Solutions to the Try It Out Exercises in Java For Dummies, 8th Edition
by Barry Burd

Chapter 8: Saving Time and Money: Reusing Existing Code

In this chapter:

Locale, Locale, Locale

public class PlaceToLive {
  private String address;
  private int numberOfBedrooms;
  private double area;

  public String getAddress() {
    return address;
  }

  public void setAddress(String address) {
    this.address = address;
  }

  public int getNumberOfBedrooms() {
    return numberOfBedrooms;
  }

  public void setNumberOfBedrooms(int numberOfBedrooms) {
    this.numberOfBedrooms = numberOfBedrooms;
  }

  public double getArea() {
    return area;
  }

  public void setArea(double area) {
    this.area = area;
  }
}

import java.util.Scanner;

public class DisplayThePlaces {

  public static void main(String[] args) {
    var keyboard = new Scanner(System.in);

    var place1 = new PlaceToLive();
    place1.setAddress("111 Main Street");
    place1.setArea(600);
    place1.setNumberOfBedrooms(2);
    System.out.print("Cost of " + place1.getAddress() + ": ");
    double cost1 = keyboard.nextDouble();

    var place2 = new PlaceToLive();
    place2.setAddress("222 Java Road");
    place2.setArea(1000);
    place2.setNumberOfBedrooms(1);
    System.out.print("Cost of " + place2.getAddress() + ": ");
    double cost2 = keyboard.nextDouble();

    System.out.println(place1.getAddress());
    System.out.println
      ("  Cost per unit area: " + cost1 / place1.getArea());
    System.out.println
      ("  Cost per bedroom:   " + cost1/ place1.getNumberOfBedrooms());

    System.out.println(place2.getAddress());
    System.out.println
      ("  Cost per unit area: " + cost2 / place2.getArea());
    System.out.println
      ("  Cost per bedroom:   " + cost2 / place2.getNumberOfBedrooms());

    keyboard.close();
  }
}

Pay Per Click

public class PlaceToLive {
  private String address;
  private int numberOfBedrooms;
  private double area;

  public String getAddress() {
    return address;
  }

  public void setAddress(String address) {
    this.address = address;
  }

  public int getNumberOfBedrooms() {
    return numberOfBedrooms;
  }

  public void setNumberOfBedrooms(int numberOfBedrooms) {
    this.numberOfBedrooms = numberOfBedrooms;
  }

  public double getArea() {
    return area;
  }

  public void setArea(double area) {
    this.area = area;
  }
}


import com.allmycode.dummiesframe.DummiesFrame;

public class Main {

    public static void main(String[] args) {
        var frame = new DummiesFrame("Place to Live");
        frame.addRow("Address");
        frame.addRow("Area");
        frame.addRow("Number of Bedrooms");
        frame.addRow("Cost");
        frame.setButtonText("Display");
        frame.go();
    }

    public static String calculate(String address,
                                   double area,
                                   int numberOfBedrooms,
                                   double cost) {

        var place = new PlaceToLive();
        place.setAddress(address);
        place.setArea(area);
        place.setNumberOfBedrooms(numberOfBedrooms);

        return address + "; " +
               "Cost per unit area: " + (cost / place.getArea()) + "; " +
               "Cost per bedroom: " +
                                     (cost / place.getNumberOfBedrooms());
    }
}

On the Record

public class PlaceToLive {
  private String address;
  private int numberOfBedrooms;
  private double area;

  public String getAddress() {
    return address;
  }

  public void setAddress(String address) {
    this.address = address;
  }

  public int getNumberOfBedrooms() {
    return numberOfBedrooms;
  }

  public void setNumberOfBedrooms(int numberOfBedrooms) {
    this.numberOfBedrooms = numberOfBedrooms;
  }

  public double getArea() {
    return area;
  }

  public void setArea(double area) {
    this.area = area;
  }
}


import java.io.File;
import java.io.IOException;
import java.util.Scanner;

public class DisplayThePlaces {

  public static void main(String[] args) throws IOException {
    var diskScanner = new Scanner(new File("places.txt"));
    var keyboard = new Scanner(System.in);

    var place1 = new PlaceToLive();
    place1.setAddress(diskScanner.nextLine());
    place1.setArea(diskScanner.nextDouble());
    place1.setNumberOfBedrooms(diskScanner.nextInt());
    System.out.print("Cost of " + place1.getAddress() + ": ");
    double cost1 = keyboard.nextDouble();

    diskScanner.nextLine();

    var place2 = new PlaceToLive();
    place2.setAddress(diskScanner.nextLine());
    place2.setArea(diskScanner.nextDouble());
    place2.setNumberOfBedrooms(diskScanner.nextInt());
    System.out.print("Cost of " + place2.getAddress() + ": ");
    double cost2 = keyboard.nextDouble();

    System.out.println(place1.getAddress());
    System.out.println
      ("  Cost per unit area: " + cost1 / place1.getArea());
    System.out.println
      ("  Cost per bedroom:   " + cost1/ place1.getNumberOfBedrooms());

    System.out.println(place2.getAddress());
    System.out.println
      ("  Cost per unit area: " + cost2 / place2.getArea());
    System.out.println
      ("  Cost per bedroom:   " + cost2 / place2.getNumberOfBedrooms());

    diskScanner.close();
    keyboard.close();
  }
}
Here's a sample places.txt file: 
111 Main Street
1000
2
222 Java Row
1200
3

Buy or Rent

public class PlaceToLive {
  private String address;
  private int numberOfBedrooms;
  private double area;

  public String getAddress() {
    return address;
  }

  public void setAddress(String address) {
    this.address = address;
  }

  public int getNumberOfBedrooms() {
    return numberOfBedrooms;
  }

  public void setNumberOfBedrooms(int numberOfBedrooms) {
    this.numberOfBedrooms = numberOfBedrooms;
  }

  public double getArea() {
    return area;
  }

  public void setArea(double area) {
    this.area = area;
  }
}

public class House extends PlaceToLive {
  private double mortgage;
  private double propertyTax;

  public double getMortgage() {
    return mortgage;
  }

  public void setMortgage(double mortgage) {
    this.mortgage = mortgage;
  }

  public double getPropertyTax() {
    return propertyTax;
  }

  public void setPropertyTax(double propertyTax) {
    this.propertyTax = propertyTax;
  }

  public double getTotalMonthlyPayment() {
    return mortgage + propertyTax / 12;
  }
}

public class Apartment extends PlaceToLive {
  private double rent;

  public double getRent() {
    return rent;
  }

  public void setRent(double rent) {
    this.rent = rent;
  }
}


public class DisplayThePlaces {

  public static void main(String[] args) {
    var place1 = new House();
    place1.setAddress("111 Main Street");
    place1.setArea(600);
    place1.setNumberOfBedrooms(2);
    place1.setMortgage(1000.00);
    place1.setPropertyTax(600);
    double cost1 = place1.getTotalMonthlyPayment();

    var place2 = new Apartment();
    place2.setAddress("222 Java Road");
    place2.setArea(1000);
    place2.setNumberOfBedrooms(1);
    place2.setRent(1500);
    double cost2 = place2.getRent();

    System.out.println(place1.getAddress());
    System.out.println
      ("  Cost per unit area: " + cost1 / place1.getArea());
    System.out.println
      ("  Cost per bedroom:   " + cost1/ place1.getNumberOfBedrooms());

    System.out.println(place2.getAddress());
    System.out.println
      ("  Cost per unit area: " + cost2 / place2.getArea());
    System.out.println
      ("  Cost per bedroom:   " + cost2 / place2.getNumberOfBedrooms());
  }
}

Tax Breaks

public class Organization_2 {
  private String name;
  private double revenue;

  public String getName() {
    return name;
  }

  public void setName(String name) {
    if (!name.equals("")) {
      this.name = name;
    }
  }

  public double getRevenue() {
    return revenue;
  }

  public void setRevenue(double revenue) {
    if (revenue >= 0) {
      this.revenue = revenue;
    }
  }
}

public class ProfitMakingOrganization extends Organization_2 {

  public double getTax() {
    return getRevenue() * 0.10;
  }
}

public class NonProfitOrganization extends Organization_2 {

  public double getTax() {
    return getRevenue() * 0.02;
  }
}


public class Main {

  public static void main(String[] args) {
    var org1 = new ProfitMakingOrganization();
    org1.setName("XYZ Company");
    org1.setRevenue(1000000.00);

    var org2 = new NonProfitOrganization();
    org2.setName("XYZ University");
    org2.setRevenue(100000.00);

    System.out.print(org1.getName());
    System.out.print(" has annual revenue ");
    System.out.print(org1.getRevenue());
    System.out.print(" and pays ");
    System.out.print(org1.getTax());
    System.out.println(" in taxes.");

    System.out.print(org2.getName());
    System.out.print(" has annual revenue ");
    System.out.print(org2.getRevenue());
    System.out.print(" and pays ");
    System.out.print(org2.getTax());
    System.out.println(" in taxes.");
  }

}

Pay More and More

public class ApartmentWithFees extends Apartment{
  private double fees;

  public double getFees() {
    return fees;
  }

  public void setFees(double fees) {
    this.fees = fees;
  }

  public double getTotalMonthlyPayment() {
    return getRent() + fees / 3;
  }
}


public class DisplayThePlaces {

  public static void main(String[] args) {
    var place1 = new House();
    place1.setAddress("111 Main Street");
    place1.setArea(600);
    place1.setNumberOfBedrooms(2);
    place1.setMortgage(1000.00);
    place1.setPropertyTax(600);
    double cost1 = place1.getTotalMonthlyPayment();

    var place2 = new Apartment();
    place2.setAddress("222 Java Road");
    place2.setArea(1000);
    place2.setNumberOfBedrooms(1);
    place2.setRent(1500);
    double cost2 = place2.getRent();

    var place3 = new ApartmentWithFees();
    place3.setAddress("333 Front Street");
    place3.setArea(1500);
    place3.setNumberOfBedrooms(2);
    place3.setRent(700);
    place3.setFees(300);
    double cost3 = place3.getTotalMonthlyPayment();

    System.out.println(place1.getAddress());
    System.out.println("  Montly cost: " + cost1);

    System.out.println(place2.getAddress());
    System.out.println("  Montly cost: " + cost2);

    System.out.println(place3.getAddress());
    System.out.println("  Montly cost: " + cost3);
  }
}

Virtual Methods

The output is 
in MySUBThing, value is 7
In MyOTHERThing, value is 44
So if you have the following declarations: 
MyThing myThing, myThing2;

myThing = new MySubThing();
myThing2 = new MyOtherThing();
and you declare display methods in the MyThing, MySubThing, and MyOtherThing classes, Java calls the display methods that you declared in the MySubThing and MyOtherThing classes. Even though you've declared the myThing and myThing2 variables to be of type MyThing, Java doesn't call the display method that's declared in the MyThing class.