ContractorCalculator.java

package payroll;

public class ContractorCalculator extends PayCalculator {
    @Override
    protected double determinePay(double hours, double rate) {
        return hours * rate;
    }
}

HourlyCalculator.java

package payroll;

public class HourlyCalculator extends PayCalculator {
    @Override
    protected double determinePay(double hours, double rate) {
        double overtime = Math.max(0, hours - 40);
        return hours * rate + overtime * rate * 0.5;
    }
}

PayCalculator.java

package payroll;

public abstract class PayCalculator {
    public final double calculate(double hours, double rate) {
        validateHours(hours);
        return determinePay(hours, rate);
    }

    protected void validateHours(double hours) {
        if (hours < 0 || hours > 80) {
            throw new RuntimeException("Hours out of range: " + hours);
        }
    }

    protected abstract double determinePay(double hours, double rate);
}