Add two custom exceptionsclass. One should be checked exception and other should be unchecked exception. You have to handle both exceptions your code.

class BaseSalariedCommissionEmployee extends Employee { //attributes private double baseSalary; private double sales; private double commissionPercent; //constructor public BaseSalariedCommissionEmployee(String name, Date birthDate, double baseSalary, double sales, double commissionPercent) { super(name, birthDate); this.baseSalary = baseSalary; this.sales = sales; this.commissionPercent = commissionPercent; } @Override public double pay() { return baseSalary + sales*commissionPercent/100; } @Override public String toString() { return "BaseSalariedCommissionEmployee [baseSalary=" + baseSalary + ", sales=" + sales + ", commissionPercent=" + commissionPercent + ", pay()=$" + pay() + "]"; } } class CommissionEmployee extends Employee { //attributes private double sales; private double commissionPercent; //constructor public CommissionEmployee(String name, Date birthDate, double sales, double commissionPercent) { super(name, birthDate); this.sales = sales; this.commissionPercent = commissionPercent; } @Override public double pay() { return sales * commissionPercent / 100; } @Override public String toString() { return "CommissionEmployee [sales=" + sales + ", commissionPercent=" + commissionPercent + ", pay()=$" + pay() + "]"; } } public class Date { private int Day; private int Month; private int Year; public Date(int Day, int Mont, int Year) {setYear(Year); } public Date() { } public void setDay(int Day) { if (Day <= 30) { this.Day = Day; } else { System.out.println("Invalid input"); } } public void setMonth(int Month) { if (Month<=12) { this.Month=Month; } else { System.out.println("Invalid input"); } } public void setYear(int year) { this.Year=Year; } public int getDay() { return Day; } public int getMonth() { return Month; } public int getYear() { return Year; } } abstract class Employee { private String name; private Date birthDate; public Employee(String name, Date birthDate) {this.name = name; this.birthDate = birthDate; } public Date getBirthDate(){ return birthDate; } //abstract method abstract double pay(); } class HourlyEmployee extends Employee { //attributes private int workedHours; private double wagePerHour; //constructor public HourlyEmployee(String name, Date birthDate, int workedHours, double wagePerHour) { super(name, birthDate); this.workedHours = workedHours; this.wagePerHour = wagePerHour; } @Override public double pay() { if(workedHours > 40) return 40 * wagePerHour + (workedHours - 40) * wagePerHour * 1.5; return workedHours * wagePerHour; } @Override public String toString() { return "HourlyEmployee [workedHours=" + workedHours + ", wagePerHour=" + wagePerHour + ", pay()=$" + pay() + "]"; } } class PieceWorker extends Employee { //attributes private double wage; private int pieces; //constructor public PieceWorker(String name, Date birthDate, double wage, int pieces) { super(name, birthDate); this.wage = wage; this.pieces = pieces; } @Override public double pay() { return wage*pieces; } @Override public String toString() { return "PieceWorker [wage=" + wage + ", pieces=" + pieces + ", pay()=$" + pay() + "]"; } }class SalariedEmployee extends Employee { private double basicSalary; public SalariedEmployee(String name, Date birthDate, double basicSalary) { super(name, birthDate); this.basicSalary = basicSalary; } @Override public double pay() { return basicSalary; } @Override public String toString() { return "SalariedEmployee [basicSalary=" + basicSalary + ", pay()=$" + pay() + "]"; } } public class TestEmployees { public static void main(String[] args){ Employee emp[] = new Employee[5]; emp[0] = new SalariedEmployee("Ali", new Date(5, 8, 1990), 5000); emp[1] = new HourlyEmployee("Ahmad", new Date(19, 6, 2000), 100, 10); emp[2] = new CommissionEmployee("Ahsan", new Date(10, 11, 1990), 12000, 10); emp[3] = new BaseSalariedCommissionEmployee("Saad", new Date(10, 1, 1990), 3000, 12000, 10); emp[4] = new PieceWorker("Qasim", new Date(10, 11, 2000), 300, 1200); Date date = new Date(); for(int i=0; i