NullReferenceException in C#

Unity Engine
1

Hi, guys! I’m starting to develop in Unity and I came across this error and I don’t know how to solve it:
"NullReferenceException: Object reference not set to an instance of an object
BulletSetup.Start () (at Assets/Scripts/BulletSetup.cs:54)"

BulletSetup.cs

public class BulletSetup : MonoBehaviour {

    private float xVelocity;
    private float yVelocity;
    private float shotAngle;

    private float xWindVelocity;
    private float yWindVelocity;
    private float windAngle;

    private float xAirDrag;
    private float yAirDrag;
    private float airDragAngle;

    private int playerTurn;
    public GameObject velocityInfo;
    public GameObject windInfo;

    void Start () {
        playerTurn = windInfo.GetComponent<GameSetup> ().playerTurn;

        xWindVelocity = windInfo.GetComponent<GameSetup> ().xWindSpeed;
        yWindVelocity = windInfo.GetComponent<GameSetup> ().yWindSpeed;

        xAirDrag = windInfo.GetComponent<GameSetup> ().xAirDrag;
        yAirDrag = windInfo.GetComponent<GameSetup> ().yAirDrag;

        shotAngle = shotAngle * Mathf.Deg2Rad;

        if (playerTurn == 1) {
            Debug.Log (playerTurn);

            xVelocity = velocityInfo.GetComponent<Player1Setup> ().shotVelocity;
            shotAngle = velocityInfo.GetComponent<Player1Setup> ().shotAngle;

            shotAngle = shotAngle * Mathf.Deg2Rad;

            xVelocity = xVelocity + xWindVelocity - xAirDrag;
            yVelocity = Mathf.Tan (shotAngle) * xVelocity + yWindVelocity - yAirDrag;
           
            rigidbody2D.AddForce (new Vector2 (xVelocity, yVelocity));

        }

        if (playerTurn == 2) {
            Debug.Log (playerTurn);

            xVelocity = velocityInfo.GetComponent<Player2Setup> ().shotVelocity;
            shotAngle = velocityInfo.GetComponent<Player2Setup> ().shotAngle;
           
            shotAngle = shotAngle * Mathf.Deg2Rad;

            xVelocity = -xVelocity + xWindVelocity + xAirDrag;
            yVelocity = Mathf.Tan (shotAngle) * xVelocity + yWindVelocity - yAirDrag;

            rigidbody2D.AddForce (new Vector2 (xVelocity, yVelocity));
        }
    }
}

I don’t understand why it works for playerTurn == 1 but it does not work for playerTurn == 2.

2

It looks like your trying to access the component Player2Setup but you get null if it’s not attached to velocityInfo.

3

Probably what RSG sayed…try to check if your Player2Setup component is not null, something like this:

        if (playerTurn == 2)
            Debug.Log (playerTurn);

        Player2Setup p2 = velocityInfo.GetComponent<Player2Setup> ();

        if(p2 == null)
            Debug.LogError("Player 2 Component is null!!");
        else
        {
            //Your code here...
        }
4

Thanks, velocityInfo was receiving the GameObject of Player 1 and Player 1 indeed doesn’t have Player2Setup.