ClassList.cs

using System;
using System.Linq;
using UnityEditor;
using UnityEngine;
using UnityEngine.UIElements;

namespace MultiplayerARPG
{
    public class ClassList : EditorWindow
    {
        static string searchTerm = "t:PlayerCharacter"; // <-- A search filter to find each PlayerCharacter object in the project
        private PlayerCharacter[] objectList;
        private VisualElement root;

        [MenuItem("Tools/Class List")]
        private static void ShowWindow()
        {
            var window = GetWindow<ClassList>();
            window.titleContent = new GUIContent("Class List");
            window.Show();
        }

        private void Awake()
        {
            root = rootVisualElement;
        }

        private void OnEnable()
        {
            var scroller = new ScrollView {style = {paddingLeft = 10, paddingRight = 10, paddingTop = 5}};

            objectList = LoadData(); // <-- Loads the data from disk
            foreach (var playerCharacter in objectList)
            {
                scroller.Add(new Label($"{playerCharacter.title} : {playerCharacter.ClassID.ToString()}"));
            }    // For each playerCharacter that was loaded from disk, create a label and add the title and classid,
                 // then add it to the editor windows ScrollView object.

            root.Add(scroller);
        }
        
        
        PlayerCharacter[] LoadData()
        {                                        // --- Uses the search filter to locate all PlayerCharacter Scriptable objects
            var objects = AssetDatabase.FindAssets(searchTerm)    
                .Select(guid => AssetDatabase.LoadAssetAtPath<PlayerCharacter>(AssetDatabase.GUIDToAssetPath(guid))).ToArray(); // <== Returns them as an array  
            //                                             |^ -- Uses the found PlayerCharacter ScriptableObject results and loads each one from disk

            foreach (var item in objects)
            {
                Debug.Log($"Found: {item.name}");
            }

            return objects;
        }
    }
}