CashRegister.java

/**
 * A cash register totals up sales and computes change due.
 */
public class CashRegister {
    public static final double QUARTER_VALUE = 0.25;
    public static final double DIME_VALUE = 0.10;
    public static final double NICKLE_VALUE = 0.05;
    public static final double PENNY_VALUE = 0.01;

    private double purchase;
    private double payment;

    /**
     * Constructs a cash register with no money in it.
     */
    public CashRegister() {
        purchase = 0;
        payment = 0;
    }

    /**
     * Records the purchase price of an item.
     * @param amount the price of the purchased item
     */
    public void recordPurchase(double amount) {
        purchase = purchase + amount;
    }

    /**
     * Processes the payment received from the customer.
     * @param dollars the number of dollars in the payment
     * @param quarters the number of quarters in the payment
     * @param dimes the number of dimes in the payment
     * @param nickles the number of nickles in the payment
     * @param pennies the number of pennies in the payment
     */
    public void receivePayment(int dollars, int quarters, int dimes, int nickles, int pennies) {
        payment =
                dollars +
                quarters * QUARTER_VALUE +
                dimes * DIME_VALUE +
                nickles * NICKLE_VALUE +
                pennies * PENNY_VALUE;
    }

    /**
     * Computes the change due and resets the machine for the next customer.
     * @return the change due to the customer
     */
    public double giveChange() {
        double change = payment - purchase;
        purchase = 0;
        payment = 0;
        return change;
    }
}