Cant call my method on object from arraylist

Question

I'm calling getName() method from Achiv class on an ArrayList in printAchiv() method located in Achievements script and it throws an error.

Here is the error message that I get on the line Debug.Log("Achiv "+i+": "+ achivList[i].getName());:

Type object' does not contain a definition for getName' and no extension method getName' of type object' could be found (are you missing a using directive or an assembly reference?)

I'm just trying to access value of var "name" from obejct in collection.

Achiv class :

using UnityEngine;
using System.Collections;

public class Achiv: MonoBehaviour 
{

    public string name;

    public Achiv(string name) 
    {
        this.name = name;
    }

    public string getName() 
    {
        return name;
    }
}

---

Achievements script :

using UnityEngine;
using System.Collections;

public class Achievements: MonoBehaviour 
{

    public ArrayList achivList = new ArrayList();

    void Start() 
    {
        achivList.Add(
            new Achiv("First name", "Descirptionn", false));
            
        achivList.Add(
            new Achiv("Second name", "Descirptionnn", false));

        printAchiv();
    }

    void printAchiv() 
    {

        for (int i = 0; i <= achivList.Count - 1; i++)
            Debug.Log("Achiv " + i + ": " + achivList[i].getName());
    }
}

Answer 1

Use List<Achiv> instead of ArrayList. ArrayList is archaic, not type safe shouldn't be used anymore.

Indexer of ArrayList returns object that's why you get the error. Try the following.

public List<Achiv> achivList = new List<Achiv>();

Apart from this,

• Don't expose List publicly, prefer ReadOnlyCollection or IEnumerable.
• Prefer foreach over for unless there is a good reason.
• printAchiv doesn't follow proper naming convention, In c# we use "CamelCase", Rename it to PrintAchiv.
• get/set methods are for java style languages which doesn't supports properties. In c# we use properties instead. Create a property namely Name.

Answer 2

The problem is that the elements inside the ArrayList are stored as object. Thus achivList[i] returns an object, which does not provide the getName() method. Either you can add a cast:

            Debug.Log("Achiv "+i+": "+ (Achiv)achivList[i].getName());

or you can switch to a generic List:

using UnityEngine;
using System.Collections.Generic;

public class Achievements: MonoBehaviour {


    public  List<Achiv> achivList = new List<Achiv>();


    void Start () {

        achivList.Add (new Achiv("First name", "Descirptionn", false));
        achivList.Add (new Achiv("Second name", "Descirptionnn", false));


        printAchiv();

    }


    void printAchiv(){

        for (int i = 0; i <= achivList.Count - 1; i++)
        {

            Debug.Log("Achiv "+i+": "+ achivList[i].getName());
        }
    }   
}