Difference between Generics and Collections with example

Generics provides the type safe code with re-usability like as algorithm. In algorithms such as sorting, searching, comparing etc. you don’t specify what data type(s) the algorithm operates on. The algorithm can be operates with any types of data. In the same way Generics operate, you can provide different data type to Generics. For example, a sorting algorithm can operates on integer type, decimal type, string type, DateTime type etc.

The .Net framework provides the Generic type for collection classes and these classes ensure that a specific type of data can be stored in the collection. Now, we will discuss the generic type of ArrayList, i.e. List <T> class. Generics are the most powerful feature of C# 2.0. Generics allow us to define type-safe data structures. Generic collection types also generally perform better than the corresponding nongeneric collection types.

A generic collection is strongly typed (type safe), meaning that we can store only one type of data into the collection. This ensures there are no type mismatches at runtime. An additional benefit of generic collection is that performance is better because we do not need to converted them to actual object.

Suppose we want to store only integer values in a collection, we will specify the integer type for the generic parameter. The below code shows how to create a List. Note the data type between less than and greater than symbol <int>. This is how data type is declared at the time of instantiating the List object. In place of int we can use any type of object, like string or a custom business object.

Here I listed some comparesions between Collections and Generics:-

// A class employee

 class Employee

    {

        public int EmpNumber { get; set; }

        public string EmpName { get; set; }

    }

With Collection:-

    ArrayList Obj = new ArrayList();

      // Add to ArrayList

            emp.EmpNumber=101;

            emp.EmpName="Rampal";

            Obj.Add(emp);

     // Display ArrayList Item

           foreach (Object s in Obj)

            {

                //Type-casting. If s is anything other than a student 

                Employee emp = (Employee)s;

                Console.Write(emp.EmpNumber +"   "+ emp.EmpName);

                Console.Write("\n");

            }

     //Fooling Compiler

              Obj.Add("AnyObject");  // It will acept no type safety

With Generics:-

    List ListObj= new yList();

      // Add to List

            emp.EmpNumber=101;

            emp.EmpName="Rampal";

            ListObj.Add(emp);

     // Display List Item

           foreach (Object s in ListObj)

            {

                // No Type-casting.  

                Employee emp = (Employee)s;

                Console.Write(emp.EmpNumber +"   "+ emp.EmpName);

                Console.Write("\n");

            }

     // Cat't make Compiler fool

              ListObj.Add("AnyObject");  // It will not acept no type safety

 Error:-

Now using Code:-

Collections:-

using System;

using System.Collections;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace ConsoleAppDemo

{

    class Program

    {

        static void Main(string[] args)

        {

            Test_ArrayList classObj = new Test_ArrayList();

            while (true)

            {

                // Console.Clear();

                Console.WriteLine("\n");

                Console.WriteLine("1. Add an Item to ArrayList");

                Console.WriteLine("2. Display ArrayList Items");

                Console.WriteLine("3. Exit");

                Console.Write("Select your choice: ");

                int choice = Convert.ToInt32(Console.ReadLine());

                switch (choice)

                {

                    case 1:

                        classObj.Add();

                        break;

                    case 2: classObj.Display();

                        break;

                  

                    case 3: System.Environment.Exit(1);

                        break;

                }

                Console.ReadKey();

            }

        }

    }

    class Employee

    {

        public int EmpNumber { get; set; }

        public string EmpName { get; set; }

    }

    public class Test_ArrayList

    {

        int Num;

        string Name;

        ArrayList Obj = new ArrayList();

        Employee emp = new Employee();

        // Add an Item to ArrayList

        public void Add()

        {

            Console.WriteLine("\nEnter employee number: ");

            Num = int.Parse(Console.ReadLine());

            Console.WriteLine("\nEnter employee Name: ");

            Name = Console.ReadLine();

            emp.EmpNumber=Num;

            emp.EmpName=Name;

            Obj.Add(emp);

             Console.Write("\nAdded successfully! \n");

        }

        // Display Items in the ArrayList

        public void Display()

        {

          

            Console.Write("\nItem in ArrayList");

            Console.Write("\n");

            Console.Write("\nEmpNo"+"   "+ "EmpName\n");

            foreach (Object s in Obj)

            {

                //Type-casting. If s is anything other than a student 

                Employee emp = (Employee)s;

                Console.Write(emp.EmpNumber +"   "+ emp.EmpName);

                Console.Write("\n");

            }

        }

      

    }

}

Output:-

Generics:-

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace ConsoleAppDemo

{

    class Program

    {

        static void Main(string[] args)

        {

            Test_List classObj = new Test_List();

            while (true)

            {

                // Console.Clear();

                Console.WriteLine("\n");

                Console.WriteLine("1. Add an Item to List");

                Console.WriteLine("2. Display List Items");

                Console.WriteLine("3. Exit");

                Console.Write("Select your choice: ");

                int choice = Convert.ToInt32(Console.ReadLine());

                switch (choice)

                {

                    case 1:

                        classObj.Add();

                        break;

                    case 2: classObj.Display();

                        break;

                  

                    case 3: System.Environment.Exit(1);

                        break;

                }

                Console.ReadKey();

            }

        }

    }

    class Employee

    {

        public int EmpNumber { get; set; }

        public string EmpName { get; set; }

    }

    public class Test_List

    {

        int Num;

        string Name;

        List<Employee> ListObj = new List<Employee>();

        Employee emp = new Employee();

        // Add an Item to List

        public void Add()

        {

            Console.WriteLine("\nEnter employee number: ");

            Num = int.Parse(Console.ReadLine());

            Console.WriteLine("\nEnter employee Name: ");

            Name = Console.ReadLine();

            emp.EmpNumber=Num;

            emp.EmpName=Name;

            ListObj.Add(emp);

             Console.Write("\nAdded successfully! \n");

        }

        // Display Items in the List

        public void Display()

        {

          

            Console.Write("\nItem in List");

            Console.Write("\n");

            Console.Write("\nEmpNo"+"   "+ "EmpName\n");

            foreach (Object s in ListObj)

            {

                //no need to type cast since compiler already knows that everything inside

                //this list is a Employee

                Employee emp = (Employee)s;

                Console.Write(emp.EmpNumber +"   "+ emp.EmpName);

                Console.Write("\n");

            }

        }

      

    }

}