FindObjectsOfType vs List.Contains Performance?

Questions & Answers
1

Hello.

I have a very quick question I was wondering which one would have least spike in the performance. I have an object which has to locate another object depending on a specific ID. Here I uses FindObjectsOfType every time, it’s a one time event called a few times each minute. Then I thought I could create a list and when it finds objects of that type throw them into the list and later use list.Contain() and if list doesn’t contain the object use FindObjectsOfType again and throw the new objects into the list. Would this improve performance or wouldn’t it actually matter?

Kind regards.

2

There is something exactly for this, a dictionary.
It can use the TryGetValue call which is a very fast call to retrieve / cache already found objects by a unique key.
Basically you give a key and a value to a dictionary, where you can then retrieve the value by its key.
Here’s an example of pseudo code where I use an int as key and gameobject as value:

Dictionary<int, GameObject> cachedObjects = new Dictionary<int, GameObject>();

GameObject connectedObject; //our holder for when we do find the object
// Locate the other gameobject by specific id
if (cachedObjects.TryGetValue(id, out connectedObject)) {
// If we already have some object by this specific ID then do w/e
// our gameobject will be inside the connectedObject variable
}
else 
{
// Do w/e expensive call to retrieve the object you require
//add the retrieved object by the specific id as key so we can get it fast nexttime
//without having to do the expensive call to retrieve it again
cachedObjects.Add(id, retrievedgameobject); 
}

Do note a dictionary can only have UNIQUE keys.
If one key can store more objects then your value will have to be a list of gameobjects like so:

Dictionary<int, List<GameObject>> cachedObjects = new Dictionary<int, List<GameObject>>();

List<GameObject> connectedObjects;
if (cachedObjects.TryGetValue(id, out connectedObjects)) {
    // we already have a list of objects so we can just add to it or use them
    connectObjects.Add(someOtherObject);
}
else 
{
// we don't have a list yet
var listdata = new List<GameObject>();
listdata.Add(someitem);
// do some expensive calls and add items to the list, then add the list with key to dictionary
cachedObjects.Add(id, listdata); 
}