Serialization Problem

I'm trying to save scriptable objects in my game.Help!
PlayerSettings.cs

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using System.Runtime.Serialization;
4. using UnityEngine;
5. [CreateAssetMenu(menuName = "PlayerSettings")]
6.  
7. public class PlayerSettings : ScriptableObject
8. {
9.     public List<Tool> tools;
10.     public List<Sword> swords;
11.     public Tool selectedTool;
12.     public Sword selectedSword;
13.     public float cash;
14.     public float multiplier;
15.     public float workers;
16. }
17.  

Tool.cs

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4. [CreateAssetMenu(menuName = "Tool")]
5. public class Tool : ScriptableObject
6. {
7.     public float strength;
8.     public float cost;
9. }
10.  

Sword.cs

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4. [CreateAssetMenu(menuName = "Sword")]
5. public class Sword : ScriptableObject
6. {
7.     public float damage;
8.     public float cost;
9. }
10.  

 

Lists aren't serializable; try using arrays instead

 

Thanks!