オーバーライド保護された関数createChildrenが無視されるのはなぜですか？ここ

Question

は誤りである：ここでは

 
    TypeError: Error #1009: Cannot access a property or method of a null object reference. 
     at view::ScoreBoard/setChipCount()[C:\Flex Builder 3\StackOverflowQuestion\src\view\ScoreBoard.as:32] 
     at model::MainDeckScoreBoard()[C:\Flex Builder 3\StackOverflowQuestion\src\model\MainDeckScoreBoard.as:21] 
     at model::MainDeckScoreBoard$cinit() 
     at global$init()[C:\Flex Builder 3\StackOverflowQuestion\src\model\MainDeckScoreBoard.as:5] 
     at main()[C:\Flex Builder 3\StackOverflowQuestion\src\main.mxml:13] 
     at _main_mx_managers_SystemManager/create() 
     at mx.managers::SystemManager/initializeTopLevelWindow()[C:\autobuild\3.2.0\frameworks\projects\framework\src\mx\managers\SystemManager.as:3188] 
     at mx.managers::SystemManager/ http://www.adobe.com/2006/flex/mx/internal::docFrameHandler()[C :\autobuild\3.2.0\frameworks\projects\framework\src\mx\managers\SystemManager.as:3064] 
     at mx.managers::SystemManager/docFrameListener()[C:\autobuild\3.2.0\frameworks\projects\framework\src\mx\managers\SystemManager.as:2916]

はmain.mxmlです：ここでは

<?xml version="1.0"?> 
    <mx:Application 
     xmlns:mx="http://www.adobe.com/2006/mxml" 
     creationComplete="initApp()" 
    > 
     <mx:Script> 
      <![CDATA[ 
       import model.MainDeckScoreBoard; 

       public var _mainDeckScoreBoard:MainDeckScoreBoard = MainDeckScoreBoard.instance; 

       private function initApp():void { 
        this.addChild(_mainDeckScoreBoard); 
       } 
      ]]> 
     </mx:Script> 
    </mx:Application> 

はMainDeckScoreBoard.asです：ここでは

package model { 
    import view.ScoreBoard; 

    [Bindable] 
    public dynamic class MainDeckScoreBoard extends ScoreBoard { 

     /** Storage for the singleton instance. */ 
     private static const _instance:MainDeckScoreBoard = new MainDeckScoreBoard(SingletonLock); 

     /** Provides singleton access to the instance. */ 
     public static function get instance():MainDeckScoreBoard { 
      return _instance; 
     } 

     public function MainDeckScoreBoard(lock:Class) { 
      super(); 
      // Verify that the lock is the correct class reference. 
      if (lock != SingletonLock) { 
       throw new Error("Invalid Singleton access. Use MainDeckScoreBoard.instance."); 
      } 
      this.setChipCount("0"); 
     } 

    } // end class 
} // end package 

class SingletonLock { 
} // end class 

はScoreBoard.asです：

package view { 
    import mx.containers.HBox; 
    import view.ScoreBoardLabel; 
    import view.ChipCountContainer; 
    import view.CardRankList; 

    public dynamic class ScoreBoard extends HBox { 

     /** The chip count. */ 
     public var _chipCount:ChipCountContainer; 

     public function ScoreBoard() { 

      super(); 

      this.width = 489; 
      this.height = 40; 
      this.setStyle("horizontalScrollPolicy", "off"); 
     } 

     override protected function createChildren():void { 

      super.createChildren(); 

      if(!_chipCount) { 
       _chipCount = new ChipCountContainer(); 
       this.addChild(_chipCount); 
      } 
     } 

     public function setChipCount(labelText:String):void { 
      _chipCount._chipCountLabel.text = labelText; 
      invalidateDisplayList(); 
     } 
    } 
} 

ここにChipCountContainer.as：

package view { 
    import mx.containers.Canvas; 

    public dynamic class ChipCountContainer extends Canvas { 

     /** The label. */ 
     public var _chipCountLabel:ChipCountLabel; 

     public function ChipCountContainer() { 

      super(); 

      this.width = 20; 
      this.height = 20; 
     } 

     override protected function createChildren():void { 

      super.createChildren(); 

      if(!_chipCountLabel) { 
       _chipCountLabel = new ChipCountLabel(); 
       this.addChild(_chipCountLabel); 
      } 
     } 
    } 
} 

子供の作成ダンスを実行している間に、私は物事を体系的に移動し、無効表示リストの香を振ったが、私は完全に自分自身を混乱させるだけで成功した。私は同様の構造のためにFlexライブラリを検索しました。それは私にはうまく見えますが、私はコンセプトを得ていないと思います。

Answer 1

私はインスタンス化の順序を混乱させると思います。あなたがコンポーネントの子が初期化された後setChipCountを使用したい場合はつまり、あなたはすなわち、火にinitializeイベントを待つ必要があります：コンポーネントのインスタンスのライフサイクルのより詳細な説明については、この日干しのために

public dynamic class MainDeckScoreBoard extends ScoreBoard { 

    ... 

     public function MainDeckScoreBoard(lock:Class) { 
      super(); 
      // Verify that the lock is the correct class reference. 
      if (lock != SingletonLock) { 
       throw new Error("Invalid Singleton access. Use MainDeckScoreBoard.instance."); 
      } 

      // wait for the children to be created 
      addEventListener(FlexEvent.INITIALIZE, onInitialize); 
     } 

     // executes when the children of this component have been created 
     private function onInitialize(event:FlexEvent):void { 
      this.setChipCount("0"); 
     } 

    } // end class 

docは役に立ちます：

http://livedocs.adobe.com/flex/3/html/help.html?content=components_06.html