMessageResponder / completeHandler（）处的\\ dev \\ 4.x \\ frameworks \\ projects \\ rpc \\ src \\ mx \\ rpc \\ AsyncRequest.as：84] [E：\\ dev \\ 4.x \\ frameworks \\ projects \\ rpc \\ src \\ mx \\ messaging \\ channels \\ DirectHTTPChannel.as：446]，位于flash.ev ents :: EventDispatcher / dispatchEventFunction（）在flash.events::EventDispatcher/dispatchEvent（）在flash.net::URLLoader/onComplete（）

主要应用：

  import events.ProductEvent;

  import mx.collections.ArrayCollection;
  import mx.controls.Alert;
  import mx.events.FlexEvent;
  import mx.rpc.events.FaultEvent;
  import mx.rpc.events.ResultEvent;

  import valueObject.ImageClass;
  [Bindable]
  public  var  imagesCollection:ArrayCollection;
  protected function xmlService_faultHandler(event:FaultEvent):void
  {
    Alert.show("meeah");

  }


  protected  function xmlService_resultHandler(event:ResultEvent):void
  {
    var imageCollection:ArrayCollection=event.result.Images.image ;
    var imData:ImageClass;
    for each(var im:Object in imageCollection)
    {
      imData=new ImageClass();
      imData.url=im.url;
      imData.big_url=im.big_url;
      imData.cat=im.cat;
      imData.descript=im.descript;
      imData.price=im.price;
      imagesCollection.addItem(imData); line:41

    }
    Alert.show("gg");
  }
  [Bindable]
  public var mama:ArrayCollection=new ArrayCollection();



  protected function gallery1_addToCartHandler(event:ProductEvent):void
  {
     mama.addItem(event);
    currentState="cart"; 
      }

    ]]>
</fx:Script>
  <s:states>
    <s:State name="normal"/>
    <s:State name="cart"/>
  </s:states>
  <fx:Declarations>    
    <s:HTTPService id="xmlService"  line 64
                   url="dataXml/pics.xml" fault="xmlService_faultHandler(event)" 
                   result="xmlService_resultHandler(event)"/>

  </fx:Declarations>

  <components:Gallery imagesArray="{imagesCollection}" addToCart="gallery1_addToCartHandler(event)"   />

  <components:cart  x="500" y="300" itemRenderer="components.CartRenderer" dataProvider="{mama}"  />
</s:Application>

图库组件：

<?xml version="1.0" encoding="utf-8"?>
<s:Group xmlns:fx="http://ns.adobe.com/mxml/2009" 
         xmlns:s="library://ns.adobe.com/flex/spark" 
         xmlns:mx="library://ns.adobe.com/flex/mx"   >
  <fx:Declarations>
    <!-- Place non-visual elements (e.g., services, value objects) here -->
  </fx:Declarations>

  <fx:Metadata>
    [Event(name="addToCart",type="events.ProductEvent")]
  </fx:Metadata>

  <s:layout>
    <s:VerticalLayout/>
  </s:layout>

  <fx:Script>
    <![CDATA[
      import events.ProductEvent;

      import mx.collections.ArrayCollection;

      import valueObject.ImageClass;
      [Bindable]
      public var imagesArray:ArrayCollection;



      public function goa_clickHandler(event:MouseEvent):void
      {
        for (var i:uint=0; i<imagesArray.length;i++)
        {
          var objEvent:ProductEvent=new ProductEvent("addToCart",true);
          objEvent.imData=imagesArray[i] ;
          dispatchEvent(objEvent);
        }
      }
    ]]>
  </fx:Script>
  <s:SkinnableDataContainer id="cont"  dataProvider="{imagesArray}">

    <s:itemRenderer >

      <fx:Component>

        <s:ItemRenderer>

          <s:HGroup>
            <s:Label id="gagal" text="{data.price}"/>
            <mx:Image source="{data.url}" width="50" height="50" />
            <s:Button id="goa"  label="buy" click="outerDocument.goa_clickHandler(event)"/>
          </s:HGroup>

        </s:ItemRenderer>

      </fx:Component>



    </s:itemRenderer>

  </s:SkinnableDataContainer>


</s:Group>

ProductEvent类：

package events
{
  import flash.events.Event;

  import valueObject.ImageClass;

  [Bindable]
  public class ProductEvent extends Event
  {

    public var imData:ImageClass;


    public function ProductEvent(type:String,bubbles:Boolean=true)
    {
      super(type,bubbles);


    }
    override public function clone():Event
    {
      var eventOb:ProductEvent=new ProductEvent(type,bubbles);
      eventOb.imData=this.imData;
      return eventOb;

    }
  }

ImageClass：

package valueObject
 {
  [Bindable]
  public class ImageClass
  {
    public var url:String;
    public var big_url:String;
    public var descript:String;
    public var price:String;
    public var cat:String;

    public function ImageClass()
    {
      /*this.url=url;
      this.big_url=big_url;
      this.descript=descript;
      this.price=price;
      this.cat=cat;*/
    }
  }
}

和xml：

<?xml version="1.0"?>
<Images>
 <image> 
  <url>poze/pics/IMG_1163.jpg</url>
  <big_url>poze/big_pics/IMG_1163.jpg </big_url>
  <descript>P</descript>
  <price>99.99</price>
  <cat>A</cat>
 </image>
 <image>
  <url>poze/pics/IMG_1175.jpg</url>
  <big_url>poze/big_pics/IMG_1175.jpg</big_url>
  <descript>U</descript>
  <price>99.99</price>
  <cat>A</cat>
 </image>
 <image>
  <url>poze/pics/IMG_1186.jpg</url>
  <big_url>poze/big_pics/IMG_1186.jpg</big_url>
  <descript>L</descript>
  <price>99.99</price>
  <cat>A</cat>
 </image>

Answer 1

您正在第41行中访问imagesCollection变量，但尚未对其进行初始化-它仍包含null

要么改变

[Bindable]
public  var  imagesCollection:ArrayCollection;

至

[Bindable]
public  var  imagesCollection:ArrayCollection = new ArrayCollection();

或添加

imagesCollection  = new ArrayCollection();

到xmlService_resultHandler方法的开头。

Answer 2

记得...

只要存在空引用错误，就需要初始化所使用的变量。

说如果您使用Array或ArrayCollection

• 您需要做： yourArrayVarriable = new Array(); 在函数内部或
• 您需要执行以下操作： yourArrayCollectionVarriable = new ArrayCollection(); 在函数内部

然后开始使用yourArrayVarriable或yourArrayCollectionVarriable存储值