静态变量，用于维护内存中Employee对象数量的计数

public class Main /**from NowJava.com - 时  代  Java**/

{

   public static void main(String[] args)

   {

      // 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());
      /**
      n o w  j a v a  . c o m
      **/

      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() 

   {