Why is the object not initialized?

Question

C++ / C#

There is a parent class that has a monsterObj field

public abstract class MonsterBehaviorBase : MonoBehaviour
{
    protected IMonster monsterObj;
    protected Transform tr;
    protected float speed;
    // Start is called before the first frame update
    public virtual void Start()
    {
        tr = GetComponent<Transform>();
    }

    // Update is called once per frame
    public virtual void Update()
    {
        Move();
    }
    public virtual void Move()
    {

    }
    public virtual void OnCollisionEnter(Collision collision)
    {
        if (collision.collider.CompareTag("Player"))
        {
            monsterObj.Attack();
        }
        else
        {
            ChangeState();
        }
    }
    public virtual void ChangeState()
    {

    }
}

Child class in which monsterObj is initialized

public class AttackingMonsterBehaviour : MonsterBehaviorBase
{
    private MovingSystem moveSys;
    private Transform movingSysObj;
    // Start is called before the first frame update
    public override void Start()
    {
        speed = 4f;
        monsterObj = new AttakingMonster(tr.gameObject, Player.instance, Random.Range(10, 20));
        movingSysObj = tr.parent;
        InitScriptMovingSys Sys = movingSysObj.GetComponent<InitScriptMovingSys>();
        moveSys = Sys.moveSys;
    }

Inheritance system for the AttakingMonster class:

public interface IMonster
{
    void SetAttackClass(IAttack _class);
    void Attack();
}
public abstract class MonsterBase : IMonster
{
    protected Animator anim;
    protected float attackharm;
    public GameObject monster;
    protected Player player;
    protected IAttack attackclass;
    public float speed { get; set; }
    public MonsterBase(GameObject _monster, Player _player, float _attackharm)
    {
        monster = _monster;
        anim = monster.GetComponent<Animator>();
        player = _player;
        attackharm = _attackharm;
        speed = 3;
    }
    public void SetAttackClass(IAttack _class)
    {
        attackclass = _class;
    }
    public void Attack()
    {
        player.health -= attackharm;
        attackclass.Attack(anim);
    }
}
public class AttakingMonster : MonsterBase
{
    public AttakingMonster(GameObject _monster, Player _player, float _attackharm) : base(_monster, _player, _attackharm)
    {
        monster = _monster;
        anim = monster.GetComponent<Animator>();
        player = _player;
        attackharm = _attackharm;
        SetAttackClass(new FighterAttack());
    }
}

As a result, monsterObj is always null. When debugging, the program simply stopped at the line where the object was created. Why is that? thanks for the help

Answer 1

Because you have at the moment

monsterObj = new AttakingMonster(tr.gameObject, Player.instance, Random.Range(10, 20));

tr null. In general, you always have it null, because you do not call the base methodStart