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这是我得到的错误：

TypeError: Error #1009: Cannot access a property or method of a null object reference. at     ICA_v7_fla::MainTimeline/addEgg()
at Function/http://adobe.com/AS3/2006/builtin::apply()
at SetIntervalTimer/onTimer()
at flash.utils::Timer/_timerDispatch()
at flash.utils::Timer/tick()

看不到我哪里出错了 - 有人可以指出我试图引用空对象引用的地方吗:)

我的 AS 的其余部分内容如下：

import flash.events.Event;
import flash.utils.Timer;
import flash.events.TimerEvent;
//Set as a variable so that it can be changed at a later
//date so that the user level can change (if necessary).
var eggMoveSpeed=6;
var Score=0;
var ScoreValue=10;
var Level=1;
var NextLevel=100;
var EggCount=0;
var EggMax=15;

btn.addEventListener(MouseEvent.CLICK, scorer);
function scorer(e:Event):void{
//Add to the score.
Score=Score+10;
//Display score in text box.
scoreText.text=Score;
}
var eggAdd = setInterval(addEgg,2000);
function addEgg(){
//Add to the egg count (to ensure maximum is not exceeded).
EggCount=EggCount+1;
if (EggCount<=EggMax){
//Create an object of the egg_mc from the egg class.
var egg:egg_mc = new egg_mc();
//Set the Max and Min WIDTH positions.
var maxWidth = 452;
var minWidth = 98;
//Randomize the position of the egg on the screen - with thanks to     http://www.kirupa.com/developer/actionscript/tricks/random.htm
var positionX = Math.floor(Math.random()*(1+maxWidth-minWidth))+minWidth; 
//Position the egg on the stage, and add it to the screen
egg.y=400;
egg.x=positionX;
//Add the egg to the stage.
stage.addChild(egg);
//Add a moving loop to the egg.
egg.addEventListener(Event.ENTER_FRAME, loop);
}else{
    clearInterval(eggAdd);
}
    function loop(e:Event):void{
    //Move the egg up the screen.
    egg.y-=eggMoveSpeed;
    //Check to see if egg has got to the top of the screen - if so, then move the object to the bottom.
    if (egg.y<-100){
        egg.y=400;
    }
}
//Add an event listener to the egg, to see if it has been clicked.
egg.addEventListener(MouseEvent.CLICK, clickedEgg);

function clickedEgg(e:Event):void{
//http://asgamer.com/2009/flash-game-design-basics-adding-library-objects-to-stage-with-as3
//Create an object of the brokenEgg_mc from the broken egg class.
var brokenEgg:brokenEgg_mc = new brokenEgg_mc();
//Position the brokenEgg image wherever the egg Image was.
brokenEgg.y=egg.y;
brokenEgg.x=egg.x;
//Add brokenEgg to stage, and remove the egg image.
stage.addChild(brokenEgg);
stage.removeChild(egg);

//Add to the score.
Score=Score+ScoreValue;
//Display score in text box.
scoreText.text=Score;
//Set LevelCheck Variable to 0 - to recalculate correctly.
var LevelCheck = 0;
//Check the level that the user is currently on by dividing the score by the next level required score.
LevelCheck=Score/NextLevel;
//Setup a variable to use for the actual level to display.
var ActualLevel=0;
//Check to see if the LevelCheck variable has come back less than 1 (i.e. 0.1 or a score of 10).
if (LevelCheck < 1){
    //If yes, then set the level to 1, as user is still on level 1.
    ActualLevel=0;
} else {
    //If not, then round down to the lowest level (1.9 is still level 1!).
    ActualLevel=Math.floor(LevelCheck);
}
//Display the Lowest Level to the user.
levelText.text=ActualLevel;
}}

显然，计时器事件循环直到舞台上有 15 个鸡蛋，然后间隔应该停止运行——但这会产生错误。

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1 回答 1

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您的egg变量是函数范围的，即它在addEgg()函数中定义，但您引用egg内部的clickedEggand loop，它没有实际访问egg' 值的权限。此外，如果有多个鸡蛋，您打算如何跟踪点击了哪个鸡蛋等？至少，使用e.targetinclickedEgg函数找出点击了哪个鸡蛋，并且不要忘记清除事件侦听器。

function addEgg():void {
    if (EggCounter>=EggMax) return; // why adding eggs if there are too many?
    var egg:egg_mc=new egg_mc();
    // rest of code intact
}
function loop(e:Event):void {
    var egg:egg_mc=(e.target as egg_mc);
    if (!egg) return; // loop is for eggs only
    // rest of function intact
}
function clickedEgg(e:MouseEvent):void {
    var egg:egg_mc=(e.target as egg_mc);
    if (!egg) return;
    // rest of function intact, as we now have a valid egg link
    egg.removeEventListener(Event.ENTER_FRAME,loop);
    egg.removeEventListener(MouseEvent.CLICK,clickedEgg);
    // clear listeners. These are persistent until removed manually!
}
于 2013-04-18T13:57:10.183 回答