Active Inventory null reference exception not fixed

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#1

The active inventory issue featured and fixed in this section of the 2D rpg combat course was not fixed for me and I am unsure why.

active inventory script below:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class ActiveInventory : MonoBehaviour
{
   private int activeSlotIndexNum = 0;
   private PlayerControls playerControls;

   private void Awake(){
        playerControls = new PlayerControls();
   }

   private void Start() {
        playerControls.Inventory.Keyboard.performed += ctx => ToggleActiveSlot((int)ctx.ReadValue<float>());
        ToggleActiveHighlight(0);
   }

   private void OnEnable() {
        playerControls.Enable();
   }

   private void ToggleActiveSlot(int numValue){
     ToggleActiveHighlight(numValue-1);
   }

   private void ToggleActiveHighlight(int indexNum){
     activeSlotIndexNum = indexNum;
     foreach (Transform inventorySlot in this.transform) {
        inventorySlot.GetChild(0).gameObject.SetActive(false);
     }

     this.transform.GetChild(indexNum).GetChild(0).gameObject.SetActive(true);
   this.transform.GetChild(indexNum).GetChild(0).gameObject.SetActive(true);
    ChangeActiveWeapon();
   }

   private void ChangeActiveWeapon (){
    if (ActiveWeapon.Instance.CurrentActiveWeapon != null){
        Destroy(ActiveWeapon.Instance.CurrentActiveWeapon.gameObject);
    }
     
     Transform childTransform = transform.GetChild(activeSlotIndexNum);
    InventorySlot inventorySlot = childTransform.GetComponent<InventorySlot>();
    WeaponInfo weaponInfo = inventorySlot.GetWeaponInfo();
    GameObject weaponToSpawn = weaponInfo.weaponPrefab;
   
    if (weaponInfo==null){
        ActiveWeapon.Instance.WeaponNull();
        return;
    }
   
   GameObject newWeapon = Instantiate(weaponToSpawn, ActiveWeapon.Instance.transform.position, Quaternion.identity);
   ActiveWeapon.Instance.transform.rotation = Quaternion.Euler(0,0,0);
   newWeapon.transform.parent = ActiveWeapon.Instance.transform;
   ActiveWeapon.Instance.NewWeapon(newWeapon.GetComponent<MonoBehaviour>());
}

}

active inventory issue 1

#2

There’s a LOT in ChangeActiveWeapon, and it’s next to impossible to determine which actual statement is the culprit in this…

Double click on the error, and a specific line in ChangeActiveWeapon will be selected in VS Code. That should help narrow things down, if you can mark the specific line.

I’ve attached a guide to pasting in code… simply pasting it in as text with no modifiers tends to make it difficult to format later.

1 Like
#3

Hi thanks for the guide. I dont really understand it though, is there a video tutorial available to show me what’s required??

#4

code issues
code issues712×338 19.7 KB

The issue says line 53.

#5

Ok, that makes sense. What’s happening is that you’re using weaponInfo before it has been null checked. Move the line

GameObject weaponToSpawn = weaponInfo.weaponPrefab;

to after the null check clause

    if (weaponInfo==null){
        ActiveWeapon.Instance.WeaponNull();
        return;
    }
   GameObject weaponToSpawn = weaponInfo.weaponPrefab;
   GameObject newWeapon = Instantiate(weaponToSpawn, ActiveWeapon.Instance.transform.position, Quaternion.identity);

Heres’ the skinny on code formatting:
Next to the 1 key on your keyboard is a backwards quote symbol. It looks like this `, and not ‘.
On it’s own line before pasting in a block of code, type that symbol three times, it will look like this
```
not like
‘’’
Then you can paste or type in your code, for example
```

public void MyMethod()
{
    DoSomething();
}

```
becomes

public void MyMethod();
{
    DoSomething();
}
1 Like
#6

Thanks dude.

#7

Cheers for the advice on moving the code. So moving it the exact way you said caused another issues where it says I am calling the code before its defined. So I tried this (but I am not advanced enough to know if this will cause some other issue down the line or not:

Transform childTransform = transform.GetChild(activeSlotIndexNum);
     InventorySlot inventorySlot = childTransform.GetComponent<InventorySlot>();
     WeaponInfo weaponInfo = inventorySlot.GetWeaponInfo();
    if (weaponInfo==null){
        ActiveWeapon.Instance.WeaponNull();
        return;
    }
     
    GameObject weaponToSpawn = weaponInfo.weaponPrefab;
#8

Good job! No, this code should work perfectly.

#9

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