NullReferenceException: Object reference not set to an instance of an object

Questions & Answers
1

The code is to pick up an object which increases the players speed.
maxForwardSpeed is a variable of class characterMotorMovement which is in CharacterMotor.
I get nullReferenceException when i run this code and try to pick up the object.

function OnTriggerEnter(other:Collider)
{

 var fpc = other.gameObject;
 var fpcComponent = fpc.GetComponent("CharacterMotor");
 fpcComponent.CharacterMotorMovement.maxForwardSpeed = newSpeed;
 Destroy(gameObject);

}

2

function OnTriggerEnter(other:Collider) {
var fpcComponent:CharacterMotor = other.gameObject.GetComponent(“CharacterMotor”) as CharacterMotor;
fpcComponent.CharacterMotorMovement.maxForwardSpeed = newSpeed;
Destroy (gameObject, 0.0f);
}

Un-tested!

3

1- CharacterMotorMovement is the type, not the actual variable; the CharacterMotorMovement variable created in CharacterMotor.js is movement.

2- You can use other.GetComponent(…) directly.

3- GetComponent(“CharacterMotor”) returns type Component, and you need the type CharacterMotor to access the movement variable - pass CharacterMotor without quotes and GetComponent will return the correct type.

4- To avoid runtime errors case other object enters the trigger, check if fpcComponent isn’t null (what happens when the object doesn’t have a CharacterMotor script):

  // you can get a component using the 'other' collider directly:
  var fpcComponent = other.GetComponent(CharacterMotor); // use the type without quotes
  if (fpcComponent){ // check if fpcComponent isn't null
      fpcComponent.movement.maxForwardSpeed = newSpeed;
  }