Static Keyword can be used with
1. Classes
2. Members
3. Methods/Properties/Events
1.
Classes
When a class is declared as static it can have only static members
It can not be instantiated (It is sealed class).
Example to illustrate static class
static class JobLocation
{
public static string
GetJobLocation()
{
return "H.No. Abc Test Street";
}
}
2. Members
Static variables belongs to class.
Non Static members belong to instance i.e. object of a class.
A class can have static as well as non Static members.
When an instance of a class is created it will have a separate copy of non static Members but a single copy of static member which belongs to class and not to the instance of that class.
It is not possible to use this keyword with static members.
class Employee
{
int
employeeID;
static string companyName;
}
3. Methods/Properties/Events
Static methods can only use static Members.
A class can have static methods as well as non Static methods.
class Employee
{
int
employeeID;
static string companyName;
public static void
EmployeeData()
{
// we can
access companyName here as it is static.
// we can
not access employeeID as it is non static.
companyName = "Test Company";
}
public void EmployeeDetails()
{
EmployeeData();
employeeID = 2;
}
public void PrintEmployeeDetails()
{
Console.WriteLine("Comapny Name is " + companyName);
Console.WriteLine("EmployeeID is " + employeeID);
}
}
class Program
{
static void Main(string[]
args)
{
Employee
emp = new Employee();
emp.EmployeeDetails();
emp.PrintEmployeeDetails();
Console.Read();
}
}
And to directly call static method we use class and not the instance
class Employee
{
int
employeeID;
static string companyName;
public static void
EmployeeData()
{
// we can
access companyName here as it is static.
// we can
not access employeeID as it is non static.
companyName = "Test Company";
}
public void EmployeeDetails()
{
employeeID = 2;
}
public void PrintEmployeeDetails()
{
Console.WriteLine("Comapny Name is " + companyName);
Console.WriteLine("EmployeeID is " + employeeID);
}
}
class Program
{
static void Main(string[]
args)
{
Employee.EmployeeData();
Employee
emp = new Employee();
emp.EmployeeDetails();
emp.PrintEmployeeDetails();
Console.Read();
}
}
4. Static Constructors
Static Constructors are used to initialize static Data.
Static Constructors can not have access specifier ( Not even private) and cannot be overloaded.
class Employee
{
int
employeeID;
static string companyName;
static
Employee()
{
// we can
access companyName here as it is static.
// we can
not access employeeID as it is non static.
Console.WriteLine("In Employee Class static constructor");
}
}
class Program
{
static void Main(string[]
args)
{
Employee
emp = new Employee();
Console.Read();
}
}
