AS3：另一个 1009 错误：空对象在哪里

Question

我有1009个错误，但我找不到空对象。有人能给我指一下吗？

[故障]异常，信息=类型错误：错误#1009：无法访问null对象引用的属性或方法。

[故障]异常，信息=类型错误：错误#1009：无法访问属性或方法的空对象引用。在Square/draw(([/Users/si/Dropbox/ac3/Square/src/Square.as:21]Start/drawSquare(([/Users/si/Dropbox/ac3/square/src/Start.as:35]starling.events:EventDispatcher/invokeEvent(([/Users/redge/Dropbox/Development/sttaring/sttaring/src/sttaring/events/EventDispatcher.as:146]在starling.events:EventDispatchEvent(([/Users/redge/Dropbox/Development/sttaring/sttaring/src/sttaring/events/EventDispatcher.as:117]在starling.display:：DisplayObject/dispatchEvent(([/Users/redge/Dropbox/Development/sttaring/sttaring/src/sttaring/deisplay/DisplayObject.as:398]在starling.display:：DisplayObjectContainer/broadcastEvent(([/Users/redge/Dropbox/Development/staring/staring/src/staring/deisplay/DisplayObjectContainer.as:379]在starling.display:：DisplayObjectContainer/broadcastEventWith(([/Users/redge/Dropbox/Development/staring/staring/src/staring/deisplay/DisplayObjectContainer.as:389]在starling.display:：DisplayObjectContainer/addChildAt(([/Users/redge/Dropbox/Development/staring/staring/src/staring/deisplay/DisplayObjectContainer.as:135]在starling.core:：starling/initializeRoot(([/Users/redge/Dropbox/Development/sttaring/sttaring/src/sttaring/core/starling.as:439]在starling.core:：starling/initialize(([/Users/redge/Dropbox/Development/sttaring/sttaring/src/sttaring/core/starling.as:410]在starling.core:：starling/onContextCreated(([/Users/redge/Dropbox/Development/sttaring/sttaring/src/sttaring/core/starling.as:649]

这是星光计划，它很重要。

这是代码：

package {
   import starling.display.*;
   import com.greensock.TweenLite;
   import com.greensock.easing.Linear;
public class Square extends Sprite implements ISquare {
    public const square:Quad = new Quad(100, 100);
    private var direction:Boolean;
    private var stopped:Boolean;
    private var speed:int;
    public function Square() {
    }
    public function draw():void{
        addChild(square);
        square.color = 0x4500FF;
        direction = new Boolean(true);
        stopped = new Boolean(false);
        speed = new int(stage.stageHeight);
        trace("vars init complete");
        down();
    }
   ...

以下是dropbox上的全部酸味：https://www.dropbox.com/sh/9x2q93o2ff1fsna/AADVJgt5nipDE1pdkgozkOc1a

Answer 1

好吧，让我们来看看相关的代码。。。

启动类

//stuff omitted like imports
public class Start extends Sprite {
    public var viewport:Quad = new Quad(1,1);
    private var swipe:SwipeGesture;
    private var call:Square = new Square();
    public function Start() {
        super();
        addEventListener(Event.ADDED_TO_STAGE, drawSquare);
    }
    private function drawSquare(event:Event):void {
        removeEventListener(Event.ADDED_TO_STAGE, drawSquare);
        viewport.width = stage.stageWidth;
        viewport.height = stage.stageHeight;
        viewport.color = 0x414141;
        addChild(viewport);
        swipe = new SwipeGesture(viewport);
        swipe.addEventListener(GestureEvent.GESTURE_RECOGNIZED, onSwipe);
        trace("gesture listener added");
        call.draw();
    }
    //stuff omitted
}

方形

//imports omitted
public class Square extends Sprite implements ISquare {
    public const square:Quad = new Quad(100, 100);
    private var direction:Boolean;
    private var stopped:Boolean;
    private var speed:int;
    public function Square() {
    }
    public function draw():void{
        addChild(square);
        square.color = 0x4500FF;
        direction = new Boolean(true);
        stopped = new Boolean(false);
        speed = new int(stage.stageHeight);
        trace("vars init complete");
        down();
    }
    //stuff omitted
}

当我手动读取您的代码时，我看到发生了以下情况：

• Start.constructor添加事件侦听器
• eventListener触发器，start.drawSquare
• 添加视口，使用滑动功能
• 绘制正方形
• Square.draw称为
• 方形为自身添加四边形
• 设置一些颜色和变量
• 指向真
• 停止为false
• 至stage.stageHeight的速度

等等，stage？CCD_ 4在CCD_。我认为它是无效的。事实上，当您查看错误的堆栈跟踪时，您可以看到这一点。它说at Square/draw() in /Users/si/Dropbox/ac3/square/src/Square.as:21出了问题。Square.as的第21行是speed = new int(stage.stageHeight);。这表明该行中提到的对象之一为空或未定义。通过消除过程，我们可以看到speed已经被声明，并且正在被分配，因此是不相关的；int类已定义，否则编译会出错；并且我们只剩下CCD_ 9为空或者CCD_。

文档中说Stage.stageHeight是一个int。它是stage的一个属性，由于它是一个基元类型，所以它从不为null或以其他方式未定义(无论如何，在actionscript中都不是(。因此，留给我们的是stage：Start的call实例从未添加到stage中，因此stage为null，因此它在上为null

speed = new int(stage.stageHeight)

要解决此问题，请将Square的draw函数传递给stage。。。或者，这似乎是更好的解决方案，考虑到您想要做的事情，在绘制之前将调用(即Square实例(添加到stage。