動態地將舞臺上的MovieClip實例放在舞臺上（AS3）

Question

我試圖在舞臺上動態地放置MovieClip的實例。 收到一個錯誤：

TypeError: Error #2007: Parameter child must be non-null. 
    at flash.display::DisplayObjectContainer/addChild() 

的ActionScript：

  // properties in class ---------- 
     var circle_ary:Array = new Array; 
     var circ_num:int;//number of circles on the stage 

     // dynamically place MovieClip instances on the stage ---------- 
     // inside Constructor function of class 
     var circ_num:int=20;//number of circles on the stage 

     for(var i=0; i<circ_num; i++) { 
      circle_ary[i] = new Circle(); //linkage in the library 
      addChild(Circle[i]); 
     } 

Answer 1

應該

addChild(circle_ary[i]);