Issue with Vector 3 Array List (solved)

So, I'm making a very basic tile based generation system with what is probably an awful method to do so. I've just come from JS so this is supposed to be a pretty simple learning experience but I can't get past line 37.

The error is:
"Cannot implicitly convert type 'object' to 'UnityEngine.Vector3'. An explicit conversion exists (are you missing a cast?)"

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class SceneGenerator : MonoBehaviour {
5.     public GameObject tCross;
6.     public GameObject straight;
7.     public GameObject corner;
8.     public ArrayList PossiblePositions = new ArrayList();
9.     public ArrayList PossibleRotations = new ArrayList();
10.     public string lastPlaced;
11.     private GameObject lastPlacedObject;
12.     private GameObject block;
13.     private int blockSelector;
14.     private Vector3 placeholder = new Vector3(0, 0, 0);
15.     // Use this for initialization
16.     void Start () {
17.         firstGen();
18.     }
19.    
20.     // Update is called once per frame
21.     void Update () {
22.    
23.     }
24.  
25.     void firstGen()
26.     {
27.        block = Instantiate(tCross, new Vector3(0, 0, 0), Quaternion.Euler(new Vector3(-90,0,0))) as GameObject;
28.        lastPlaced = "tCross";
29.        findAvailableLocations();
30.     }
31.    
32.     void addNewBlock()
33.     {
34.         blockSelector = Random.Range(1, 3);
35.         if (blockSelector != 0)
36.         {
37.             placeholder = PossiblePositions[Random.Range(0, PossiblePositions.Count)];
38.             Instantiate(tCross, placeholder, Quaternion.Euler(-90, 0, 0));
39.         }
40.  
41.     }
42.    
43.     void findAvailableLocations()
44.     {
45.         if (lastPlaced == "tCross")
46.         {
47.             PossiblePositions.Add(new Vector3(block.transform.position.x + 3.5f, 0f, block.transform.position.z));
48.             PossiblePositions.Add(new Vector3(block.transform.position.x - 3.5f, 0f, block.transform.position.z));
49.             PossiblePositions.Add(new Vector3(block.transform.position.x, 0f, block.transform.position.z + 3.5f));
50.             PossiblePositions.Add(new Vector3(block.transform.position.x, 0f, block.transform.position.z - 3.5f));
51.             Invoke("addNewBlock", 3);
52.  
53.         }
54.     }
55.    
56.     void printAvailablePositions()
57.     {
58.         for (int x=0; x < PossiblePositions.Count; x++)
59.         {
60.  
61.             print(PossiblePositions[x]);
62.         }
63.     }
64. }
65.  

 

You need to explicit what type of variable its when you in some kind of list ( like arraylist ).
You can do this

Code (CSharp):

1. placeholder = PossiblePositions[Random.Range(0, PossiblePositions.Count)] as Vector3;

or

Code (CSharp):

1. placeholder = (Vector3) PossiblePositions[Random.Range(0, PossiblePositions.Count)];

 

You really, really don't want to use an array list. Consider a generic List instead.