[Solved] Adding a GameObject to a <List> of objects

Hello,

So I am pretty new to Unity and learning as I go. I have a lot of C++ game development experience using a very protracted engine, so moving to Unity is quite fresh!

What I am trying to do:

• Add a new aircraft to the game
• Push the instanciated aircraft onto a list
• Access all instanciated aircrafts to run their methods which makes the AI work

The Code:

public class GameManager : MonoBehaviour {​

// store a list of aircraft
List<GameObject> aircrafts;

void Start () {

// spawn!

// load an aircraft prefab as a GameObject initially
gameobj = (GameObject)Instantiate(Resources.Load("Aircraft"));

// give the gameobj the class Aircraft to access its member functions
Aircraft aircraft = gameobj.AddComponent<Aircraft>();
m_aircrafts.Add(aircraft); // push to the List

int i = 0;

foreach (GameObject ac in aircrafts)
{

Debug.Log("Hello, you are: " + i);
i++;​

}​

}​

}​

However the line `aircrafts.Add(aircraft);` gives the error: "object instance not set to an instance of an object". From Google it looks like the object aircraft doesn't exist? I'm not entirely sure why it wont push the aircraft to the list.

 

http://forum.unity3d.com/threads/using-code-tags-properly.143875/

you haven't "created the list", all you've said is "I'm going to have a list called dave".

you need

Code (csharp):

1.  
2. aircrafts = new List<GameObject>();
3.  

somewhere before you try to do anything with it.

close, the list "aircrafts" doesn't exist so you can't add anything to it yet. Null exception errors are usually complaining about the object before the "." rather than the thing after. You can add null to a list quite happily, you can't add something to a null list.

 

Thanks for the reply! Kicking myself for missing that one, thank you!

 

Oh. My. GOODNESS
I've been going through so many threads looking for some clever quirk or nuance to Unity I don't know about, reorganized my code every which way scratching a new hole in my head for over two hours and THIS was the problem?!

*head-desk*

Thank you in 2022, LeftyRighty!