首先，你需要使用一个Collection类型，它将通知UI任何更改。所以：

  public   const   string  MyListPropertyName =   ListBox; 
 private 列表< string> _listBox =  null ; 
 public 列表< string> ListBox 
 {
 get  
 {
 return  _listBox = _listBox ??  new  List< string>（）; 
} 
 set  
 {
 if （_ listBox ==  value ）
 {
 return ; 
} 
 RaisePropertyChanged（MyListPropertyName）; 
 _listBox =  value ; 
 RaisePropertyChanged（MyListPropertyName）; 
} 
} 

可以更改为：

  public  ObservableCollection< string> ListBox { get ;  set ; } 
 =  new  ObservableCollection< string>（）; 

你的XAML丢失所以我可以看看 SelectedItem 属性是否正确绑定。



我也无法检查你的 DeleteCommand 已正确启用。 RelayCommand 支持启用和禁用绑定按钮。所以你可以像以下一样连线：

  public  RelayCommand DeleteCommand {获得跨度>;  private   set ; } 

 private   void  InitializeRelayCommands（）
 {
 DeleteCommand =  new  RelayCommand 
（（）= >  DeleteSelectedItemListBox（），
（）= >  isSelected）; 
} 

 private   bool  isSelected; 

 private   string  selectedItem; 
 public   string  SelectedItem 
 {
 get  { return  selectedItem; } 
 set  
 {
 Set（ ref  selectedItem，值跨度>）;  //   **见下文 
 isSelected =！string.IsNullOrEmpty（SelectedItem）; 
} 
} 

** ViewModel需要继承Galasoft ViewModelBase 。



现在要删除该项目，您只需要在以下位置添加以下内容，即从中删除 SelectedItem 集合：

  if （！string.IsNullOrEmpty（SelectedItem））
 {
 ListBox.Remove（SelectedItem）; 
 SelectedItem =  string  .Empty; 
} 

最后，为了防止任何混淆，请不要调用集合 ListBox 而是有意义的如 ContactNames 和 SelectedItem as SelectedContact 。现在，您的代码通过以下两个简单的更改进行自我描述：

 ContactNames.Remove（SelectedContact）; 

另外，你正在使用 RelayCommand 的错误命名空间。更改：

 使用 GalaSoft.MvvmLight.Command; 

to：

 使用 GalaSoft.MvvmLight.CommandWpf; 

所以你的 MainWindowViewModel 现在看起来像：

 使用 GalaSoft.MvvmLight; 
使用 GalaSoft.MvvmLight.CommandWpf; 
使用 PhoneBook.View; 
使用 System.Collections.Generic; 
使用 System.Data; 
使用 System.IO; 
使用 System.Linq; 

 namespace  PhoneBook.ViewModel 
 {
 class  MainWindowViewModel：ViewModelBase 
 {
 #region构造函数
 
 public  MainWindowViewModel（）
 {
 InitializeRelayCommands（）; 
 ReadTextFile（）; 
} 

 #endregion 
 
 #region属性
 
 public  ObservableCollection< string> ContactNames { get ;  set ; } 
 =  new  ObservableCollection< string>（）; 

 private   bool  isSelected; 

 private   string  selectedContact; 
 public   string  SelectedContact 
 {
 get  { return  selectedContact; } 
 set  
 {
 Set（ ref  selectedContact，值跨度>）; 
 isSelected =！string.IsNullOrEmpty（selectedContact）; 
} 
} 
  #endregion 
 
 #region方法
 
私有  void  PopUpWindSelectedContact（）
 {

} 

 private   void  DeleteSelectedContactContactNames（）
 {
 string  FileName =（ @  C：\ Users \StanleyM\Desktop\PhoneBook \ PhoneBook \bin\Debug\Personal.text）; 
 StreamReader streamReader =  new  StreamReader（FileName）; 
 string  line =  ; 
 int  Counter = -1; 

 while （（line = streamReader.ReadLine（））！=  null  ）
 {
 foreach （ var  item  in 行）
 {
 if （item == SelectedContact）
 {
 Counter- - ; 
 ContactNames.Remove（line）; 
} 
} 
} 
} 

 public   void  ReadTextFile（）
 {
 string  FileName =（ @   C：\ Users \StanleyM \Desktop\PhoneBook \ PhoneBook \bin\Debug\Personal.text）; 
 DataTable dt =  new  DataTable（  Client 跨度>）; 
 StreamReader streamReader =  new  StreamReader（FileName）; 
 string  line =  ; 
 int 计数器=  0 ; 
 while （（line = streamReader.ReadLine（））！=  null ）
 {
 Counter ++; 
 ContactNames.Add（item：line）; 
} 
} 

私人  void  PopUpWindow（ ）
 {
 AddEditView PopUp =  new  AddEditView（）; 
 PopUp.ShowDialog（）; 
} 

  #endregion 
 
 #region RelayCommand 
 
 public  RelayCommand AddCommand { get ;  private   set ; } 
 public  RelayCommand DeleteCommand { get ;  private   set ; } 

 private   void  InitializeRelayCommands（）
 {
 AddCommand =  new  RelayCommand 
（（）= >  PopUpWindow（））; 

 DeleteCommand =  new  RelayCommand 
（（）= >  DeleteSelectedContactContactNames（），
（）= >  isSelected）; 
} 

  #endregion 
} 
} 

I have a PhoneBook App which adds and save users input in a textfile I am trying to have a function which enable the user to be able to select users details from a Listbox then delete them. As well when you click on the users a screen must popup with the users details and enable you to edit and save again to textfile.
I have tried the DeletedSelectedItemListBox which I have created below in order to be able to delete selected Item from my Listbox.

What I have tried:

using GalaSoft.MvvmLight;
using GalaSoft.MvvmLight.Command;
using PhoneBook.View;
using System.Collections.Generic;
using System.Data;
using System.IO;
using System.Linq;

namespace PhoneBook.ViewModel
{
    class MainWindowViewModel : ViewModelBase
    {
        #region Constructor
        public MainWindowViewModel()
        {
            ReadTextFile();
        }

        #endregion
        #region Properties
        public const string MyListPropertyName = "ListBox";
        private List<string> _listBox = null;
        public List<string> ListBox
        {
            get
            {
                return _listBox = _listBox ?? new List<string>();
            }
            set
            {
                if (_listBox == value)
                {
                    return;
                }
                RaisePropertyChanged(MyListPropertyName);
                _listBox = value;
                RaisePropertyChanged(MyListPropertyName);
            }
          
          
        }
        private string _selectedItem = null;
        public string SelectedItem
        {
            get
            {
                return _selectedItem;
            }
            set
            {
                if (_selectedItem != null)
                {
                    return;
                }
                _selectedItem = value;
                RaisePropertyChanged();
            }
        }



        #endregion

        #region Method

        private void PopUpWindSelectedItem()
        {
           
        }

        private void DeleteSelectedItemListBox()
        {
            string FileName = (@"C: \Users\StanleyM\Desktop\PhoneBook\PhoneBook\bin\Debug\Personal.text");
            StreamReader streamReader = new StreamReader(FileName);
            string line = "";
            int Counter = -1;
            
            while ((line = streamReader.ReadLine()) != null)
            {
                foreach (var item in line)
                {
                    if (item.ToString() == SelectedItem.ToString())
                    {
                        Counter--;
                        ListBox.Remove(line);
                    }
                    
                }
               
            }

        }

        public void ReadTextFile()
        {
            string FileName = (@"C: \Users\StanleyM\Desktop\PhoneBook\PhoneBook\bin\Debug\Personal.text");
            DataTable dt = new DataTable("Client");
            StreamReader streamReader = new StreamReader(FileName);
            string line = "";
            int Counter = 0;
            while ((line = streamReader.ReadLine()) != null)
            {
                Counter++;
                ListBox.Add(item: line);
            }
        }

        private void PopUpWindow()
        {
            AddEditView PopUp = new AddEditView();
            PopUp.ShowDialog();

        }


        #endregion
        #region RelayCommand

        private RelayCommand _addCommand = null;
        public RelayCommand AddCommand
        {
            get
            {
                return _addCommand = _addCommand ?? new RelayCommand(() => PopUpWindow());
            }
        }

        private RelayCommand _deleteCommand = null;
        public RelayCommand DeleteCommand
        {
            get
            {
                return _deleteCommand = _deleteCommand ?? new RelayCommand(() => DeleteSelectedItemListBox());
            }
        }


        #endregion
    }
}

First thing, You need to use a Collection type That will notify the UI of any changes. So this:

public const string MyListPropertyName = "ListBox";
private List<string> _listBox = null;
public List<string> ListBox
{
	get
	{
		return _listBox = _listBox ?? new List<string>();
	}
	set
	{
		if (_listBox == value)
		{
			return;
		}
		RaisePropertyChanged(MyListPropertyName);
		_listBox = value;
		RaisePropertyChanged(MyListPropertyName);
	}
}

can be changed to this:

public ObservableCollection<string> ListBox { get; set; }
    = new ObservableCollection<string>();

Your XAML is missing so I can't see if the SelectedItem property is bound correctly.

I also can not check if your DeleteCommand is enabled correctly. The RelayCommand supports enabling and disabling the bound button. So you could wire it up like:

public RelayCommand DeleteCommand { get; private set; }

private void InitializeRelayCommands()
{
    DeleteCommand  = new RelayCommand
                    (() => DeleteSelectedItemListBox(),
                     () => isSelected);
}

private bool isSelected;

private string selectedItem;
public string SelectedItem
{
    get { return selectedItem; }
    set
    {
        Set(ref selectedItem, value); // ** see below
        isSelected = !string.IsNullOrEmpty(SelectedItem);
    }
}

** The ViewModel needs to inherit the Galasoft ViewModelBase.

Now to delete the item, you only need to add the following where you want to remove the SelectedItem from the collection:

if (!string.IsNullOrEmpty(SelectedItem))
{
    ListBox.Remove(SelectedItem);
    SelectedItem = string.Empty;
}

Lastly, to prevent any confusion, don't call the collection ListBox but instead something meaningful like ContactNames and SelectedItem as SelectedContact. Now your code is self-describing with these two simple changes:

ContactNames.Remove(SelectedContact);

Also, you're using the incorrect namespace for the RelayCommand.Change:

using GalaSoft.MvvmLight.Command;

to:

using GalaSoft.MvvmLight.CommandWpf;

So your MainWindowViewModel now looks like:

using GalaSoft.MvvmLight;
using GalaSoft.MvvmLight.CommandWpf;
using PhoneBook.View;
using System.Collections.Generic;
using System.Data;
using System.IO;
using System.Linq;
 
namespace PhoneBook.ViewModel
{
    class MainWindowViewModel : ViewModelBase
    {
        #region Constructor
        
		public MainWindowViewModel()
        {
			InitializeRelayCommands();
            ReadTextFile();
        }
 
        #endregion
		
        #region Properties
        
        public ObservableCollection<string> ContactNames { get; set; }
            = new ObservableCollection<string>(); 

		private bool isSelected;
		 
		private string selectedContact;
		public string SelectedContact
		{
			get { return selectedContact; }
			set
			{
				Set(ref selectedContact, value);
				isSelected = !string.IsNullOrEmpty(selectedContact);
			}
		}
        #endregion
 
        #region Method
 
        private void PopUpWindSelectedContact()
        {
           
        }
 
        private void DeleteSelectedContactContactNames()
        {
            string FileName = (@"C: \Users\StanleyM\Desktop\PhoneBook\PhoneBook\bin\Debug\Personal.text");
            StreamReader streamReader = new StreamReader(FileName);
            string line = "";
            int Counter = -1;
            
            while ((line = streamReader.ReadLine()) != null)
            {
                foreach (var item in line)
                {
                    if (item == SelectedContact)
                    {
                        Counter--;
                        ContactNames.Remove(line);
                    }
                }
            }
        }
 
        public void ReadTextFile()
        {
            string FileName = (@"C: \Users\StanleyM\Desktop\PhoneBook\PhoneBook\bin\Debug\Personal.text");
            DataTable dt = new DataTable("Client");
            StreamReader streamReader = new StreamReader(FileName);
            string line = "";
            int Counter = 0;
            while ((line = streamReader.ReadLine()) != null)
            {
                Counter++;
                ContactNames.Add(item: line);
            }
        }
 
        private void PopUpWindow()
        {
            AddEditView PopUp = new AddEditView();
            PopUp.ShowDialog();
        }

        #endregion

        #region RelayCommand
 
        public RelayCommand AddCommand { get; private set; }
		public RelayCommand DeleteCommand { get; private set; }
		 
		private void InitializeRelayCommands()
		{
			AddCommand = new RelayCommand
			                (() => PopUpWindow());

			DeleteCommand  = new RelayCommand
							(() => DeleteSelectedContactContactNames(),
							 () => isSelected);
		}

        #endregion
    }
}