I’ve always following the tutorial video all the time, but this time I got this problem “NullReferenceException Object reference not set to an instance of an object”
and the error line is
int targetCountAtGridPosition = unit.GetShootAction().GetTargetCountAtPosition(gridPosition);
has been keep working on it for 3days…
I’m not a good code writer…
That line of code is calling this public method in the Unit script:
public ShootAction GetShootAction()
{
return shootAction;
}
If your Enemy Units don’t have a ShootAction script attached to them, it will give you a null reference error.
Except that the error would then be Unit.ShootAction instead of MoveAction.GetEnemyAIAction.
Can you paste in your complete MoveAction script?
i’m 100% following the code of MoveAction from Gitlab…
using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class MoveAction : BaseAction
{
public event EventHandler OnStartMoving;
public event EventHandler OnStopMoving;
[SerializeField] private int maxMoveDistance = 4;
private Vector3 targetPosition;
protected override void Awake()
{
base.Awake();
targetPosition = transform.position;
}
private void Update()
{
if (!isActive)
{
return;
}
Vector3 moveDirection = (targetPosition - transform.position).normalized;
float stoppingDistance = .1f;
if (Vector3.Distance(transform.position, targetPosition) > stoppingDistance)
{
float moveSpeed = 4f;
transform.position += moveDirection * moveSpeed * Time.deltaTime;
}
else
{
OnStopMoving?.Invoke(this, EventArgs.Empty);
ActionComplete();
}
float rotateSpeed = 10f;
transform.forward = Vector3.Lerp(transform.forward, moveDirection, Time.deltaTime * rotateSpeed);
}
public override void TakeAction(GridPosition gridPosition, Action onActionComplete)
{
this.targetPosition = LevelGrid.Instance.GetWorldPosition(gridPosition);
OnStartMoving?.Invoke(this, EventArgs.Empty);
ActionStart(onActionComplete);
}
public override List<GridPosition> GetValidActionGridPositionList()
{
List<GridPosition> validGridPositionList = new List<GridPosition>();
GridPosition unitGridPosition = unit.GetGridPosition();
for (int x = -maxMoveDistance; x <= maxMoveDistance; x++)
{
for (int z = -maxMoveDistance; z <= maxMoveDistance; z++)
{
GridPosition offsetGridPosition = new GridPosition(x, z);
GridPosition testGridPosition = unitGridPosition + offsetGridPosition;
if (!LevelGrid.Instance.IsValidGridPosition(testGridPosition))
{
continue;
}
if (unitGridPosition == testGridPosition)
{
// Same Grid Position where the unit is already at
continue;
}
if (LevelGrid.Instance.HasAnyUnitOnGridPosition(testGridPosition))
{
// Grid Position already occupied with another Unit
continue;
}
validGridPositionList.Add(testGridPosition);
}
}
return validGridPositionList;
}
public override string GetActionName()
{
return "Move";
}
public override EnemyAIAction GetEnemyAIAction(GridPosition gridPosition)
{
int targetCountAtGridPosition = unit.GetShootAction().GetTargetCountAtPosition(gridPosition);
return new EnemyAIAction
{
gridPosition = gridPosition,
actionValue = targetCountAtGridPosition * 10,
};
}
}
Let’s add a couple Debugs to be sure of what’s null and what’s not:
if(!unit) { Debug.LogError("{gameObject.name} MoveAction has no reference to Unit");}
if(!unit.GetShootAction()) {Debug.LogError($"{gameObject.name} has no ShootAction Attached");}
int targetCountAtGridPosition = unit.GetShootAction().GetTargetCountAtPosition();
//rest of method
Thank you so much!!! i found that it was the ShootAction was not attached…
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