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
With Collection:-
With Generics:-
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; }
}
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
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");
}
}
}
}
