1. Write the class Employee with the needed instance variables and two constructors: the first receives a values for each instance variable in the order given above, and the second receives a value for only the ID, the name and date of birth of the employee.
2. Add in the class Employee the following methods:
   • display(): displays all information of an employee in the following format exemple:
     =======================
     ID : 123456789
     Name : Fred Flintstone
     Birth : 60/03/12
     Age : 40
     Salary : $120000
     Service: 8 years
     Abcence: 2 days
     Vacation: 13 days
     =======================
   • displayID(): displays the ID and the name of an employee on the same line (ex: 123456789: Fred Flintstone);
   • getSalary(): returns the salary of an employee;
   • getYearService(): returns the number of years in service;
   • getDaysVacation(): returns the number of days of vacation earned;
   • getDaysAbsence(): returns the number of days of absence for illness;
   • setSalary(): changes the salary with a given new value;
   • setYearService(): changes the number of years of service with a given number;
   • setDaysVacation(): changes the number of days of vacation earned with a given number;
   • setDaysAbsence(): changes the number of days of absence for illness with a given number;
   • getAge(): returns the age of the employee;
3. Write a black box test for class Employee and incapsulate it in the class Employee as the main method.

Solution

import java.util.*;
public class Employee {
     
     
     /* instance variables*/
     
     String id; /*(9 digits stored in a string)*/ 
     String name; 
     Date birthdate; 
     int serviceYears; 
     int vacationDays; 
     double salary;
     int absenceDays;     
/*
	Program description.
*/
	public Employee(String id, String name, Date bDate){
	  this.id=id; 
	  this.name=name; 
	  this.birthdate=bDate; 
	  this.serviceYears=0; 
	  this.vacationDays=0; 
	  this.salary=0.0f;
	  this.absenceDays=0;
	}
	
	public Employee(String id, String name, Date bDate, 
	                int servY, int vacD, double salary, 
	                int absD){
	  this.id=id; 
	  this.name=name; 
	  this.birthdate=bDate; 
	  this.serviceYears=servY; 
	  this.vacationDays=vacD; 
	  this.salary=salary;
	  this.absenceDays=absD;
	}

	public void display() {
	// displays all information of an employee; 
		System.out.println("=================================");
		System.out.println("ID      :"+this.id);
		System.out.println("Name    :"+this.name);
		System.out.println("Birth   :"+this.birthdate.getYear()+"/"+
					      (this.birthdate.getMonth()+1)+"/"+
					       this.birthdate.getDate());
		System.out.println("Age     :"+this.getAge());
		System.out.println("Salary  : $"+this.salary);
		System.out.println("Service :"+this.serviceYears+" years");
		System.out.println("Absence :"+this.absenceDays+" days");
		System.out.println("Vacation:"+this.vacationDays+" days");							
		System.out.println("=================================");
	}

	public void displayID() {
	// displays the ID and the name of an employee on the same line; 
		System.out.println(this.id+" "+this.name);
	}

	public double getSalary(){
	// returns the salary of an employee; 
		return this.salary;
	}

	public int getYearService(){
	// returns the number of years in service; 
		return this.serviceYears;
	}

	public int getDaysVacation(){
	// returns the number of days of vacation earned; 
		return this.vacationDays;
	}

	public int getDaysAbsence(){
	// returns the number of days of absence for illness; 
		return this.absenceDays;
	}

	public void setSalary(double salary){
	// changes the salary with a given new value; 
	       this.salary=salary;
	}

	public void setYearService(int years){
	// changes the number of years of service with a given number; 
		this.serviceYears=years;
	}

	public void setDaysVacation(int days){
	// changes the number of days of vacation earned with a given number; 
		this.vacationDays=days;
	}

	public void setDaysAbsence(int days){
	//changes the number of days of absence for illness with a given number; 
		this.absenceDays=days;
	}

	public int getAge(){
	// returns the age of the employee;
		Date		today;
		int		todayYear;
		int		birthYear;
		int		age;
		
		today = new Date();
		todayYear = today.getYear();
		birthYear = this.birthdate.getYear();
		age = todayYear - birthYear;
		if (! this.hadBirthdayThisYear())
			age = age - 1;

		return age;
	}

	private boolean hadBirthdayThisYear() {
	/*   Return true if I have already had my
		birthday this year. */

		Date	today;		int	todayMonth;
		int	myMonth;	int	myDayOfMonth;
		int	todayDayOfMonth;
				
		today = new Date();
		todayMonth = today.getMonth();
		myMonth = this.birthdate.getMonth();
		todayDayOfMonth = today.getDate();
		myDayOfMonth = this.birthdate.getDate();
		if (myMonth < todayMonth)
			return true;
		else if (myMonth > todayMonth)
			return false;
		else if (myDayOfMonth <= todayDayOfMonth)
			return true;
		else
			return false;
	}

	public static void main(String args[]) {
	/* Program statements go here. */
	
		Employee myEmployee1;
		Employee myEmployee2;
	
		myEmployee1 = new Employee("123456789", 
					   "Fred Flintstone", 
					   new Date(60,2,12));
		myEmployee2 = new Employee("987654321", 
					   "John Smith", 
					   new Date(70,4,30),
					   10,3,40000,5);
		System.out.println("Testing the Employee class");		
	        myEmployee1.display();
	        myEmployee1.displayID();
	        System.out.println("Should be 123456789 Fred Flintstone");
	        myEmployee2.display();
	        myEmployee2.displayID();
	        System.out.println("Should be 987654321 John Smith");
	        double mysalary = myEmployee2.getSalary();
	        System.out.println(mysalary + "<< Should be 40,000");
		myEmployee1.setSalary(120000);
	        mysalary = myEmployee1.getSalary();
	        System.out.println(mysalary + "<< Should be 120,000");

		int number = myEmployee2.getYearService();
		System.out.println(number + "<< Should be 10");
	        number = myEmployee2.getDaysVacation();
		System.out.println(number + "<< Should be 3");
		number = myEmployee2.getDaysAbsence();
		System.out.println(number + "<< Should be 5");


		myEmployee1.setYearService(8);
		number = myEmployee1.getYearService();
		System.out.println(number + "<< Should be 8");
		myEmployee1.setDaysVacation(13);
	        number = myEmployee1.getDaysVacation();
		System.out.println(number + "<< Should be 13");
		myEmployee1.setDaysAbsence(2);
		number = myEmployee1.getDaysAbsence();
		System.out.println(number + "<< Should be 2");

	}
}