Problem with arrays (inventory system) array not declared, will remain null or something like this

Questions & Answers
1

(sorry for everything lowercase, the shift on my keyboard is kinda stuck(u know how hard its to script that way?))

lately i decided to implement simple inventory system in my game. i created a simple image in paint.net that resembles thing i wanted to have. then i applied it to canvas. for every slot in this inventory i made a raw image with collider, and a counter thats a child of the image. works fine so far. then i made a script for it like this(not done yet)

using UnityEngine;
using System.Collections;

public class inwentarz : MonoBehaviour {

public GameObject eq; // whole inventory object
public bool czyEqWidoczne = false;
public bool czyMyszWolna = false;
public Texture[] itemyTeksturki; // item textures
private Texture[] itemyWEqtekstury; //textures of items that are in inventory now
private GameObject[] ObiektIkonyItemu; // array with image objects
private int[] itemyWequ; // the inventory itself
private string TerazPrzypisuje; //so that you can assign textures to arrrays
// ITEM & TEXTURE ids 0-nic 1-lom 2-pistolet 3-aks74u 4-jagody 5-kokosy 6-banany 7-magazynkiMakarow 8-magazynkiAKS74u 9-LeczniczeLiscie 
	void Start(){
		for(int i = 0; i < 20; i++)
		{
		TerazPrzypisuje = "Item (" + i.ToString() + ")"; 
			ObiektIkonyItemu *= GameObject.Find("Canvas/Inwentarz/" + TerazPrzypisuje);*

itemyWEqtekstury = ObiektIkonyItemu*.GetComponent().material.mainTexture;*
_ itemyWequ = 0;
* }
//Debug Items*
* itemyWequ[1] = 4;
itemyWequ[3] = 9;
}
void FixedUpdate () {
//Cursor.visible = true;
if(Input.GetKeyDown(KeyCode.Tab))
{
switch(czyEqWidoczne)
{
case false:
czyEqWidoczne = true;
eq.SetActive(true);
czyMyszWolna = true;
break;
case true:
czyEqWidoczne = false;
eq.SetActive(false);
czyMyszWolna = false;
break;
}
}
switch(czyMyszWolna)
{
case false:
Cursor.visible = false;
Cursor.lockState = CursorLockMode.Locked;
break;
case true:
Cursor.visible = true;
Cursor.lockState = CursorLockMode.None;
break;
}
for(int i = 0; i < 20; i++)
{
if(itemyWequ != 0)
{_
itemyWEqtekstury _= itemyTeksturki;
}
}
}
}
the game compiles and runs, but the debug items does not show in the inventory screen and some weird errors appear
NullReferenceException: Object reference not set to an instance of an object
(wrapper stelemref) object:stelemref (object,intptr,object)*
and i dont want to use pre-made inventory systems, because i know i wont learn anything that way. cheers!_

2

I`m assuming your error points to line 19? Its because you have not initialized the array with a length.
Theres two things you can do judging by your for loop using 20 I assume that is a hard coded inventory limit?
Either 1)

private Texture[] itemyWEqtekstury = new Texture[20];
private GameObject[] ObiektIkonyItemu = new GameObject[20];

or 2) make these arrays public and drag the objects onto the inspector.

3

I dont know how but i got it to working.And i deleted some unnecessary variables. this might make my script work slower, but hey, nobody pays me for making good optimized scripts ;p
Here it is:

using UnityEngine;
using System.Collections;
using UnityEngine.UI;
public class inwentarz : MonoBehaviour {

public GameObject eq; // caly obiekt inventory
public bool czyEqWidoczne = false;
public bool czyMyszWolna = false;
public Texture[] itemyTeksturki; // Tekstury itemow ktore ustawiasz w inspektorze, by mogly sie pokazac w eq
public GameObject[] ObiektIkonyItemu = new GameObject[20]; // by mozna bylo dostac sie do licznikow itemow
private int[] itemyWequ = new int[20]; // wlasciwe eq na podstawie ktorego beda wykonywane inne akcje
// 0-nic 1-lom 2-pistolet 3-aks74u 4-jagody 5-kokosy 6-banany 7-magazynkiMakarow 8-magazynkiAKS74u 9-LeczniczeLiscie 
	void Start(){
		for(int i = 0; i < 20; i++)
		{
			itemyWequ *= 0;*

  •  }*

  •  //Debug Itemy*

  •  itemyWequ[0] = 4;*

  •  itemyWequ[1] = 9;*

  •  itemyWequ[2] = 3;*
  • }*
  • void FixedUpdate () {*
  • //Cursor.visible = true;*
  • if(Input.GetKeyDown(KeyCode.Tab))*
  • {*
  •  switch(czyEqWidoczne)*

  •  {*

  •  	case false:*

  •  		czyEqWidoczne = true;*

  •  		eq.SetActive(true);*

  •  		czyMyszWolna = true;*

  •  		break;*

  •  	case true:*

  •  		czyEqWidoczne = false;*

  •  		eq.SetActive(false);*

  •  		czyMyszWolna = false;*

  •  		break;*

  •  }*
  • }*
  • switch(czyMyszWolna)*
  • {*
  •  case false:*

  •  	Cursor.visible = false;*

  •  	Cursor.lockState = CursorLockMode.Locked;*

  •  	break;*

  •  case true:*

  •  	Cursor.visible = true;*

  •  	Cursor.lockState = CursorLockMode.None;*

  •  	break;*
  • }*
  • for(int i = 0; i < 20; i++)*
  • {*
    _ if(itemyWequ != 0)_
    * {*
    _ Debug.Log("Wykryto nowy item w inventory! jego id to " + itemyWequ*.ToString() + "natomiast slot to "+i.ToString());
    ObiektIkonyItemu.GetComponent().texture = itemyTeksturki[itemyWequ-1];
    }
    }
    }
    }
    Honestly i had more luck doing this that i thinked it out myself. Especially this line
    ObiektIkonyItemu.GetComponent().texture = itemyTeksturki[itemyWequ-1];*
    was rather a desperate experiment than something thinked out. Anyways,thanks for help.And i need to get myself new keyboard._