Problem Solving with Algorithms and Data Structures using Java: The Interactive Edition

public class Deck {
    private Card[] cards;
    ...
}

public PowerSupply(int voltage) {
    if (voltage == 220) {
        this.voltage = voltage;
    } else {
        this.voltage = 110;
    }

    // new power supplies are always turned off
    this.turnedOn = false;
}

public Dial(int minValue, int maxValue) {
    this.minValue = minValue;
    this.maxValue = maxValue;
    // new dials are always set to lowest value
    this.dialValue = minValue;
}

class Toaster {
    private int nSlots;
    private int nSlices;
    private PowerSupply power;
    private Dial darkness;

    public Toaster(int nSlots, int voltage) {
        this.nSlots = Math.max(1, Math.min(4, nSlots));
        this.nSlices = 0;
        this.power = new PowerSupply(voltage);
        this.darkness = new Dial(1, 10);
    }
    // ...
}

public boolean isTurnedOn() {
    return this.power.isTurnedOn();
}

public void setTurnedOn(boolean turnedOn) {
    this.power.setTurnedOn(turnedOn);
}

public double getDialValue() {
    return this.darkness.getDialValue();
}

public void setDialValue(double dialValue) {
    this.darkness.setDialValue(dialValue);
}

public class ToasterTest {
    public static void main(String[] args) {
        Toaster euroFour = new Toaster(4, 220);

        euroFour.setTurnedOn(true);
        euroFour.setDialValue(4.5);
        euroFour.insertBread(1);

        System.out.println(euroFour);
    }
}

public class Item {
    private String name;
    private String sku;
    private double price;

    public Item(String name, String sku, double price)  {
        this.name = name;
        this.sku = sku;
        this.price = Math.abs(price);
    }

    public String getName() {
        return this.name;
    }

    public String getSku() {
        return this.sku;
    }

    public double getPrice() {
        return this.price;
    }

    public void setPrice(double price) {
        this.price = Math.abs(price);
    }

    public double purchase(int quantity) {
        return this.price * quantity;
    }

    public String toString() {
        return String.format("%s (%s): $%.2f", this.name,
            this.sku, this.price);
    }

    public boolean equals(Item other) {
        return (this.name.equals(other.name) &&
            this.sku.equals(other.sku) &&
            this.price == other.price);
    }
}

public class SaleItem extends Item {
    private double discount; // as a decimal

    public SaleItem(String name, String sku, double price,
       double discount)  {
       this.name = name;
       this.sku = sku;
       this.price = Math.abs(price);
       this.discount = Math.max(0,
           Math.min(discount, 1.00));
    }
}

public class SaleItem extends Item {
    private double discount; // as a decimal

    public SaleItem(String name, String sku, double price,
       double discount)  {
       super(name, sku, price);
       this.discount = Math.max(0,
           Math.min(discount, 1.00));
    }
}

    public double getDiscount() {
        return this.discount;
    }

    public void setDiscount(double discount) {
        this.discount =
            Math.max(0, Math.min(discount, 1.00));
    }

    public double purchase(int quantity) {
        return (this.getPrice() * quantity) *
            (1 - discount);
    }

    public String toString() {
        return String.format("%s (%s): $%.2f - %.1f%% discount",
            this.getName(), this.getSku(), this.getPrice(),
            this.discount * 100.0);
    }

    public boolean equals(SaleItem other) {
        return (this.getName().equals(other.getName()) &&
            this.getSku().equals(other.getSku()) &&
            this.getPrice() == other.getPrice() &&
            this.discount == other.discount);
    }
}

public class ItemTest {

    public static void main(String[] args) {
        Item envelopes = new Item(
            "Letter Size Envelopes - 100 count",
            "LSE-0100", 5.75);
        SaleItem marker = new SaleItem(
            "Erasable marker - black", "EMB-913",
            2.15, 0.10);

        System.out.println(envelopes);
        double envelopeTotal = envelopes.purchase(10);
        System.out.printf("Ten boxes of envelopes cost $%.2f\n",
            envelopeTotal);

        System.out.println(marker);
        double markerTotal = marker.purchase(10);
        System.out.printf("Ten markers cost $%.2f\n",
            markerTotal);
    }
}

public double purchase(int quantity) {
    return super.purchase(quantity) *
        (1 - discount / 100.0);
}

public String toString() {
    return String.format("%s - %.1f%% discount",
        super.toString(),
        this.discount * 100.0);
}

public boolean equals(SaleItem other) {
    return (super.equals(other) &&
        this.discount == other.discount);
}