Static Keyword
Static keyword can be used in 3 scenarios,
1. For Data Members
It is a variable which belongs to the Class. A single copy can be shared by all
instances of a class. For the used of static variables, creation of instance is
not required.
Access using ClassName.VariableName
Unlike instance variables which are accessed as ObjectName.VariableName.
Static Data Member - > StaticDataMember.cs
using
System;
using
System.Collections.Generic;
using
System.Linq;
using
System.Text;
using
System.Threading.Tasks;
namespace
StaticKeyWordDemo.Classes
{
public class StaticDataMember
{
private int
StudId;
private static
int nextStudId = 1;
public StaticDataMember()
{
StudId =
nextStudId++;
}
public void
PrintRecord()
{
Console.WriteLine("Student Id is {0}", StudId);
}
}
}
using
StaticKeyWordDemo.Classes;
using
System;
using
System.Collections.Generic;
using
System.Linq;
using
System.Text;
using
System.Threading.Tasks;
namespace
StaticKeyWordDemo
{
class StaticKeyword
{
static void
Main(string[] args)
{
StaticDataMember sd1 =
new StaticDataMember();
StaticDataMember sd2 =
new StaticDataMember();
//printing
Console.WriteLine("***
Static Keyword Demo ***");
sd1.PrintRecord();
sd2.PrintRecord();
Console.ReadKey();
}
}
}
Output
![Image-1.jpg]()
2. tatic Method Member
Like any static member, static method belongs to the class(not object). Accessed
using ClassName.MethodName.It is a class method. For using static methods,
Creation of instance is not necessary. A static method only access other static
data and methods, Static methods can not access data members and members method
directly – they must use an object reference.
Static Data Members - > StaticMethodMember.cs
using
System;
using
System.Collections.Generic;
using
System.Linq;
using
System.Text;
using
System.Threading.Tasks;
namespace
StaticKeyWordDemo.Classes
{
public class StaticMethodMember
{
private int
EmpId;
private static
int nextEmpId = 100;
public static
void PrintNextEmp()
{
Console.WriteLine("Next Employee Id is {0}",
nextEmpId);
}
}
}
using
StaticKeyWordDemo.Classes;
using
System;
using
System.Collections.Generic;
using
System.Linq;
using
System.Text;
using
System.Threading.Tasks;
namespace
StaticKeyWordDemo
{
class StaticKeyword
{
static void
Main(string[] args)
{
Console.WriteLine("***
Static Keyword Demo ***");
StaticMethodMember.PrintNextEmp();
Console.ReadKey();
}
}
}
Output
![Image-2.jpg]()
3. Static Constructor
A class can have only one static member. Static constructor can not have any
parameter. Static constructor can not have any access specifier, not even
private. It is used to initialize the static data members of the class. For any
number of object creation, the static constructor gets executed only once.
The static constructor gets excuted when the class is used or refernced for the
very first time in the applocation. It can not be invoked by the programmer
explicitly.
Static Constructor - > StaticConstructor.cs
using
System;
using
System.Collections.Generic;
using
System.Linq;
using
System.Text;
using
System.Threading.Tasks;
namespace
StaticKeyWordDemo.Classes
{
public class StaticConstructor
{
private static
int nextEmpId;
private int
EmpId;
private string
EmpName = "Krishn";
static StaticConstructor()
{
nextEmpId = 100;
}
public StaticConstructor()
{
EmpId = nextEmpId++;
}
public StaticConstructor(string
empName)
{
EmpId = nextEmpId++;
this.EmpName = empName;
}
public void
PrintInfo()
{
Console.WriteLine("EmpId : {0}", EmpId);
Console.WriteLine("EmpName : {0}", EmpName);
}
}
}
using
StaticKeyWordDemo.Classes;
using
System;
using
System.Collections.Generic;
using
System.Linq;
using
System.Text;
using
System.Threading.Tasks;
namespace
StaticKeyWordDemo
{
class StaticKeyword
{
static void
Main(string[] args)
{
Console.WriteLine("***
Static Keyword Demo ***");
StaticConstructor sc1 =
new
StaticConstructor();
sc1.PrintInfo();
Console.WriteLine();
StaticConstructor sc2 =
new
StaticConstructor("Jeetendra");
sc2.PrintInfo();
Console.ReadKey();
}
}
}
Output
![Image-3.jpg]()
The first time during class load for execution, the nexEmpId gets initialized to
100. after that every instance of StaticConstructor class created using either
of the constructors, the nextEmpId is assigned to the instance field empId and
then incremented. Thus this code generates a unique number stating from 100 and
assigns it to each individual StaticConstructor object as its empId.
Static constructor is called implicitly only once in the lifetime of the
application. Subsequently only the default or parameterised constructor is
called, depending on the way of object created.