未从列表中删除项目

Question

Item is not being remove from list

here is my code:

public interface IEmpConnection
{
    int SegId { get; set; }
}

public class EmpConnection : IEmpConnection
{

    private int segid;
    public int SegId
    {
        get
        {
            return segid;
        }
        set
        {
            segid = value;
        }
    }
}

public class CustomerConnection : EmpConnection, ICustomerConnection
{

    private int _id;

    public int Id
    {
        get
        {
            return _id;
        }
        set
        {
            _id = value;
        }
    }
}

public interface ICustomerConnection
{
    int Id { get; set; }


}

public class CustConn : CustomerConnection
{
    private ObservableCollection<CustomerConnection> _airSeg;

    public CustConn()
    {
        _airSeg = new System.Collections.ObjectModel.ObservableCollection<CustomerConnection>();
        _airSeg.Add(new AirSegmentConnection { Id = 1, SegId = 2 });
        _airSeg.Add(new AirSegmentConnection { Id = 1, SegId = 3 });
    }

    private bool isDeleted;

    public bool IsDeleted
    {
        get { return isDeleted; }
        set { isDeleted = value; }
    }

    private List<IEmpConnection> _connection;
    public List<IEmpConnection> Connections
    {
        get
        {
            var s = new AirSegmentConnection();
            var k = s as ISegmentConnection;

            if (IsDeleted)
            {
                _airSeg.RemoveAt(1);
            }

            return _connection = _airSeg.ToList().Cast<ISegmentConnection>().ToList();
            //return _airSeg.ToList().Cast<ISegmentConnection>().ToList();
        }

        set
        {
            _connection = value;
            //_airSeg = new System.Collections.ObjectModel.ObservableCollection<ISegmentConnection>(value.ToList()) ;
        }
    }

    private ObservableCollection<CustomerConnection> airConnection;

    public ObservableCollection<CustomerConnection> AirConnection
    {
        get { return _airSeg; }
        set { _airSeg = value; }
    }
}

on main

button click item is not being removed. please suggest me where i am doing wrong.

CustConn a = new CustConn();
if (a.Connections.Count > 0)
{
    a.Connections = new List<IEmpConnection>();
    a.Connections.RemoveAt(1);// this item is not being removed.
}

please suggest i am doing worng in this code.

Thanks Amit

Answer 1

You're creating a new, empty list and then trying to remove an element at position 1. In fact you've just overwritten your original list.

if (a.Connections.Count > 0)
{
    /// REMOVE THIS LINE a.Connections = new List<IEmpConnection>();
    a.Connections.RemoveAt(1);// this item is not being removed.
}

The line I've commented out it creating a new list and overwriting a.Connections immediately before you try to remove the item. This is what's causing the code to fail.

Answer 2

It seems that you are replacing the list of connections before you remove the connection.

Since you have this marked as WPF, I'm going to assume that at some point you were able to remove the item from the List, but it still appeared on the screen. Try this:

if (a.Connections.Count > 0)
{
     var newList = new List<IEmpConnection>(a.Connections);
     a.Connections.RemoveAt(1);
     a.Connections = newList;
} 

Alternatively, you may be able to use an ObservableCollection<IEmpConnection> . This is a special collection that raises events when the collection changes. Then you would simple remove the object, and the screen would update.