Access list storing custom class variables from another script

Question

My first script looks like this: using System.Collections; using System.Collections.Generic; using UnityEngine;

public class UpgradeManager : MonoBehaviour {

 public static List<Upgrades> UpgradesList = new List<Upgrades>();

 public class Upgrades
 {
     public string UpgradeName;
     public int MultiplierNumber;
     public double UpgradePrice;
     public int TargetGenerator;

     public Upgrades(string newName, int newNumber, double newPrice, int newGenerator)
     {
         UpgradeName = newName;
         MultiplierNumber = newNumber;
         UpgradePrice = newPrice;
         TargetGenerator = newGenerator;
     }

 }

 public Upgrades Upgrade1 = new Upgrades("2x infrastructure", 2, 100, 1);
 public Upgrades Upgrade2 = new Upgrades("3x Tax rate", 3, 150, 0);
 public Upgrades Upgrade3 = new Upgrades("4x infrastrucutre", 4, 200, 1);

 private void Start()
 {
     UpgradesList.Add(Upgrade1);
     UpgradesList.Add(Upgrade2);
     UpgradesList.Add(Upgrade3);
 }

}

And my second script tries to retrieve data from this script like this: using System.Collections; using System.Collections.Generic; using UnityEngine; using UnityEngine.UI;

public class UpgradeScript : MonoBehaviour { public string UpgradeName = UpgradeManager.UpgradesList[0].UpgradeName; public int MultiplierNumber = UpgradeManager.UpgradesList[0].MultiplierNumber; public double UpgradePrice = UpgradeManager.UpgradesList[0].UpgradePrice; public int TargetGenerator = UpgradeManager.UpgradesList[0].TargetGenerator;

 void Update()
 {
 }

}

And when I try to run my game it gives me this error: ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index

Somebody please help me thank you.

Answer 1

The problem is you are trying to access the list before any items have been added to it. In your first script, move the code in the Start function to the Awake function. Then in your second script, initialize your values in the Start function.

 public class UpgradeManager : MonoBehaviour {
 
     public static List<Upgrades> UpgradesList = new List<Upgrades> ();
     public class Upgrades {
         public string UpgradeName;
         public int MultiplierNumber;
         public double UpgradePrice;
         public int TargetGenerator;
         public Upgrades (string newName, int newNumber, double newPrice, int newGenerator) {
             UpgradeName = newName;
             MultiplierNumber = newNumber;
             UpgradePrice = newPrice;
             TargetGenerator = newGenerator;
         }
     }
     
     public Upgrades Upgrade1 = new Upgrades ("2x infrastructure", 2, 100, 1);
     public Upgrades Upgrade2 = new Upgrades ("3x Tax rate", 3, 150, 0);
     public Upgrades Upgrade3 = new Upgrades ("4x infrastrucutre", 4, 200, 1);
     
     private void Awake() {
         UpgradesList.Add (Upgrade1);
         UpgradesList.Add (Upgrade2);
         UpgradesList.Add (Upgrade3);
     }
 }

and

 public class UpgradeScript : MonoBehaviour {
     public string UpgradeName;
     public int MultiplierNumber;
     public double UpgradePrice;
     public int TargetGenerator;
 
     void Start () {
         UpgradeName = UpgradeManager.UpgradesList[0].UpgradeName;
         MultiplierNumber = UpgradeManager.UpgradesList[0].MultiplierNumber;
         UpgradePrice = UpgradeManager.UpgradesList[0].UpgradePrice;
         int TargetGenerator = UpgradeManager.UpgradesList[0].TargetGenerator;
     }
 
 }

Access list storing custom class variables from another script

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