NullReferenceException when calling function from another C# class

Unity Engine
1

Hello, i need help with one error in my game, 2D platform for android. I have class for moving objects(traps) which working correctly, then i have class which is called only when i touch my own layer (TeleportLayer) and when i touch this layer then my character is teleported to definet Vector3 position. I want to call function from movingobject class in teleport class, but when i make it, then i get NullReferenceException, don’t know why.

in moving object i have function

public void ResetPositions()
  {
  transform.position = defaultPosition;
  }

and in teleport function i have this

.
.
.
private MoveObject moveObject;

void Start()
  {
  moveObject = GetComponent<MoveObject>();
  textScore = GameObject.Find("ScoreNumber").GetComponent<Text>();
  kamera = GameObject.Find("Kamera").transform;
  }

void Update()
  {
  var pos = bottonPosition;
  pos.x += transform.position.x;
  pos.y += transform.position.y;

  standing = Physics2D.OverlapCircle(pos, collisionRadius, collisionLayer);

  if (standing)
  {
  transform.position = spawnLocation;
  kamera.position = CameraRestartPoint;
  moveObject.ResetPositions();
  restartCount++;
  textScore.text = restartCount.ToString();
  }
  }

How to fix it? Thanks a lot :slight_smile:

2

What does the full error say?

3

Full error is NullReferenceException
Object reference not set to an instance of an object and scriptname with line number and line with error is moveObject.ResetPositions(); (26)

4

So its likely that the GameObject that the script is attached to does not have a MoveObject script attached.
You could add one in the inspector or do it via script. Its also possible that maybe you are querying the wrong GameObject?

5

and can you please tell me how to correctly attach MoveObject script into another one?

what i need to do is call ResetPosition() from class CollisionStateTeleportToStart where i declare MoveObject and GetComponent and function ResetPosition() is declared in MoveObject C# class

6

This is what i have in IDE
This is Empty class where i have traps(quads) as childs Screenshot by Lightshot
And this is teleport script attached on player Screenshot by Lightshot

7

I found a problem, it’s been fixed via moveObject = GameObject.Find(“NameOfObject”).GetComponent();

2 Likes
8

One more question to solve completely this problem, i need to use GameObject.Find to main object and then find all childobjects and make foreach on them, how can i get all childs to array please?

Screenshot by Lightshot → i set GameObject.Find(“Traps”) and then i need to read all childs in this object.

9

Solved :slight_smile:

Solution:

private MoveObject[] moveObject;

void Start()
{
.
.
moveObject = GameObject.Find("Traps").GetComponentsInChildren<MoveObject>();
}

void Update()
{
.
.
foreach (MoveObject item in moveObject)
  {
  item.ResetPositions();
  }
}

Thanks for your time and help how to find null object :slight_smile: THis “querying the wrong GameObject” help me to get solution, when i realize im calling object which i dont have attached to object and i need to call specific via name :slight_smile:

1 Like
10

-Also solved in this way: using the example above:
-instead of this, at line 5:
private MoveObject moveObject;

  • use this:
    private MoveObject moveObject = new MoveObject();