错误1009：无法访问空引用的属性或方法

Question

我是第一次遇到问题的海报。我的队友和我正在做一个游戏制作项目。它是一个简单的捕捉游戏，只有在失败之后才有效：

TypeError: Error #1009: Cannot access a property or method of a null object reference.
at catcher_fla::MainTimeline/gameLoop()
at flash.utils::Timer/_timerDispatch()
at flash.utils::Timer/tick()

我不是我们团队中的脚本编写者，但是当我查找它时我看到了这一点，据我所知，我们在gameLoop中有一个问题，使用timerDispatch（）函数和tick （）函数。

currentSceneName = "GamePlay";

character.gotoAndPlay("idle")



import flash.events.KeyboardEvent;
import flash.events.TimerEvent;
import flash.utils.Timer;
import flash.display.DisplayObject;
import flash.events.MouseEvent;

//VAR
var speed:Number = 2;
var score:Number = 0;
var life:int = 3;

updateLifeBar();


var isWalkingAnimation:Boolean=false;
var isRight:Boolean = false;
var isLeft:Boolean = false;
var isUp:Boolean = false;
var isDown:Boolean = false;
var isZ:Boolean = false;
var isC:Boolean = false;



var gameState:String = "Off";

playButton.addEventListener(MouseEvent.CLICK, clickPlay);

function clickPlay(event:MouseEvent):void {
    stage.addEventListener(KeyboardEvent.KEY_DOWN, pressKey);
    stage.addEventListener(KeyboardEvent.KEY_UP, liftKey);
    playButton.removeEventListener(MouseEvent.CLICK, clickPlay);
    removeChild(playButton);
    gameState = "On";
    spawnTimer.start();
}

stage.addEventListener(KeyboardEvent.KEY_DOWN, pressKey);
//PRESSKEY
function pressKey(event:KeyboardEvent):void {
    if (isWalkingAnimation == false){
        isWalkingAnimation = true;
        character.gotoAndPlay("walk")
    }

    if(event.keyCode == Keyboard.RIGHT){
        isRight = true;
    }

    if(event.keyCode == Keyboard.LEFT){
        isLeft = true;
    }

    if(event.keyCode == Keyboard.UP){
        isUp = true;
    }

    if(event.keyCode == Keyboard.DOWN){
        isDown = true;
    }

    if(event.keyCode == Keyboard.Z){
        isZ = true;
    }

    if(event.keyCode == Keyboard.C){
        isC = true;
    }

}

stage.addEventListener(KeyboardEvent.KEY_UP, liftKey);
//LIFTKEY
function liftKey(event:KeyboardEvent):void {

    if (isWalkingAnimation == true){
        isWalkingAnimation = false;
        character.gotoAndPlay("idle")
    }

    if(event.keyCode == Keyboard.RIGHT){
        isRight = false;
    }
    if(event.keyCode == Keyboard.LEFT){
        isLeft = false;
    }
    if(event.keyCode == Keyboard.UP){
        isUp = false;
    }

    if(event.keyCode == Keyboard.DOWN){
        isDown = false;
    }
    if(event.keyCode == Keyboard.Z){
        isZ = false;
    }
    if(event.keyCode == Keyboard.C){
        isC = false;
    }

}

var joshsTimer:Timer = new Timer(16);
joshsTimer.addEventListener(TimerEvent.TIMER, gameLoop);
joshsTimer.start();

//GAMELOOP
function gameLoop(event:TimerEvent):void {
    if(isLeft == true && character.x > (0 + character.width * .55)){
        character.scaleX = -.80;
        character.x -= speed;
    }
    if(isRight == true && character.x < (stage.stageWidth - character.width * .58)){
        character.scaleX = .80;
        character.x += speed;
    }
    if(isUp == true && character.y > (0 + character.height * 2)){
        character.y -= speed;
    }
    if(isDown == true && character.y < (stage.stageHeight - character.height * .25)){
        character.y += speed;
    }
    if(isZ == true && character.x >(0 + character.width * .55)){
        character.scaleX = -.80;
        character.x -= speed;
    }
    if(isC == true && character.x < (stage.stageWidth - character.width * .58)){
        character.scaleX = .80;
        character.x += speed;
    }

///////////////Collides with Players Basket//////////////////

    for each(var joshBanana:Banana in bananaArray){
        joshBanana.y = joshBanana.y + (2.5);

        if(joshBanana.hitTestObject(character.activePoint)){
            score += 100;
            var bananaToBeRemoved:Banana = joshBanana;
            bananaArray.splice(joshBanana, 1);
            removeChild(bananaToBeRemoved);
            doGoodThings();
        }
    }
    for each(var joshCandy:Candy in candyArray){
        joshCandy.y = joshCandy.y + (2.5);

        if(joshCandy.hitTestObject(character.activePoint)){

            var candyToBeRemoved:Candy = joshCandy;
            candyArray.splice(joshCandy, 1);
            removeChild(candyToBeRemoved);
            doBadThings();

        }
    }
    for each(var joshApple:Apple in appleArray){
        joshApple.y = joshApple.y + (2.5);

        if(joshApple.hitTestObject(character.activePoint)){
            score += 100;
            var appleToBeRemoved:Apple = joshApple;
            appleArray.splice(joshApple, 1);
            removeChild(appleToBeRemoved);
            doGoodThings();
        }
    }
    for each(var joshChocolate:Chocolate in chocolateArray){
        joshChocolate.y = joshChocolate.y + (2.5);

        if(joshChocolate.hitTestObject(character.activePoint)){

            var chocolateToBeRemoved:Chocolate = joshChocolate;
            chocolateArray.splice(joshChocolate, 1);
            removeChild(chocolateToBeRemoved);
            doBadThings();


        }

    }

////////////////////////If falls below Stage/////////////////////   

    for(var i:uint = 0; i < bananaArray.length;i++){
        if(bananaArray[i].y > stage.stageHeight){
            var fallBananaToBeRemoved:DisplayObject = bananaArray[i];
            bananaArray.splice(i, 1);
            removeChild(fallBananaToBeRemoved);

        }
    } 
    for(i = 0; i < candyArray.length;i++){
        if(candyArray[i].y > stage.stageHeight){
            var fallCandyToBeRemoved:DisplayObject = candyArray[i];
            candyArray.splice(i, 1);
            removeChild(fallCandyToBeRemoved);

        }
    }
    for(i = 0; i < appleArray.length;i++){
        if(appleArray[i].y > stage.stageHeight){
            var fallAppleToBeRemoved:DisplayObject = appleArray[i];
            appleArray.splice(i, 1);
            removeChild(fallAppleToBeRemoved);

        }
    }
    for(i = 0; i < chocolateArray.length;i++){
        if(chocolateArray[i].y > stage.stageHeight){
            var fallChocolateToBeRemoved:DisplayObject = chocolateArray[i];
            chocolateArray.splice(i, 1);
            removeChild(fallChocolateToBeRemoved);

        }
    }

}

var bananaArray:Array = new Array();
var candyArray:Array = new Array();
var appleArray:Array = new Array();
var chocolateArray:Array = new Array();


var spawnTimer:Timer = new Timer(1000);
spawnTimer.addEventListener(TimerEvent.TIMER, spawnBanana);
spawnTimer.stop();

var numOfFruitToSpawn:Number = 1;

function spawnBanana(event:TimerEvent):void {


    for(var i:uint = 0; i < numOfFruitToSpawn; i++){
        var randomFruit:Number = randomNumber(1,4);

        if(randomFruit == 1){
            var newBanana:Banana = new Banana();
            addChild(newBanana);
            bananaArray.push(newBanana);

            newBanana.x = randomNumber(0, stage.stageWidth - newBanana.width)
            newBanana.y = 0 - newBanana.height;
        } 
        else if(randomFruit == 2){
            var newCandy:Candy = new Candy();
            addChild(newCandy);
            candyArray.push(newCandy);

            newCandy.x = randomNumber(0, stage.stageWidth - newCandy.width)
            newCandy.y = 0 - newCandy.height;
        }
        else if(randomFruit == 3){
            var newChocolate:Chocolate = new Chocolate();
            addChild(newChocolate);
            chocolateArray.push(newChocolate);

            newChocolate.x = randomNumber(0, stage.stageWidth - newChocolate.width)
            newChocolate.y = 0 - newChocolate.height;
        }
        else if(randomFruit == 4){
            var newApple:Apple = new Apple();
            addChild(newApple);
            appleArray.push(newApple);

            newApple.x = randomNumber(0, stage.stageWidth - newApple.width)
            newApple.y = 0 - newApple.height;

        }



    }

}



function doGoodThings():void {
    trace("GOT SOME GOOD!");
    joshScore.text = "SCORE: " + String(score);

}

function doBadThings():void {
    life--;

    trace("Bad JuJu");
    updateLifeBar();

    if(life == 0){
        endGame();
        gotoAndStop("1", "MainMenu");
    }
}

function endGame():void {
    stage.removeEventListener(KeyboardEvent.KEY_DOWN, pressKey);
    stage.removeEventListener(KeyboardEvent.KEY_UP, liftKey);
    //playButton.removeEventListener(MouseEvent.CLICK, clickPlay); 
    //Altered line 307 to playButton.removeEventLitener from addEventListener
    //addChild(playButton); readded this line
    gameState = "Off";
    spawnTimer.stop();
}

function updateLifeBar():void {
    if(life > 0){
        lifeBar.gotoAndStop(life);
    } else if(life <= 0){
        lifeBar.gotoAndStop(4);
    }
}

function randomNumber(min:Number, max:Number):Number {
    return Math.floor(Math.random() * (1 + max - min) + min);
}