Question

Programming language to be used: Java

Exercises

Part 1) The Dog Class

In the first part of the lab, we are writing a class to represent a Dog. It should not have a main method.

1. Dog needs fields for price (to purchase the dog), breed, name, and age. Use appropriate data types
2. The class should have the following two kinds of Constructors:
   1. Constructor 1: Write a constructor that accepts a value for each of the fields
   2. Constructor 2: Write a constructor that accepts no arguments and sets default values of your choice
3. The Dog class requires:
   1. Setters and getters for all fields
   2. A toString() method, which
      1. Returns String
      2. Returns a String describing the dog, such as

Sebastian the Husky is 5 years old.
$45.56 adoption fee

3. Please note that the dollars must be formatted that way

Part 2) The Sales Class

In the second part of the lab, we are writing a class to represent the buying of a Dog or multiple Dogs. Let’s not consider the logistics of buying Dogs in bulk.

1. The Sales class has the following fields – a PrintWriter for a file being used (as well as any other fields you decide you want to help with that) and a double holding the total price of dogs purchased
2. A Sales class has one constructor – it should take a file name to save the output to
3. The Sales class needs the following functions
   1. An addDog method, which saves a new dog to the file (using the toString to get the String representation) and adds the price to the total double
   2. A finalizeReport method, which closes the file after adding a bottom line (“----“) and printing the total price below that line, properly formatted

Part 3) The DogMarket Class

This class should get a file name from the user. It should use the file to create a Sales class object. Then, it should prompt the user for details of the dogs they want to buy. Use a while loop, which uses the word “quit” to not buy a dog and the word “buy” to buy a dog – other words should be ignored, but should not quit the program. If the user says “buy”, ask them for all of the dog’s info, then make a new Dog object and save it to the file using the Sales object. Once the user is done buying dogs, the program should exit, being sure to use finalizeReport() on the sales object

Answer 1

//Dog.java
public class Dog {

   private double price;
   private String breed;
   private String name;
   private int age;
  
// default constructor
   public Dog()
   {
       price = 45.56;
       breed= "Husky";
       name = "Sebastian";
       age = 5;
   }
  
   //parameterized constructor
   public Dog(String name, String breed, double price, int age)
   {
       this.name = name;
       this.breed = breed;
       this.price = price;
       this.age = age;
   }
  
   // setters
   public void setName(String name)
   {
       this.name = name;
   }
  
   public void setBreed(String breed)
   {
       this.breed = breed;
   }
  
   public void setPrice(double price)
   {
       this.price = price;
   }
  
   public void setAge(int age)
   {
       this.age = age;
   }
  
   // getters
   public String getName()
   {
       return name;
   }
  
   public String getBreed()
   {
       return breed;
   }
  
   public double getPrice()
   {
       return price;
   }
  
   public int getAge()
   {
       return age;
   }
  
   //toString
   public String toString()
   {
       return(name+" the "+breed+" is "+age+" years old.\n"+"$"+String.format("%.2f",price)+" adoption fee");
   }
}
//end of Dog.java

//Sales.java
import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintWriter;

public class Sales {
  
   private PrintWriter writer;
   private double totalPrice;
  
   // constructor
   public Sales(String filename) throws FileNotFoundException
   {
       writer = new PrintWriter(new File(filename));
       totalPrice = 0;
   }
  
   // method to add dog details in file and add the price of dog to total price
   public void addDog(Dog dog)
   {
       writer.write(dog.toString()+"\n");
       totalPrice += dog.getPrice();
   }

   // output the total price to file and close the file
   public void finalizeReport()
   {
       writer.write("----\n");
       writer.write("Total price : $"+String.format("%.2f", totalPrice));
       writer.close();
   }
}
//end of Sales.java

// DogMarket.java
import java.io.FileNotFoundException;
import java.util.Scanner;

public class DogMarket {

   public static void main(String[] args) throws FileNotFoundException {
      
       Scanner scan = new Scanner(System.in);
       String filename;
       String command, name, breed;
       double price;
       int age;
       // input the filename
       System.out.print("Enter the output filename : ");
       filename = scan.next();
       scan.nextLine();
       Sales sales = new Sales(filename); // create a Sales object
       // loop that continues till the user quits
       do {
           System.out.println("Buy or Quit ");
           System.out.print("Enter your choice (buy or quit) : ");
           command = scan.nextLine();
          
           // if user selects to buy a dog, input details of Dog and add the dog to Sales object
           if(command.equalsIgnoreCase("buy"))
           {
               System.out.print("Name of the Dog : ");
               name = scan.nextLine();
               System.out.print("Breed of the Dog : ");
               breed = scan.nextLine();
               System.out.print("Enter age of the Dog : ");
               age = scan.nextInt();
               scan.nextLine();
               System.out.print("Enter the price of the Dog : ");
               price = scan.nextDouble();
               scan.nextLine();
               sales.addDog(new Dog(name,breed,price, age));
           }
       }while(!command.equalsIgnoreCase("quit"));
      
       sales.finalizeReport(); // once user quits, call finalize report
       scan.close();
      
   }

}
//end of DogMarket.java

Output:

Output file: