Static Variables and Methods

Static Variables

Accessing static instance variables

void main() {
  
  
   // Static instance variables 
  //-----------------------------
  
  var employee1 = Employee();
  
  
  
  employee1.id =1;
  employee1.name="John Doe";
  
  Employee.companyname="B";
    
  
  print(employee1.id);
  
  print(employee1.name);
  
  print(Employee.companyname);
  
 
}



class Employee{
  
  int id;
  
  String name;
  
  
  static String companyname="A";
  
 
  
}

Without creating an instance

void main() {
  
  
   // Static instance variables 
  //-----------------------------
  
  
  Employee.companyname="B";
  
  print(Employee.companyname);

}



class Employee{
  
  int id;
  
  String name;
  
  
  static String companyname="A";
  
 
  
}

Accessing inside a method

void main() {
  
  
   // Static instance variables 
  //-----------------------------
  
  var employee1 = Employee();
  
  
  
   employee1.id =1;
  employee1.name="John Doe";
  
  Employee.companyname="B";
    
  
//   print(employee1.id);
  
//   print(employee1.name);
  
  print(Employee.companyname);
  
  employee1.test();
  
}



class Employee{
  
  int id;
  
  String name;
  
  
  static String companyname="A";
  
  void test(){
  
     // Accessing  static fields inside a method 
    
    print(Employee.companyname);
    
    
    
  }
  
  
}

• Static Variables are not related to object, they are related to Class

• Static Variables are sometimes referred to as Class variables

• There is no need for creating an object to access static variables

• You can't access static variables via instances

• Single copy of static variables is shared among all the instances

• The purpose of using static variables is for memory management and memory efficiency

• Static Variables are not initialised (i.e. not given a memory segmentation ) unless they are used in the program [ Lazy initialisation ]

Static methods

Invoking static methods

void main() {
  
  
   // Static methods  
  //-----------------------------
  
  var employee1 = Employee();
  
  employee1.id =1;
  employee1.name ="John Doe";
  
  Employee.salary(30);
  
}



class Employee{
  
  int id;
  
  String name;
  
 
  
  static void salary(int perDayWage){
    
      
     print("Salary : ${perDayWage*20}");
          
   
  }
  
  
  
 
  
}

Invoking without creating an instance

void main() {
   
  Employee.salary(30);

}

class Employee{
  
  int id;
  
  String name;
  
  static void salary(int perDayWage){
      
     print("Salary : ${perDayWage*20}");
          
   
  }
  
 
  
}

• Static methods are not related to objects , they are related to Class

• Static methods are sometimes referred as Class methods

• There is no need for creating an instance to invoke a static method

• You can't invoke static method on an instance

• You cannot invoke a method from within a static method

• You can't access instance variables from within static methods , you can't even use "this" keyword inside static methods