c# item with the same key has already been added

Question

This code comes from a videogame,i need to add various items of this type,but when i change locations in a new script duped,there is an existing key with same parameter,how can i change key value for each one?Thank you so much,Here is the important code from script:

`

protected Dictionary<Point3D, Map> ListOfLocations = new Dictionary<Point3D, Map>()
        {
            { new Point3D(1185, 1838, 0), Map.Felucca },
            { new Point3D(1215, 1809, 0), Map.Felucca },
            { new Point3D(1215, 1839, 0), Map.Felucca },
            { new Point3D(1214, 1839, 0), Map.Trammel },
        };
public Point3D GetRandomLocation()
        {
            return ListOfLocations.ElementAt(Utility.Random(0, ListOfLocations.Count)).Key;
        }

`

Does this answer your question? [Argument Exception "Item with Same Key has already been added"](https://stackoverflow.com/questions/26516825/argument-exception-item-with-same-key-has-already-been-added) — George Kerwood, Sep 17 '22 at 08:14

Pradeep Kumar · Answer 1 · 2022-09-17T11:37:10.140

Cannot insert same key in dictionary So I have written sample code that will help you.

what I got from your question is that Location is key of dictionary that is type of Point3D

            Point3D location = your location;
            if (!ListOfLocations.ContainsKey(location))
            {
                // then change in dictionary for location
            }
            else
            {
                 Map map = ListOfLocations[location];
                ListOfLocations.Remove(location);
               // then change in dictionary for location as per your requirement
               //for Example ListOfLocations.Add(location, newmap);
                
            }

Algo :-

check key exist in dictionary(that use hashtable in background)

1.a if No then do needful.

1.b else remove existing key from dictionary then do needful.

score 0 · Answer 2 · answered Sep 17 '22 at 09:56

If the Point3D is an object, not a struct, then modifying it wont change its reference value, which is used as an actual key in the dictionary in this case. Easiest way of changing a key in this case would be to remove key value pair and add a newly created one (newly created key and same value will work). For only changing the value it would not be necessary.

c# item with the same key has already been added

2 Answers2