ConcurrentDictionary is not updating WPF list box UI.

Question

ConcurrentDictionary is not updating WPF list box UI.

Abirami Ohmprakash 0

Hi Team,

I have to bind the ConcurrentDictionary value to WPF list box. It does not update the UI whenever i add\remove the items. same i have tried with normal dictionary collection. it updates UI properly whenever there is change in the dictionary. I tried to implement INotifyPropertyChanged into that concurrentdictionary. But still I am facing the same issue. UI is not updating. Could you please let me know whether it can be possible in any other way or no option in that.

Viorel 122.6K Reputation points

2024-08-21T09:03:35.2866667+00:00

It looks strange that the normal dictionary works. Show some details to reproduce the problem. Maybe the usage of INotifyPropertyChanged is incorrect.

3 answers

Your answer

Viorel 122.6K Reputation points

2024-08-21T09:03:35.2866667+00:00

It looks strange that the normal dictionary works. Show some details to reproduce the problem. Maybe the usage of INotifyPropertyChanged is incorrect.

Answer 1

Anonymous

Hi,@Abirami Ohmprakash. Welcome to Microsoft Q&A.

ConcurrentDictionary implements IEnumerable but does not implement INotifyCollectionChanged.

If you need the collection data to be able to implement UI notification updates when adding or deleting items, you need to implement INotifyCollectionChanged instead of INotifyPropertyChanged

Related links:

INotifyCollectionChanged Interface (System.Collections.Specialized) | Microsoft Learn

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Abirami Ohmprakash 0 Reputation points

2024-08-21T11:41:10.0466667+00:00

Please help me out i have attached the project i tried

Anonymous

Hi,@Abirami Ohmprakash.

I tweaked your code and added an ObservableDictionary (which implements INotifyCollectionChanged and Dictionary<TKey, TValue>). This allows you to add or delete dictionary sets based on the length of the input box, and always feed back the results to the UI.


public partial class MainWindow : Window, INotifyPropertyChanged

{

    private string _barocdeLength;

    private ObservableDictionary<int, string> _d;

    private ObservableDictionary<int, string> _selectedItems;

    public event PropertyChangedEventHandler PropertyChanged;

 

    public ObservableDictionary<int, string> SelectedItems;

 

    public String BarcodeLength

    {

        get

        {

            return _barocdeLength;

        }

 

        set

        {

            _barocdeLength = value;

            OnPropertyRaised("BarcodeLength");

        }

    }

 

    public ObservableDictionary<int, string> Barcode

    {

        get

        {

            return _d;

        }

 

        set

        {

            _d = value;

            OnPropertyRaised("Barcode");

        }

    }

 

    public ObservableDictionary<int, string> SelctedItems

    {

        get

        {

            return _selectedItems;

        }

 

        set

        {

            _selectedItems = value;

            OnPropertyRaised("SelctedItems");

        }

    }

 

    private void OnPropertyRaised(string propertyname)

    {

        if (PropertyChanged != null)

        {

 

            PropertyChanged(this, new PropertyChangedEventArgs(propertyname));

        }

    }

 

    public MainWindow()

    {

        Barcode = new ObservableDictionary<int, string>();

        Barcode.Add(1, "1");

        Barcode.Add(2, "2");

        Barcode.Add(3, "3");

        Barcode.Add(4, "4");

 

        InitializeComponent();

        this.DataContext = this;

    }

 

    private void BarcodeLength_TextChanged(object sender, TextChangedEventArgs e)

    {

        int barLength = Convert.ToInt32(BarcodeLength);

 

        if (Barcode.Count > barLength)

        {

            for (int i = Barcode.Count; i > barLength; i--)

            {

                Barcode.Remove(i);

            }

        }

        if (Barcode.Count < barLength)

        {

            for (int i = Barcode.Count + 1; i <= barLength; i++)

            {

                Barcode.Add(i, i + "");

            }

        }

    }

 

}


public class ObservableDictionary<TKey, TValue> : Dictionary<TKey, TValue>, INotifyCollectionChanged, INotifyPropertyChanged

{

    public ObservableDictionary(): base()

    { }

 

    private int _index;

    public event NotifyCollectionChangedEventHandler CollectionChanged;

    public event PropertyChangedEventHandler PropertyChanged;

 

    public new KeyCollection Keys

    {

        get { return base.Keys; }

    }

 

    public new ValueCollection Values

    {

        get { return base.Values; }

    }

 

    public new int Count

    {

        get { return base.Count; }

    }

 

    public new TValue this[TKey key]

    {

        get { return this.GetValue(key); }

        set { this.SetValue(key, value); }

    }

 

    public TValue this[int index]

    {

        get { return this.GetIndexValue(index); }

        set { this.SetIndexValue(index, value); }

    }

 

    public new void Add(TKey key, TValue value)

    {

        base.Add(key, value);

        this.OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, this.FindPair(key), _index));

        OnPropertyChanged("Keys");

        OnPropertyChanged("Values");

        OnPropertyChanged("Count");

    }

 

    public new void Clear()

    {

        base.Clear();

        this.OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));

        OnPropertyChanged("Keys");

        OnPropertyChanged("Values");

        OnPropertyChanged("Count");

    }

 

    public new bool Remove(TKey key)

    {

        var pair = this.FindPair(key);

        if (base.Remove(key))

        {

            this.OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, pair, _index));

            OnPropertyChanged("Keys");

            OnPropertyChanged("Values");

            OnPropertyChanged("Count");

            return true;

        }

        return false;

    }

 

    protected void OnCollectionChanged(NotifyCollectionChangedEventArgs e)

    {

        if (this.CollectionChanged != null)

        {

            this.CollectionChanged(this, e);

        }

    }

 

    protected void OnPropertyChanged(string propertyName)

    {

        if (this.PropertyChanged != null)

        {

            this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));

        }

    }

 

    #region Custom methods

    private TValue GetIndexValue(int index)

    {

        for (int i = 0; i < this.Count; i++)

        {

            if (i == index)

            {

                var pair = this.ElementAt(i);

                return pair.Value;

            }

        }

 

        return default(TValue);

    }

 

    private void SetIndexValue(int index, TValue value)

    {

        try

        {

            var pair = this.ElementAtOrDefault(index);

            SetValue(pair.Key, value);

        }

        catch (Exception)

        {

 

        }

    }

 

    private TValue GetValue(TKey key)

    {

        if (base.ContainsKey(key))

        {

            return base[key];

        }

        else

        {

            return default(TValue);

        }

    }

 

    private void SetValue(TKey key, TValue value)

    {

        if (base.ContainsKey(key))

        {

            var pair = this.FindPair(key);

            int index = _index;

            base[key] = value;

            var newpair = this.FindPair(key);

            this.OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Replace, newpair, pair, index));

            OnPropertyChanged("Values");

            OnPropertyChanged("Item[]");

        }

        else

        {

            this.Add(key, value);

        }

    }

 

    private KeyValuePair<TKey, TValue> FindPair(TKey key)

    {

        _index = 0;

        foreach (var item in this)

        {

            if (item.Key.Equals(key))

            {

                return item;

            }

            _index++;

        }

        return default(KeyValuePair<TKey, TValue>);

    }

 

    private int IndexOf(TKey key)

    {

        int index = 0;

        foreach (var item in this)

        {

            if (item.Key.Equals(key))

            {

                return index;

            }

            index++;

 

        }

        return -1;

    }

 

    #endregion

 

}

You could add more functionality to ObservableDictionary as needed.

Anonymous

2024-08-28T08:53:04.83+00:00

Hi,@Abirami Ohmprakash.

Is there any update to the question? Did my answer solve your problem? If so, you could accept it as the answer. It's helpful for community members with related questions.
Abirami Ohmprakash 0 Reputation points

2024-08-29T07:10:47.5166667+00:00

yes, it is working perfectly.
Anonymous

2024-08-29T07:42:37.4533333+00:00

Hi,@Abirami Ohmprakash.

If so, you could accept it as the answer. It's helpful for community members with related questions.

Answer 2

Hi

Thanks for reply. just i tried with INotifyCollectionChanged interface. But i had no luck. Please find the below code changes i have tried and help me in this.

Project_1 - With Dictionary

This is my MainWindow.Xaml,cs

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Windows;

using System.Windows.Controls;

using System.Windows.Data;

using System.Windows.Documents;

using System.Windows.Input;

using System.Windows.Media;

using System.Windows.Media.Imaging;

using System.Windows.Navigation;

using System.Windows.Shapes;

namespace DictionarySample

{

/// <summary>

/// Interaction logic for MainWindow.xaml

/// </summary>

public partial class MainWindow : Window , INotifyPropertyChanged

{

    private string _barocdeLength;

    private Dictionary<int,string> _d;

    private Dictionary<int,string> _selectedItems;

    public event PropertyChangedEventHandler PropertyChanged;

    public String BarcodeLength

    {

        get

        {

            return _barocdeLength;

        }

        set

        {

            _barocdeLength = value;

            OnPropertyRaised("BarcodeLength");

        }

    }

    public Dictionary<int,string> Barcode

    {

        get

        {

            return _d;

        }

        set

        {

            _d = value;

            OnPropertyRaised("Barcode");

        }

       

    }

    public Dictionary<int, string> SelctedItems

    {

        get

        {

            return _selectedItems;

        }

        set

        {

            _selectedItems = value;

            OnPropertyRaised("SelctedItems");

        }

    }



    private void OnPropertyRaised(string propertyname)

    {

        if (PropertyChanged != null)

        {

            PropertyChanged(this, new PropertyChangedEventArgs(propertyname));

        }

    }

    public MainWindow()

    {

        Barcode = new Dictionary<int, string>();

        Barcode.Add(1, "1");

        Barcode.Add(2, "2");

        Barcode.Add(3, "3");

        Barcode.Add(4, "4");

        OnPropertyRaised("Barcode");

   

        InitializeComponent();

        this.DataContext = this;

    

    }

    private void BarcodeLength_TextChanged(object sender, TextChangedEventArgs e)

    {

        Barcode = new Dictionary<int, string>();

         

        for(int i=0;i< Convert.ToInt32(BarcodeLength); i++)

        {

            Barcode.Add(i, i.ToString());   

        }

        OnPropertyRaised("Barcode");

    }

}

}

Xaml file

<Window x:Class="DictionarySample.MainWindow"

    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"

    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"

    xmlns:local="clr-namespace:DictionarySample"

    mc:Ignorable="d"

    Title="MainWindow" Height="450" Width="800">

<Grid>

    <Grid.RowDefinitions>

        <RowDefinition Height="*"/>

        <RowDefinition Height="*"/>

    </Grid.RowDefinitions>

    <TextBox Grid.Row="0" Name="BarcodeLengthtxt" Text="{Binding Path=BarcodeLength,Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" TextChanged="BarcodeLength_TextChanged"/>

    <ListBox Name="listbox1" Grid.Row="1" ItemsSource="{Binding Barcode}" DisplayMemberPath="Value" 

             >



    </ListBox>

</Grid>

</Window>

2. project_2 - concurrentDictionary

MainWindow.Xaml

<Window x:Class="ConcurrentDictionarySample.MainWindow"

    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"

    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"

    xmlns:local="clr-namespace:ConcurrentDictionarySample"

    mc:Ignorable="d"

    Title="MainWindow" Height="450" Width="800">

<Grid>

    <Grid.RowDefinitions>

        <RowDefinition Height="*"/>

        <RowDefinition Height="*"/>

    </Grid.RowDefinitions>

    <TextBox Grid.Row="0" Name="BarcodeLengthtxt" Text="{Binding Path=BarcodeLength,Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" TextChanged="BarcodeLength_TextChanged"/>

    <ListBox Name="listbox1" Grid.Row="1" ItemsSource="{Binding Barcode}" DisplayMemberPath="Value" >

    </ListBox>

</Grid>

</Window>

Mainwindow.xaml.cs

using System;

using System.Collections.Concurrent;

using System.Collections.Generic;

using System.ComponentModel;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Windows;

using System.Windows.Controls;

using System.Windows.Data;

using System.Windows.Documents;

using System.Windows.Input;

using System.Windows.Media;

using System.Windows.Media.Imaging;

using System.Windows.Navigation;

using System.Windows.Shapes;

namespace ConcurrentDictionarySample

{

/// <summary>

/// Interaction logic for MainWindow.xaml

/// </summary>

public partial class MainWindow : Window , INotifyPropertyChanged

{

    private string _barocdeLength;

    private ConcurrentDictionary<int, string> _d;

    private ConcurrentDictionary<int, string> _selectedItems;

    public event PropertyChangedEventHandler PropertyChanged;

    public String BarcodeLength

    {

        get

        {

            return _barocdeLength;

        }

        set

        {

            _barocdeLength = value;

            OnPropertyRaised("BarcodeLength");

        }

    }

    public ConcurrentDictionary<int, string> Barcode

    {

        get

        {

            return _d;

        }

        set

        {

            _d = value;

            OnPropertyRaised("Barcode");

        }

    }

    public ConcurrentDictionary<int, string> SelctedItems

    {

        get

        {

            return _selectedItems;

        }

        set

        {

            _selectedItems = value;

            OnPropertyRaised("SelctedItems");

        }

    }

    private void OnPropertyRaised(string propertyname)

    {

        if (PropertyChanged != null)

        {

            PropertyChanged(this, new PropertyChangedEventArgs(propertyname));

        }

    }

    public MainWindow()

    {

        Barcode = new ConcurrentDictionary<int, string>();

        Barcode.TryAdd(1, "1");

        Barcode.TryAdd(2, "2");

        Barcode.TryAdd(3, "3");

        Barcode.TryAdd(4, "4");

        OnPropertyRaised("Barcode");

        InitializeComponent();

        this.DataContext = this;

    }

    private void BarcodeLength_TextChanged(object sender, TextChangedEventArgs e)

    {

        Barcode = new ConcurrentDictionary<int, string>();

        for (int i = 0; i < Convert.ToInt32(BarcodeLength); i++)

        {

            Barcode.AddOrUpdate(i, i.ToString(), (j, s) => i.ToString());

        }

        OnPropertyRaised("Barcode");

    }

}

}

Answer 3

Viorel 122.6K

Try another approach:

private void BarcodeLength_TextChanged( object sender, TextChangedEventArgs e )
{
    var bc = new ConcurrentDictionary<int, string>( );

    for( int i = 0; i < Convert.ToInt32( BarcodeLength ); i++ )
    {
        bc.AddOrUpdate( i, i.ToString( ), ( j, s ) => i.ToString( ) );
    }

    Barcode = bc;
}

Abirami Ohmprakash 0 Reputation points

2024-08-21T11:59:44.98+00:00

I have tried this. but it does not update the UI. But when I snoop the UI, collection contains latest data. But Ui only not updating. still it shows 4 items alone. It should display

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ConcurrentDictionary is not updating WPF list box UI.

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