我目前在引用导出时为null的对象时遇到了一些麻烦。基本上我希望Document Class运行另一个类的代码，该类是MovieClip的类，而不会在输出面板中的任何地方弹出 Error 1009 。
这是我正在尝试运行的子类：
package
{
import flash.display.*;
import flash.events.*;
import Document;
import RestartButton;
public class McMain extends MovieClip
{
public var document:Document;
public var leftKeyDown:Boolean = false;
public var rightKeyDown:Boolean = false;
public var upKeyDown:Boolean = false;
public var downKeyDown:Boolean = false;
public var onGround:Boolean = true;
public var xSpeed:Number = 0;
public var ySpeed:Number = 0;
public var mainSpeed:Number = 3.75;
public var frictionPower:Number = 0.9;
public var jumpPower:Number = 13;
public var gravityPower:Number = 0.5;
public var terminalVelocity:Number = 75;
public function McMain()
{
this.addEventListener(Event.ADDED_TO_STAGE, initMcMain);
// constructor code
}
public function initMcMain(event:Event)
{
addEventListener(KeyboardEvent.KEY_DOWN, checkKeysDown);
addEventListener(KeyboardEvent.KEY_UP, checkKeysUp);
addEventListener(Event.ENTER_FRAME, hitTest);
addEventListener(Event.ENTER_FRAME, Main);
}
public function Main(event:Event):void
{
this.moveCharacter();
this.dynamicMovement();
}
public function checkKeysDown(event:KeyboardEvent):void
{
if (event.keyCode == 37)
{
this.leftKeyDown = true;
}
if (event.keyCode == 38)
{
this.upKeyDown = true;
}
if (event.keyCode == 39)
{
this.rightKeyDown = true;
}
if (event.keyCode == 40)
{
this.downKeyDown = true;
}
}
public function checkKeysUp(event:KeyboardEvent):void
{
if (event.keyCode == 37)
{
this.leftKeyDown = false;
}
if (event.keyCode == 38)
{
this.upKeyDown = false;
}
if (event.keyCode == 39)
{
this.rightKeyDown = false;
}
if (event.keyCode == 40)
{
this.downKeyDown = false;
}
}
public function moveCharacter():void
{
if (this.leftKeyDown)
{
this.xSpeed -= this.mainSpeed;
if (this.onGround)
{
this.scaleX = -1;
}
}
if (this.rightKeyDown)
{
this.xSpeed += this.mainSpeed;
if (this.onGround)
{
this.scaleX = 1;
}
}
if (this.leftKeyDown && this.onGround || this.rightKeyDown && this.onGround)
{
this.gotoAndStop(2);
}
if (this.currentFrame == 2)
{
if (! this.leftKeyDown && ! this.rightKeyDown)
{
this.gotoAndStop(3);
}
}
if (this.currentFrame == 3)
{
if (this.skidAnimation.currentFrame == this.skidAnimation.totalFrames)
{
this.gotoAndStop(1);
}
}
if (this.upKeyDown)
{
this.ySpeed -= this.jumpPower;
}
if (this.upKeyDown && this.leftKeyDown)
{
this.ySpeed -= 0;
this.xSpeed -= 10;
}
if (this.upKeyDown && this.rightKeyDown)
{
this.ySpeed -= 0;
this.xSpeed += 10;
}
if (this.xSpeed > 3 && ! onGround || this.xSpeed < -3 && ! onGround)
{
if (this.currentFrame == 2)
{
this.gotoAndStop(5);
}
}
if (this.ySpeed < -0.5 && ! onGround)
{
this.gotoAndStop(4);
}
else if (this.ySpeed > 0.5 && ! onGround)
{
this.gotoAndStop(5);
}
if (this.currentFrame == 5 && onGround)
{
this.gotoAndStop(1);
}
//if (! leftKeyDown && ! rightKeyDown && ! upKeyDown)
//{
//mcMain.gotoAndStop(1);
//}
}
public function dynamicMovement():void
{
if (onGround)
{
this.x += this.xSpeed;
this.xSpeed *= this.frictionPower;
}
else
{
this.x += this.xSpeed;
this.xSpeed *= (this.frictionPower + 0.09);
}
if (this.xSpeed > 7)
{
this.xSpeed = 7;
}
if (this.xSpeed < -7)
{
this.xSpeed = -7;
}
this.y += this.ySpeed;
this.ySpeed += this.gravityPower;
if (this.ySpeed > this.terminalVelocity)
{
this.ySpeed = this.terminalVelocity;
}
}
public function hitTest(event:Event)
{
//spawnArea.visible = false;
this.mcMainHitArea.visible = false;
this.document.levelChange.wallCollision.visible = false;
//^^^^^^^^^^^^^^^^^^^^^^^^^^
//Error 1009 appearing here!
this.document.levelChange.deathArea.visible = false;
this.document.levelChange.goalArea.goalHitArea.visible = false;
while (document.levelChange.wallCollision.hitTestPoint(this.x, this.y, true))
{
this.y = this.y - 0.5;
this.ySpeed = 0;
}
while (document.levelChange.wallCollision.hitTestPoint(this.x, this.y - 24, true))
{
this.y = this.y + 0.5;
this.ySpeed = 0;
}
while (document.levelChange.wallCollision.hitTestPoint(this.x - 12, this.y - 11, true))
{
this.x = this.x + 0.5;
this.xSpeed = 0;
if (! onGround)
{
this.leftKeyDown = false;
}
}
while (document.levelChange.wallCollision.hitTestPoint(this.x + 12, this.y - 11, true))
{
this.x = this.x - 0.5;
this.xSpeed = 0;
if (! onGround)
{
this.rightKeyDown = false;
}
}
if (document.levelChange.wallCollision.hitTestPoint(this.x - 16, this.y - 11, true))
{
if (this.upKeyDown)
{
this.ySpeed -= 10;
this.xSpeed += 50;
}
}
if (document.levelChange.wallCollision.hitTestPoint(this.x + 16, this.y - 11, true))
{
if (this.upKeyDown)
{
this.ySpeed -= 10;
this.xSpeed -= 50;
}
}
if (document.levelChange.wallCollision.hitTestPoint(this.x, this.y, true))
{
if (this.upKeyDown)
{
this.upKeyDown = false;
this.onGround = false;
}
}
if (! document.levelChange.wallCollision.hitTestPoint(this.x, this.y + 1, true))
{
if (! document.levelChange.wallCollision.hitTestPoint(this.x, this.y + 1.5, true))
{
this.upKeyDown = false;
}
if (! document.levelChange.wallCollision.hitTestPoint(this.x, this.y + 5, true))
{
//upKeyDown = false;
onGround = false;
}
}
if (document.levelChange.wallCollision.hitTestPoint(this.x, this.y + 1, true))
{
this.ySpeed = 0;
if (document.levelChange.wallCollision.hitTestPoint(this.x, this.y + 5, true))
{
onGround = true;
}
}
if (document.levelChange.deathArea.hitTestPoint(this.x, this.y + 1, true))
{
this.x = this.x;
this.y = this.y;
}
if (this.hitTestObject(document.levelChange.goalArea.goalHitArea))
{
if (stage.contains(document.level_1))
{
this.removeChild(document.level_1);
//stage.removeEventListener(Event.ENTER_FRAME,hitTest);
}
if (stage.contains(document.spawnArea))
{
this.x = this.x;
this.y = this.y;
}
addChild(document.level_2);
document.level_2.x = -1425;
document.level_2.y = -2550;
}
}
}
}
文件类：
package
{
import flash.events.*;
import flash.display.*;
import flash.geom.Point;
import McMain;
import RestartButton;
import Level_2;
public class Document extends MovieClip
{
public var levelNumber:int = 1;
public var levelChange:Object;
public var levelArray:Array = new Array();
public var collisionArray:Array = new Array();
public var deathAreaArray:Array = new Array();
public var goalAreaArray:Array = new Array();
public var goalHitAreaArray:Array = new Array();
public var mcMain:McMain;
public var restartButton:RestartButton;
public var level_2:Level_2;
public function Document()
{
addEventListener(Event.ADDED_TO_STAGE, init);
mcMain = new McMain();
mcMain.document = this;
restartButton = new RestartButton();
restartButton.document = this;
level_2 = new Level_2();
// constructor code
}
public function init(event:Event)
{
this.levelChange = this.level_1;
}
public function levelHandler(event:Event)
{
this.levelChange = this["level_" + levelNumber];
if (level_2.stage)
{
levelNumber = 2;
//trace(levelChange);
}
for (var i:int = numChildren - 1; i >= 0; i--)
{
var collisionChild:DisplayObject = getChildAt(i);
if (collisionChild.name == "wallCollision")
{
collisionArray.push(collisionChild);
}
var deathAreaChild:DisplayObject = getChildAt(i);
if (deathAreaChild.name == "deathArea")
{
deathAreaArray.push(deathAreaChild);
}
var goalAreaChild:DisplayObject = getChildAt(i);
if (goalAreaChild.name == "goalArea")
{
goalAreaArray.push(goalAreaChild);
}
}
for (var i_2:int = numChildren - 2; i >= 0; i--)
{
var goalHitAreaChild:DisplayObject = getChildAt(i_2);
if (goalHitAreaChild.name == "goalHitArea")
{
goalHitAreaArray.push(goalHitAreaChild);
}
}
}
public function vCamMovement(event:Event):void
{
/*for (var i:int = 0; i < this.numChildren - 1; i++)
{
this.getChildAt(i).x -= xSpeed;
//levelObjects.getChildAt(i).y -= ySpeed;
}*/
level_1.x += stage.stageWidth * 0.5 - mcMain.x;
level_1.y += stage.stageHeight * 0.5 - mcMain.y;
level_2.x += stage.stageWidth * 0.5 - mcMain.x;
level_2.y += stage.stageHeight * 0.5 - mcMain.y;
spawnArea.x += stage.stageWidth * 0.5 - mcMain.x;
spawnArea.y += stage.stageHeight * 0.5 - mcMain.y;
mcMain.x = stage.stageWidth * 0.5;
mcMain.y = stage.stageHeight * 0.5;
}
}
}
编辑：修复了代码中的一个小错误，但代码仍无效。
编辑：
这是调试器输出：
TypeError: Error #1009: Cannot access a property or method of a null object reference. at McMain/hitTest()[C:\Users\*\Desktop\*\Flash\*\McMain.as:186] *= XXXXXXXXXXXX
答案 0 :(得分：0)
两件事。 1，我无法看到你初始化level_1对象的任何地方。第二，你应该将这段代码从构造函数对象中移出到init方法中。
mcMain = new McMain();
mcMain.document = this;
restartButton = new RestartButton();
restartButton.document = this;
原因很简单。您只是创建mcMain，然后将其.document属性设置为“this”。在mcMain中，您引用了mcMain.document.levelChange，但是直到稍后才在init方法中定义document.levelChange。我并不完全相信这绝对是你的问题，但是当你在动态类上访问动态属性时，你真的应该做错误检查。尝试做像
这样的事情if(document != null && document.levelChange != null)
。