Create Value Changed event for dictionary in c#

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I created a dictionary in winform like this:

C#

public Dictionary<string, int> dicMemory = new Dictionary<string, int>();

I want to create ValueChanged event when I update value in dicMemory to know which value changed,and I can catch event like this:

C#

dicMemory["Value_0"].ValueChanged += Value0_Changed

C#

dicMemory["Value_1"].ValueChanged += Value1_Changed

C#

...

What is the best way to do this. Thanks in advance.

Posted 6-Aug-15 0:11am

Member 11735196

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Maciej Los 6-Aug-15 6:38am

I'm afraid that Dictionary class does not provide functionality to add custom event while value is changed.

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F. Xaver · Answer 1 · 2015-08-06T01:01:00

Solution 1

Write your own extended Dictionary class.
Inherit from Dictionary.
Shadow all the needed Methods (like .Item) and raise your event when a value gets changed.

Posted 6-Aug-15 1:01am

F. Xaver

Alexander Dymshyts · Answer 2 · 2015-08-06T01:02:00

Solution 2

You can create your own dictionary, that will inherit from Dictionary. There you can implement valueChanged event and others and then you would be able to do something like:

C#

CustomDictionary<int,> name = new CustomDictionary();
name.SomeEvent += someMethod;

Posted 6-Aug-15 1:02am

Alexander Dymshyts

sreeyush sudhakaran · Answer 3 · 2015-08-06T01:42:00

Custom Dictionary Sample code :

C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace DictonaryValueChanged
{
    public class ExtendedDictonary<Tkey,Tvalue> : Dictionary<Tkey,Tvalue>
    {
        public Dictionary<Tkey,Tvalue> Items = new Dictionary<Tkey,Tvalue>();
        public ExtendedDictonary():base(){}
        ExtendedDictonary(int capacity) : base(capacity) { }
        //
         // Do all your implementations here...
        //

        public event EventHandler ValueChanged;

        public void OnValueChanged(Object sender,EventArgs e)
        {
            EventHandler handler = ValueChanged;
            if (null != handler) handler(this, EventArgs.Empty);
        }

        public void AddItem(TKey key, TValue value)
        {
            try
            {
                Items.Add(key, value);
                OnValueChanged(this, EventArgs.Empty);
            }
            catch (Exception ex)
            {
                
                throw ex;
            }
            
        }

        //
          // Similarly Do implementation for Update , Delete and Value Changed checks (Note: Value change can be monitored using a thread)
        //
    }
}

Using this Dictionary in your code :

C#

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace DictonaryValueChanged
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {

            ExtendedDictonary<string,int> dicMemory = new ExtendedDictonary<string,int>();
            dicMemory.ValueChanged += new EventHandler(DictonaryOnValuedChanged);

            dicMemory.AddItem("Hai", 1);
        }

        private void DictonaryOnValuedChanged(Object sender, EventArgs e)
        {
            string test = sender.ToString();
        }
    }
}

Jawad Siddiqui · Answer 4 · 2015-08-06T02:23:00

Solution 4

It is very easy by using below

dicMemory += new EventHandler(dicMemoryEvent);



private void dicMemoryEvent(Object sender, EventArgs e)
        {
            string test = sender.ToString();
        }

Posted 6-Aug-15 2:23am

Jawad Siddiqui

Comments

Member 11735196 6-Aug-15 10:29am

Thank you for your help, but I want to create the events for each TKey of Dictionary like this:

dicMemory["Key_0"].ValueChanged += new EventHandler(Key0_ValueChanged)
dicMemory["Key_1"].ValueChanged += new EventHandler(Key1_ValueChanged)
dicMemory["Key_2"].ValueChanged += new EventHandler(Key2_ValueChanged)

I want to raise event of Tkey which I needed when TValue gets changed, not all Tkey. Do you understand me?

Member 11735196 · Answer 5 · 2015-08-06T15:19:00

I want to create the events for each TKey of Dictionary like this:

C#

dicMemory["Key_0"].ValueChanged += new EventHandler(Key0_ValueChanged)
dicMemory["Key_1"].ValueChanged += new EventHandler(Key1_ValueChanged)
dicMemory["Key_2"].ValueChanged += new EventHandler(Key2_ValueChanged)

Private void Key0_ValueChanged(Object sender, EventArgs e)
    {
       // do something here
    }

Private void Key1_ValueChanged(Object sender, EventArgs e)
    {
       // do something here
    }

Private void Key2_ValueChanged(Object sender, EventArgs e)
    {
       // do something here
    }

when Value_0 changed, Key0_ValueChanged method implement
when Value_1 changed, Key1_ValueChanged method implement
when Value_2 changed, Key2_ValueChanged method implement