Иерархия классов

public interface Worker {
 
    String getLastName();
 
    double getBaseSalary();
 
    double getWageRate();
 
    WageCalculator getWageCalculator();
}

public interface WageCalculator {
    double calculate(int hours);
}

public class LabourWorker implements Worker {
 
    private final String lastName;
    private final double baseSalary;
    private final double wageRate;
 
    private final WageCalculator wageCalculator = new WageCalculator() {
        @Override
        public double calculate(int hours) {
            double maxWagedHours = 8 * getWageRate();
            double wagedHours = hours >= maxWagedHours ? maxWagedHours : hours;
            double bonusHours = hours > maxWagedHours ? hours - maxWagedHours : 0;
            return getBaseSalary() * (wagedHours + bonusHours * 1.5);
        }
    };
 
    public LabourWorker(String lastName, double baseSalary, double wageRate) {
        this.lastName = lastName;
        this.baseSalary = baseSalary;
        this.wageRate = wageRate;
    }
 
    @Override
    public String getLastName() {
        return lastName;
    }
 
    @Override
    public double getBaseSalary() {
        return baseSalary;
    }
 
    @Override
    public double getWageRate() {
        return wageRate;
    }
 
    @Override
    public WageCalculator getWageCalculator() {
        return wageCalculator;
    }
 
    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (!(o instanceof LabourWorker)) return false;
        LabourWorker that = (LabourWorker) o;
        return lastName.equals(that.lastName);
    }
 
    @Override
    public int hashCode() {
        return lastName.hashCode();
    }
 
    @Override
    public String toString() {
        return "LabourWorker{" +
                "lastName='" + lastName + '\'' +
                ", baseSalary=" + baseSalary +
                ", wageRate=" + wageRate +
                '}';
    }
}

public class ManagerWorker implements Worker {
 
    private final String lastName;
    private final double baseSalary;
    private final double wageRate;
    private final double bonus;
 
    private final WageCalculator wageCalculator = new WageCalculator() {
        @Override
        public double calculate(int hours) {
            return getBaseSalary() * 8 * getBonus();
        }
    };
 
    public ManagerWorker(String lastName, double baseSalary, double wageRate, double bonus) {
        this.lastName = lastName;
        this.baseSalary = baseSalary;
        this.wageRate = wageRate;
        this.bonus = bonus;
    }
 
    @Override
    public String getLastName() {
        return lastName;
    }
 
    @Override
    public double getBaseSalary() {
        return baseSalary;
    }
 
    @Override
    public double getWageRate() {
        return wageRate;
    }
 
    public double getBonus() {
        return bonus;
    }
 
    @Override
    public WageCalculator getWageCalculator() {
        return wageCalculator;
    }
 
    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (!(o instanceof ManagerWorker)) return false;
        ManagerWorker that = (ManagerWorker) o;
        return lastName.equals(that.lastName);
    }
 
    @Override
    public int hashCode() {
        return lastName.hashCode();
    }
 
    @Override
    public String toString() {
        return "ManagerWorker{" +
                "bonus=" + bonus +
                ", wageRate=" + wageRate +
                ", baseSalary=" + baseSalary +
                ", lastName='" + lastName + '\'' +
                '}';
    }
 
}

import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
 
/**
 *
 */
public class WorkerService {
    private final int maxWorkers;
    private final Map<String, Worker> workers = new HashMap<>();
 
    public WorkerService(int maxWorkers) {
        this.maxWorkers = maxWorkers;
    }
 
    public synchronized void add(Worker worker) {
        if (workers.size() > maxWorkers) {
            throw new ArrayIndexOutOfBoundsException("Maximum amount of workers exceeded");
        }
        workers.put(worker.getLastName(), worker);
    }
 
    public void addAll(Iterable<Worker> workers) {
        for (Worker worker : workers) {
            add(worker);
        }
    }
 
    public Collection<Worker> getAll() {
        return workers.values();
    }
}

import java.util.Random;
 
/**
 *
 */
public class Launcher {
 
    private static final Random RANDOM = new Random();
    private static final double WAGE_RATES[] = {1.0, 0.5, 0.25};
 
    private static double getRandomWageRate() {
        return WAGE_RATES[RANDOM.nextInt(WAGE_RATES.length)];
    }
 
    private static double getRandomBaseSalary() {
        return 10 + RANDOM.nextInt(20);
    }
 
    private static double getRandomBonus() {
        return 1.0 + ((10 + RANDOM.nextInt(30)) / 100.0);
    }
 
    public static void main(String[] args) {
        final WorkerService workerService = new WorkerService(100);
 
        for (int i = 0; i < 100; ++i) {
            final Worker worker;
            if (i % 3 == 0) {
                worker = new ManagerWorker("ManagerWorker" + i,
                        getRandomBaseSalary(),
                        getRandomWageRate(),
                        getRandomBonus());
            } else {
                worker = new LabourWorker("LabourWorker" + i,
                        getRandomBaseSalary(),
                        getRandomWageRate());
            }
            workerService.add(worker);
        }
 
        for (final Worker worker : workerService.getAll()) {
            final int hoursWorked = 4 + RANDOM.nextInt(12);
            System.out.println(worker.getLastName() + " will get " +
                    worker.getWageCalculator().calculate(hoursWorked) +
                    " for " + hoursWorked + " hours. (" + worker + ")");
        }
    }
}