[英]WPF PropertyChanged code error: cannot implement 'System.ComponentModel.INotifyPropertyChanged
i have this code: 我有此代码:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.ComponentModel;
using System.Collections.Specialized;
using System.Collections.ObjectModel;
namespace Bix
{
public class SettingsDataObject
{
private int id;
public int Id
{
get { return id; }
set { id = value == 0 ? Db.GetNextSettingsId() : value; }
}
private string adminEmail; public string AdminEmail {
get { return adminEmail; }
set { adminEmail = value; }
}
private int state; public int State { get { return state; } set { state = value == 0 ? 1 : value; } }
public object[] GetArray()
{
return new object[] { id, adminEmail, state };
}
public SettingsDataObject()
{
}
}
public class SettingsUIObjects : ObservableCollection<SettingsUIObject>,INotifyPropertyChanged
{
protected override void InsertItem(int index, SettingsUIObject item)
{
base.InsertItem(index, item);
// handle any EndEdit events relating to this item
item.ItemEndEdit += new SettingsUIObject.ItemEndEditEventHandler(ItemEndEditHandler);
item.PropertyChanged += new SettingsUIObject.PropertyChangedEventHandler(PropertyChanged);
}
public void ItemEndEditHandler(IEditableObject sender)
{
// simply forward any EndEdit events
if (ItemEndEdit != null)
{
ItemEndEdit(sender);
}
}
public event SettingsUIObject.ItemEndEditEventHandler ItemEndEdit;
public event SettingsUIObject.PropertyChangedEventHandler PropertyChanged;
}
public class SettingsDataProvider
{
private DataAccessLayer dl;
public SettingsDataProvider()
{
dl = new DataAccessLayer();
}
public SettingsUIObjects GetSettings()
{
try
{
SettingsUIObjects objs = new SettingsUIObjects();
List<SettingsDataObject> objDataObjects = dl.GetSettings();
foreach (SettingsDataObject obj in objDataObjects)
{
objs.Add(new SettingsUIObject(obj));
}
objs.ItemEndEdit += new SettingsUIObject.ItemEndEditEventHandler(SettingsItemEndEdit);
objs.CollectionChanged += new
NotifyCollectionChangedEventHandler(SettingsCollectionChanged);
objs.PropertyChanged += new SettingsUIObject.PropertyChangedEventHandler(SettingsPropertyChanged);
return objs;
}
catch (Exception) { return new SettingsUIObjects(); }
}
void SettingsItemEndEdit(IEditableObject sender)
{
SettingsUIObject obj = sender as SettingsUIObject;
// use the data access layer to update the wrapped data object
dl.UpdateSettings(obj.GetDataObject());
}
void SettingsPropertyChanged(INotifyPropertyChanged sender, PropertyChangedEventArgs e)
{
SettingsUIObject obj = sender as SettingsUIObject;
// use the data access layer to update the wrapped data object
dl.UpdateSettings(obj.GetDataObject());
}
void SettingsCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
{
if (e.Action == NotifyCollectionChangedAction.Remove)
{
foreach (object item in e.OldItems)
{
SettingsUIObject obj = item as SettingsUIObject;
// use the data access layer to delete the wrapped data object
dl.DeleteSettings(obj.GetDataObject());
}
}
if (e.Action == NotifyCollectionChangedAction.Add)
{
foreach (object item in e.NewItems)
{
SettingsUIObject obj = item as SettingsUIObject;
// use the data access layer to delete the wrapped data object
dl.UpdateSettings(obj.GetDataObject());
}
}
}
}
public class SettingsUIObject : IEditableObject, INotifyPropertyChanged
{
private SettingsDataObject obj;
public SettingsUIObject(SettingsDataObject o)
{
obj = o;
}
public SettingsDataObject GetDataObject()
{
return obj;
}
public int Id { get { return obj.Id; } set { obj.Id = value; } }
public string AdminEmail {
get { return obj.AdminEmail; }
set { obj.AdminEmail = value; }
}
public delegate void ItemEndEditEventHandler(IEditableObject sender);
public event ItemEndEditEventHandler ItemEndEdit;
#region IEditableObject Members
public void BeginEdit() { }
public void CancelEdit() { }
public void EndEdit()
{
if (ItemEndEdit != null)
{
ItemEndEdit(this);
}
}
#endregion
public delegate void PropertyChangedEventHandler(INotifyPropertyChanged sender, PropertyChangedEventArgs e);
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChanged(string info)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(info));
}
}
}
}
and i keep getting the compile error: 而且我不断收到编译错误:
'Bix.SettingsUIObject' does not implement interface member 'System.ComponentModel.INotifyPropertyChanged.PropertyChanged'. 'Bix.SettingsUIObject'未实现接口成员'System.ComponentModel.INotifyPropertyChanged.PropertyChanged'。 'Bix.SettingsUIObject.PropertyChanged' cannot implement 'System.ComponentModel.INotifyPropertyChanged.PropertyChanged' because it does not have the matching return type of 'System.ComponentModel.PropertyChangedEventHandler'
'Bix.SettingsUIObject.PropertyChanged'无法实现'System.ComponentModel.INotifyPropertyChanged.PropertyChanged',因为它没有匹配的返回类型'System.ComponentModel.PropertyChangedEventHandler'
can anyone tell me why? 谁能告诉我为什么?
thanks 谢谢
Orson 奥森
public delegate void PropertyChangedEventHandler(INotifyPropertyChanged sender, PropertyChangedEventArgs e);
public event PropertyChangedEventHandler PropertyChanged;
Your code redeclares a PropertyChangedEventHandler
delegate, which hides the one declared in System.ComponentModel
. 您的代码重新声明了
PropertyChangedEventHandler
委托,该委托隐藏了System.ComponentModel
声明的委托。 So your event is of type SettingsUIObject.PropertyChangedEventHandler
, not System.ComponentModel.PropertyChangedEventHandler
. 因此,您的事件类型为
SettingsUIObject.PropertyChangedEventHandler
,而不是System.ComponentModel.PropertyChangedEventHandler
。 Since the type doesn't match the one declared in INotifyPropertyChanged
, your PropertyChanged
event doesn't a valid implementation of the interface. 由于类型与
INotifyPropertyChanged
声明的类型不匹配,因此PropertyChanged
事件不是该接口的有效实现。
Just remove your PropertyChangedEventHandler
delegate and it should work fine. 只需删除您的
PropertyChangedEventHandler
委托,它就可以正常工作。
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