How to create an array of list of class objects in C#

Question

My C# class is as follows

public class SeatPlans
{
    public int Id { get; set; }
    public string seat_id { get; set; }
    public string seat_no { get; set; }
    public int layout_id { get; set; }
}

I have created a list of class object as follows

List<SeatPlans> allUser = new List<SeatPlans>();

but what I need is an array of lists so that I can access the data of several objects like allUser[0], allUser[1], allUser[2]

My controller code is as follows

public JsonResult getdata(int seat_plane_id)
{
    int lid = seat_plane_id;
    layoutsController L = new layoutsController();
    JsonResult result = L.getlayouts(lid);

    List<layouts> L1 = (List<layouts>)result.Data;
    List<List<SeatPlans>> allUser = new List<List<SeatPlans>>();

    for (int i = 0; i < L1.Count; i++)
    {
        String lid1 = L1[i].ticket_no_start;
        lid = Int32.Parse(lid1);
        allUser[i] = db.SEATPLAN.Where(d => d.layout_id == lid).ToList();
    }

    var v = new { allUser = allUser[0], allUser1 = allUser[1] };

    return Json(v, JsonRequestBehavior.AllowGet);
}

I'm getting

System.ArgumentOutOfRangeException exception

at

allUser[i] = db.SEATPLAN.Where(d => d.layout_id == lid).ToList();

You can still access the list item by index using allUser[0]. So getting the Id would be allUser[0].Id — Tah
– Tah, Commented May 14, 2016 at 7:26
allUser[0] contain the value of Id right?,but actualy i nee a separate list of classes in allUser[0],allUser[1],allUser[2] — rakshith
– rakshith, Commented May 14, 2016 at 7:29
i need something like this --- allUser[0] = db.SEATPLAN.Where(d => d.layout_id == lid).ToList(); allUser[1] = db.SEATPLAN.Where(d => d.layout_id == lid).ToList(); — rakshith
– rakshith, Commented May 14, 2016 at 7:43
ToList() returns a list. Trying to set to allUser[0] doesn't make sense unless you really want List<List<SeatPlans>>. You may need to use a GroupBy to take the List<SeatPlans> and break into groups so you would have a List<List<SeatPlans>> — jdweng
– jdweng, Commented May 14, 2016 at 7:48

Roman · Accepted Answer · 2016-05-14 08:02:11Z

2

To have an array of lists you can simply declare it:

List<SeatPlans>[] allUsers = new List<SetPlans>[size];

then you can get specific list by index:

allUsers[1] = new List<SetPlans>();

to get specific element of specific list:

SeatPlans specificSeatPlans = allUsers[1][2];

answered May 14, 2016 at 8:02

Roman

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Comments

Amit Hasan · Accepted Answer · 2016-05-14 07:37:19Z

1

you can use allUser[0],allUser[1],allUser[2] with List as well. allUser[0] gets the first SeatPlan object then you can access public members from that.

SeatPlan sp = allUser[0];
Console.Writeline(sp.Id);

will print out the first SeatPlan object's Id.

answered May 14, 2016 at 7:37

Amit Hasan

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3 Comments

rakshith Over a year ago

if i use the allUser[0] instead allUser it shows error(red marks)

Amit Hasan Over a year ago

@rakshi can you post your code where you are trying to use it.

rakshith Over a year ago

sir i have posted my controller

Tah · Accepted Answer · 2016-05-14 07:48:24Z

1

If you need an 2d array of objects you can create it like this:

List<List<SeatPlan>> allUser = new List<List<SeatPlan>>();

allUser.Add(db.SEATPLAN.Where(d => d.layout_id == lid).ToList());

note, you need to use the Add method to push a new object onto the list.

Accessing the individual objects can then be done via allUser[0][0], getting the Id for example would be allUser[0][0].Id

answered May 14, 2016 at 7:48

Tah

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2 Comments

rakshith Over a year ago

i am getting System.ArgumentOutOfRangeException from the point--- allUser[0] = db.SEATPLAN.Where(d => d.layout_id == lid).ToList();

Tah Over a year ago

You can't initialize a list that way. The constructor creates a 0 size List so allUser[0] doesn't exist yet. You have you use the Add method like in my answer.

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