[英]Sorting ObservableCollection<> manually
我在班级里遵循ObservableCollection
,我正在Windows phone 7
应用程序中使用该Collection将数据绑定到listbox
public ObservableCollection<CustomClass> myList = new ObservableCollection<CustomClass>();
public class CustomClass
{
public string Id { get; set; }
public string Name { get; set; }
public string EventName { get; set; }
public string EventDate get
{
return EventDate;
}
set
{
if (value != null)
{
DateTime eventDate = DateTime.Parse(value);
int today = DateTime.Now.Day;
if (eventDate.Day <= today + 1 & eventDate.Day >= today - 2)
{
if (eventDate.Day == today)
EventDate = "Today";
else if (eventDate.Day == (today + 1))
EventDate = "Tomorrow";
else if (eventDate.Day == (today - 1))
EventDate = "Yesterday";
else if (eventDate.Day >= (today - 2))
EventDate = "Just Passed";
}
else
{
EventDate = value;
}
}
}
}
现在我想根据EventDate
的数据对myList
进行排序
在所有情况下,EventDate中的数据均为以下之一
自定义收藏只能按上述顺序排序
我从不同来源获取数据,因此在将数据绑定到集合中时无法进行排序
可能吗??
由于您的CustomClass没有实现INotifyPropertyChange,因此我假设您只需在插入时排序(添加到集合时)。 因此,恕我直言,最容易做的事情(类似于RandolfRincón-Fadul的解决方案)是子类化,然后重写Add方法。
public class ComparingObservableCollection<T> : ObservableCollection<T>
where T : IComparable<T>
{
protected override void InsertItem(int index, T item)
{
int i = 0;
bool found = false;
for (i = 0; i < Items.Count; i++)
{
if (item.CompareTo(Items[i]) < 0) {
found = true;
break;
}
}
if (!found) i = Count;
base.InsertItem(i, item);
}
}
然后,您要做的就是在CustomClass上实现IComparable<CustomClass>
,如下所示:
public class CustomClass : IComparable<CustomClass>
{
public string Id { get; set; }
public string Name { get; set; }
public string EventName { get; set; }
public string EventDate { get
{
return EventDate;
}
set
{
if (value != null)
{
DateTime eventDate = DateTime.Parse(value);
int today = DateTime.Now.Day;
if (eventDate.Day <= today + 1 & eventDate.Day >= today - 2)
{
if (eventDate.Day == today)
EventDate = "Today";
else if (eventDate.Day == (today + 1))
EventDate = "Tomorrow";
else if (eventDate.Day == (today - 1))
EventDate = "Yesterday";
else if (eventDate.Day >= (today - 2))
EventDate = "Just Passed";
}
else
{
EventDate = value;
}
}
}
private int Order { get {
switch(EventDate) {
case "Just Passed": return 1;
case "Yesterday": return 2;
case "Tomorrow": return 3;
case "Today": return 4;
default: return 5;
}
}
}
public int CompareTo(CustomClass other) {
return this.Order.CompareTo(other.Order);
}
}
您可以始终子类化:
/// <summary>
/// Represents a dynamic data collection that provides notifications when items get added, removed, or when the whole list is refreshed and allows sorting.
/// </summary>
/// <typeparam name="T">The type of elements in the collection.</typeparam>
public class SortableObservableCollection<T> : ObservableCollection<T>
{
/// <summary>
/// Sorts the items of the collection in ascending order according to a key.
/// </summary>
/// <typeparam name="TKey">The type of the key returned by <paramref name="keySelector"/>.</typeparam>
/// <param name="keySelector">A function to extract a key from an item.</param>
public void Sort<TKey>(Func<T, TKey> keySelector)
{
InternalSort(Items.OrderBy(keySelector));
}
/// <summary>
/// Sorts the items of the collection in ascending order according to a key.
/// </summary>
/// <typeparam name="TKey">The type of the key returned by <paramref name="keySelector"/>.</typeparam>
/// <param name="keySelector">A function to extract a key from an item.</param>
/// <param name="comparer">An <see cref="IComparer{T}"/> to compare keys.</param>
public void Sort<TKey>(Func<T, TKey> keySelector, IComparer<TKey> comparer)
{
InternalSort(Items.OrderBy(keySelector, comparer));
}
/// <summary>
/// Moves the items of the collection so that their orders are the same as those of the items provided.
/// </summary>
/// <param name="sortedItems">An <see cref="IEnumerable{T}"/> to provide item orders.</param>
private void InternalSort(IEnumerable<T> sortedItems)
{
var sortedItemsList = sortedItems.ToList();
foreach (var item in sortedItemsList)
{
Move(IndexOf(item), sortedItemsList.IndexOf(item));
}
}
}
然后使用lambda表达式排序
((SortableObservableCollection<CustomClass>)MyList).Sort(s => s.EventDate);
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