String interpolation between if statements

Question

So i have this speech recognition code with a few commands that trigger animations in C# and Unity. So instead of having to activate each animation then deactivate it before switching to another animation I wanted to make it so that whatever animator is active it would automatically detect that, play the corresponding outro animation and go to the next animation all in one command. The solution I came up with is string interpellation.

The problem is I keep getting the error:

Object reference not set to an instance of an object.

In Unity pertaining to the line where (“{outro}”) is referenced and I’m not sure but maybe it’s because I’m trying to use string interpolation across 2 if statements?

P.S without the additional if statement this script works it still runs in Unity with the 2nd if statement but it doesn’t do what it’s supposed to.

if (word == “animator 2”)
{
    if (GameObject.Find(“animator 1”).activeSelf);
    {
        string outro = “animation”;
    }
    GameObject.Find(“animator 1”).GetComponent<Animator>
    ().SetBool(“{outro}”, true);
    GameObject.Find(“animator 2”).GetComponent<Animator>
    ().SetBool(“intro”, true);
}

So upon receiving many responses to this post I am able to narrow my problem down to one simple question.

Is it possible to reference a variable from an if statement?

Because I do need the if statement unless their is some other method that does the exact same thing. The only issue now is the variable “outro” is obviously not even a thing outside of the if statement. I believe if I could reference outro properly this code would work 100%

Answer 1

Maybe it is just the formatting here but check your " symbols .. they are strange.

• The reason your outro string isn't found is because you declare it within the if block ... it is not known outside of this scope. Declare the variable outside of the if block. You could/should even make it a const since it doesn't change anywhere between its declaration and usage.

• If you would use a string interpolation it has to start with a $ symbol

  SetBool($"{outro}", true);
  

  However in this case you pass only exactly one simple string value so there is absolutely no need to use string interpolation at all. Rather simply pass in the variable itself

  SetBool(outro, true);
  

• The NullReferenceExceptions comes either from your Find or GetComponent call.

  Since you are checking if the animator 1 object is activeSelf it seems pretty obvious that in some cases it might not be.

  In this case Find will return null. This is probably where the exception comes from mainly.

  This function only returns active GameObjects. If no GameObject with name can be found, null is returned. If name contains a '/' character, it traverses the hierarchy like a path name.

  Next it is also possible that the found object simply doesn't have an Animator attached so GetComponent returns null.

  Returns the component of Type type if the game object has one attached, null if it doesn't.

Best way to find out is debugging and do your stuff in single steps and check each retrieved reference for null.

private const string OUTRO = "animation";

// Personally in general as soon as you use strings that never change anyway I would recommend a const
private const string ANIMATOR_1 = "animator 1";
private const string ANIMATOR_2 = "animator 2";
private const string INTRO = "intro";
private const string ERROR_COMPONENT_NOT_FOUND = "The object {0} has no Animator Component!";
private const string ERROR_OBJECT_NOT_FOUND = "No object with name {0} was found! It Either doesn't exist or is not active in the hierarchy!";

...

    if (word == ANIMATOR_2)
    {
        // This is expensive! Do it only once or avoid it completely if possible!
        var animatorObj = GameObject.Find(ANIMATOR_1);

        // Not found?
        if(!animatorObj)
        {
            Debug.LogErrorFormat(this, ERROR_OBJECT_NOT_FOUND, ANIMATOR_1);
            return;
        }

        // You can completely skip the check for activeSelf!
        // If the object is not active it will never be found!

        // Also do this only once
        var animator = animatorObj.GetComponent<Animator>();

        // Component not found?
        if(!animator)
        {
            Debug.LogErrorFormat(this, ERROR_COMPONENT_NOT_FOUND, animatorObj.name);
            return;
        }

       // There is absolutely no sense of using string interpolation $""
       // If you pass in exactly one string value .. why not rather simply pass the variable itself directly? 
       animator.SetBool(OUTRO, true);
       animator.SetBool(INTRO, true);
    }