I have two classes one that has a list and I would like to have an event that every time this list was changed this event was called.
public class Exemplo
{
List<string> lista = new List<string>();
//Quando esta lista foi alterada
}
public class Exemplo1
{
protected virtual void QuandoListaAlterada(EventArgs e)
{
MessageBox.Show("Lista Foi Alterada");
}
}
One way is to extend the List class by adding an event, like this:
using System;
using System.Collections.Generic;
namespace teste
{
class Program
{
class ListaComEventos<T> : List<T>
{
public event EventHandler OnAdicionar;
public void Adicionar(T item)
{
if (OnAdicionar != null)//verifica se evento foi especificado
{
OnAdicionar(this, null);
}
base.Add(item);
}
}
static void Main(string[] args)
{
ListaComEventos<int> minhaLista = new ListaComEventos<int>();
minhaLista.OnAdicionar += new EventHandler(EventoAdicionar);
minhaLista.Adicionar(1);
minhaLista.Adicionar(1);
minhaLista.Adicionar(1);
Console.ReadKey();
}
static void EventoAdicionar(object sender, EventArgs e)
{
Console.WriteLine("Um elemento foi adicionado");
}
}
}
Here is the code running on .netFiddle
There is a collection type in C # that notifies changes made to the list through events, at ObservableCollection .
With it, you can assign a method in the CollectionChanged event to receive change notifications in the list and also use the PropertyChanged event to receive notification of changes in the properties.
using System;
using System.Collections.ObjectModel;
namespace ObservableCollectionExample
{
class Program
{
static void Main(string[] args)
{
ObservableCollection<string> list = new ObservableCollection<string>();
list.CollectionChanged += List_CollectionChanged;
list.Add("Teste 1");
list.Add("Teste 2");
}
private static void List_CollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
{
Console.WriteLine("A lista foi alterada.");
}
}
}
See working at DotNetFiddle