Use of Equals() method in ArrayList in C# | Importance of Equals() method in C# .NET

ArrayList contains method  in c#

Concept : Use of Equals()  method in C#

Look the below code and output

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

namespace ConsoleApplication1
{
    class employee
    {
        public string name;
        public string id;
        public employee(String name, String id)
        {
            this.name = name;
           
            this.id = id;
        }
      
    }
   
    class ArrayTest
    {
    static void Main()
        {
            ArrayList ar = new ArrayList();
           ar.Add("kumud");
           ar.Add("Raju");
           ar.Add("yugdeep");
      
          Console.WriteLine("Array Contain " + ar.Contains("kumud");
    }

    }
}


Output :
 
   Array Contain  True


Now again look the code below :

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

namespace ConsoleApplication1
{
    class employee
    {
        public string name;
        public string id;
        public employee(String name, String id)
        {
            this.name = name;
           
            this.id = id;
        }
   
    }
   
    class ArrayTest
    {
    static void Main()
        {
              ar.Add(new employee("sandeep","3"));
              ar.Add(new employee("yugdeep", "3"));
              ar.Add(new employee("kumud", "3"));
           
               Console.WriteLine("Array Contain " + ar.Contains(new employee("sandeep","3"));

        }

    }
}
 

Output :

Array Contain False

Concept :  In case of when we adding string object its come true but in case of adding employe and searching for that particular
           object it comes false , reason behind is that string by default override the object's Equal() method in such way that
          it compare two string and return true but in case of employee class object there is no equals() method override
          ArrayList contain method search the Equals() method in object .so in case of employee there is no Equals() method mechanism
          so it coming False

Now we override Equals() method


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

namespace ConsoleApplication1
{
    class employee
    {
        public string name;
        public string id;
        public employee(String name, String id)
        {
            this.name = name;
           
            this.id = id;
        }
        public override bool Equals(Object o)
        {
           
            employee e = (employee)o;
          return (e.name.Equals(this.name));
          
        }
      
    }
   
    class ArrayTest
    {
    static void Main()
        {
             ArrayList ar = new ArrayList();
           ar.Add(new employee("sandeep","3"));
             ar.Add(new employee("yugdeep", "3"));
             ar.Add(new employee("kumud", "3"));
      
              Console.WriteLine("Array Contain " + ar.Contains(new employee("sandeep","3"));    }

    }
}

Output :

Array Contain True