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Question by anthogd · Jun 17, 2020 at 09:55 AM · nullreferenceexceptionlistschildren

List becomes null in Parent when filled in child script,List becomes null within own class after being filled in other class

Dear all,

I am trying to fill a list of Gameobjects that I spawn every X seconds. This list is instantiated in one class (PickUpWeapons) as such:

 public List<GameObject> weaponsToPickUp = new List<GameObject>();     //list of weapons spawned over the course of the game

And in my class where I spawn weapons (SpawnObjects), I fill this list as such: PickUpWeapons pickUp; //reference to pickUpWeapons class

     //instanciate
     private void Start() {
         //generate instance of the pool
         objectPooler = ObjectPooler.Instance;
 
         pickUp = gameObject.AddComponent<PickUpWeapons>();  //instanciate the class
         //pickUp.weaponsToPickUp = new List <GameObject>();
     }
 
     private void FixedUpdate() {
         //only spawn objects if it is time
         if (Time.time > nextSpawnTime) {
             //update next spawn time
             nextSpawnTime = Time.time + spawnRateWeapons;
             //where we spawn the weapons
             float randomXPos = Random.Range(- xMax, xMax);
             whereToSpawn = new Vector2(randomXPos, transform.position.y);
             //generate object
             GameObject bullet = ObjectPooler.Instance.SpawnFromPool("Bullet", whereToSpawn, Quaternion.identity);
             //freeze its position on X only
             bullet.GetComponent<Rigidbody2D>().constraints = RigidbodyConstraints2D.FreezePositionX;
 
             //add weapon generated as a potentially picked up weapon
             pickUp.weaponsToPickUp.Add(bullet);
             Debug.Log(pickUp.weaponsToPickUp.Count);
         }
     }
 }

In this class (SpawnObjects) pickUp.weaponsToPickUp is not empty and the Log does indicate an increase in size of weaponsToPickUp. However, back in PickUpWeapons class, this list is now empty.

Does anyone know what I could do to solve this please?

Best Regards, Anthony Guillard

,Dear all, I have the two following classes, one that creates items and the other that enables the user to pick them up.

In my class PickUpWeapons, I create a list of GameObjects

     public List<GameObject> weaponsToPickUp = new List<GameObject>();     //list of weapons spawned over the course of the game


Which is filled in the class SpawnObjects

     PickUpWeapons pickUp;     //reference to pickUpWeapons class
 
     //instanciate
     private void Start() {
         //generate instance of the pool
         objectPooler = ObjectPooler.Instance;
 
         pickUp = gameObject.AddComponent<PickUpWeapons>();  //instanciate the class
         pickUp.weaponsToPickUp = new List <GameObject>();
     }
 
 
  private void FixedUpdate() {
         //only spawn objects if it is time
         if (Time.time > nextSpawnTime) {
             //update next spawn time
             nextSpawnTime = Time.time + spawnRateWeapons;
             //where we spawn the weapons
             float randomXPos = Random.Range(- xMax, xMax);
             whereToSpawn = new Vector2(randomXPos, transform.position.y);
             //generate object
             GameObject bullet = ObjectPooler.Instance.SpawnFromPool("Bullet", whereToSpawn, Quaternion.identity);
             //freeze its position on X only
             bullet.GetComponent<Rigidbody2D>().constraints = RigidbodyConstraints2D.FreezePositionX;
 
             //add weapon generated as a potentially picked up weapon
             pickUp.weaponsToPickUp.Add(bullet);
 }
 }
 
 }


But when I access again the list weaponsToPickUp in PickUpWeapons (its class), the list is null/empty and does not contain the bullets spawned anymore which is problematic as I cannot detect the collisions afterwards.

Does anyone know how to solve this please?

Best Regards, Anthony Guillard

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