Static variable used to maintain a count of the number of Employee objects in memory - Java Object Oriented Design

Java examples for Object Oriented Design:Static

  1. HOME
  2. Java
  3. Object Oriented Design
  4. Static

Description

Static variable used to maintain a count of the number of Employee objects in memory

Demo Code

public class Main 
{
   public static void main(String[] args)
   {//from  ww w  . j a  v  a2  s  .  c  o  m
      // show that count is 0 before creating Employees
      System.out.printf("Employees before instantiation: %d%n",
         Employee.getCount());

      // create two Employees; count should be 2
      Employee e1 = new Employee("Ana", "Bates");
      Employee e2 = new Employee("Mary", "Lady");
   
      // show that count is 2 after creating two Employees
      System.out.printf("%nEmployees after instantiation:%n");
      System.out.printf("via e1.getCount(): %d%n", e1.getCount());
      System.out.printf("via e2.getCount(): %d%n", e2.getCount());
      System.out.printf("via Employee.getCount(): %d%n", 
         Employee.getCount());
   
      // get names of Employees
      System.out.printf("%nEmployee 1: %s %s%nEmployee 2: %s %s%n",
         e1.getFirstName(), e1.getLastName(), 
         e2.getFirstName(), e2.getLastName());
   } 
}

 class Employee 
{
   private static int count = 0; // number of Employees created
   private String firstName;
   private String lastName;

   // initialize Employee, add 1 to static count and 
   // output String indicating that constructor was called
   public Employee(String firstName, String lastName)
   {
      this.firstName = firstName;
      this.lastName = lastName;

      ++count;  // increment static count of employees
      System.out.printf("Employee constructor: %s %s; count = %d%n",
         firstName, lastName, count);
   } 

   // get first name
   public String getFirstName() 
   { 
      return firstName; 
   } 

   // get last name
   public String getLastName() 
   { 
      return lastName; 
   } 

   // static method to get static count value
   public static int getCount() 
   { 
      return count; 
   } 
}

Result


Related Tutorials