Question IndexOutOfRangeException

I made mistake and I deleted a wrong script and now when I made it again I get this error:

IndexOutOfRangeException: Index was outside the bounds of the array.
SpawnManager.SpawnRandomWall () (at Assets/Scripts/SpawnManager.cs:24)

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class SpawnManager : MonoBehaviour
6. {
7.     public GameObject[] wallPrefab;
8.    
9.  
10.     private float startDelay = 2.0f;
11.     private float spawnInterval = 1.5f;
12.    
13.  
14.     public void Start()
15.     {
16.        InvokeRepeating("SpawnRandomWall", startDelay, spawnInterval);
17.     }
18.     public void SpawnRandomWall()
19.     {
20.         int wallIndex = Random.Range(0, wallPrefab.Length);
21.         Vector2 spawnPos = new Vector2(10, 0);
22.  
23.  
24.         Instantiate(wallPrefab[wallIndex], spawnPos, wallPrefab[wallIndex].transform.rotation);
25.     }
26.  
27.  
28. }
29.  

(I know that the error is on line 24 but I dont know why because is the exact same script as the script that I deleted (I made a backup) and the game works as before, is just that error)

 

Here are some notes on IndexOutOfRangeException and ArgumentOutOfRangeException:

http://plbm.com/?p=236

Steps to success:
- find which collection it is and what line of code accesses it <--- critical first step!)
- find out why it has fewer items than you expect
- fix whatever logic is making the indexing value exceed the collection size
- remember that a collection with ZERO elements cannot be indexed at all: it is empty
- remember you might have more than one instance of this script in your scene/prefab
- remember the collection may be used in more than one location in the code
- remember that indices start at ZERO (0) and go to the count / length minus 1.

This means with three (3) elements, they are numbered 0, 1, and 2 only.

 

Your array of prefabs is empty. You need to add some prefabs to it in the inspector.

 

I added the prefabs in the inspector....Is not that. The game works as before, I just cant get rid of that error....It can be a bug from Unity?(Im using Unity 2021.3.15f1)

 

I solved the problem! Instead of making a separate script for spawning, I just put the code inside the GameManager script and now I dont get any error. But when I tried again to make a SpawnManager script and copy paste the exact same code for spawning I still get that error...but the same code inside GameManager script dont show any error. Is because I deleted the first SpawnManager script and I made another one after?

 

Nobody here knows.

Here is how you can find out.

Time to start debugging! Here is how you can begin your exciting new debugging adventures:

You must find a way to get the information you need in order to reason about what the problem is.

Once you understand what the problem is, you may begin to reason about a solution to the problem.

What is often happening in these cases is one of the following:

- the code you think is executing is not actually executing at all
- the code is executing far EARLIER or LATER than you think
- the code is executing far LESS OFTEN than you think
- the code is executing far MORE OFTEN than you think
- the code is executing on another GameObject than you think it is
- you're getting an error or warning and you haven't noticed it in the console window

To help gain more insight into your problem, I recommend liberally sprinkling

Debug.Log()

statements through your code to display information in realtime.

Doing this should help you answer these types of questions:

- is this code even running? which parts are running? how often does it run? what order does it run in?
- what are the names of the GameObjects or Components involved?
- what are the values of the variables involved? Are they initialized? Are the values reasonable?
- are you meeting ALL the requirements to receive callbacks such as triggers / colliders (review the documentation)

Knowing this information will help you reason about the behavior you are seeing.

You can also supply a second argument to Debug.Log() and when you click the message, it will highlight the object in scene, such as

Debug.Log("Problem!",this);

If your problem would benefit from in-scene or in-game visualization, Debug.DrawRay() or Debug.DrawLine() can help you visualize things like rays (used in raycasting) or distances.

You can also call Debug.Break() to pause the Editor when certain interesting pieces of code run, and then study the scene manually, looking for all the parts, where they are, what scripts are on them, etc.

You can also call GameObject.CreatePrimitive() to emplace debug-marker-ish objects in the scene at runtime.

You could also just display various important quantities in UI Text elements to watch them change as you play the game.

Visit Google for how to see console output from builds. If you are running a mobile device you can also view the console output. Google for how on your particular mobile target, such as this answer for iOS: https://forum.unity.com/threads/how-to-capturing-device-logs-on-ios.529920/ or this answer for Android: https://forum.unity.com/threads/how-to-capturing-device-logs-on-android.528680/

If you are working in VR, it might be useful to make your on onscreen log output, or integrate one from the asset store, so you can see what is happening as you operate your software.

Another useful approach is to temporarily strip out everything besides what is necessary to prove your issue. This can simplify and isolate compounding effects of other items in your scene or prefab.

Here's an example of putting in a laser-focused Debug.Log() and how that can save you a TON of time wallowing around speculating what might be going wrong:

https://forum.unity.com/threads/coroutine-missing-hint-and-error.1103197/#post-7100494

"When in doubt, print it out!(tm)" - Kurt Dekker (and many others)

Note: the

print()

function is an alias for Debug.Log() provided by the MonoBehaviour class.

 

It's not a Unity bug. You have another copy of this script in your scene, where the array is empty. It's what I said before.

 

Debug.Log is always here to help.

You could throw something like this into your script:

Code (CSharp):

1. private void Awake()
2. {
3.     Debug.Log("Wall Prefabs Count: " + wallPrefabs.Length, this);
4. }

So not only will you see how many game objects have this component attached, clicking on the log entry will also highlight the object.