AS3, removing objects from list error

Question

I have a list of objects and I'm attempting to iterate through the list and check for a collision, at which point a motion tween will play at the end of which the function to remove the object will be executed.

stage.addEventListener(Event.ENTER_FRAME, hitTest);
function hitTest(e:Event ):void
{
    for each (bullet in bullets)
    {
        if (bullet.parent == null)
        {
            bullets.splice(bullets.indexOf(bullet),1);
        }
        else if (bullet.hitTestObject(shark))
        {
            trace("HIT1");
            bullet.gotoAndPlay(2); //part that's giving me trouble
            bullets.splice(bullets.indexOf(bullet),1);
            trace("HIT");
        }
        else
        {
            for each (enemy in enemies)
            {
                if (enemy !=null && bullet.hitTestObject(enemy))
                {
                    enemies.splice(enemies.indexOf(enemy),1);
                    enemy.remove();
                    enemy = null;
                    bullets.splice(bullets.indexOf(bullet),1);
                    bullet.remove();
                    break;
                }
            }
        }
       }

going through list testing various things.

at the end of the motion tween setup for the bullet object of the Bullet class

stop();
this.remove();

this is the remove function in the bullet class

public function remove() {
    parent.removeChild(this);
    this.removeEventListener(Event.ENTER_FRAME, moveMe);
}

specific error

TypeError: Error #1009: Cannot access a property or method of a null object reference.
at Bullet/remove()
at Bullet/frame20()

frame 20 is the last frame of the motion tween and has the code above^^

thanks for any help.

Community · Accepted Answer · 2017-05-23 11:58:28Z

2

Removing items from an array you are iterating over changes the length of the array and can lead to errors. Options are to iterate over the array backwards or have a local temporary array that you push the indices of your "hits" into and then do the removal from your main array after the main for loop is complete and then iterate over the temps array.

See here and here for similar issues with discussion and solution examples.

edited May 23, 2017 at 11:58

CommunityBot

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answered Nov 16, 2014 at 19:01

spring

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