Lab #6 (Exercise 7-2)

Create a Product application that uses inheritance

Due Date: Thursday of Week 2
10 points

In this lab, you'll create a Product application like the one presented in this chapter that uses inheritance. However, you will add an additional kind of product: compact discs. To make this application easier to develop, we'll give you most of the starting classes.

Create a new subclass named CompactDisc

Copy and paste the codes below:

Product class

import java.text.NumberFormat;

public class Product
{
    private String code;
    private String description;
    private double price;
    public static int count = 0;

    public Product()
    {
        code = "";
        description = "";
        price = 0;
    }

    public void setCode(String code)
    {
        this.code = code;
    }

    public String getCode(){
        return code;
    }

    public void setDescription(String description)
    {
        this.description = description;
    }

    public String getDescription()
    {
        return description;
    }

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

    public double getPrice()
    {
        return price;
    }

    public String getFormattedPrice()
    {
        NumberFormat currency = NumberFormat.getCurrencyInstance();
        return currency.format(price);
    }

    public String toString()
    {
        return "Code:        " + code + "\n" +
               "Description: " + description + "\n" +
               "Price:       " + this.getFormattedPrice() + "\n";
    }

    public static int getCount()
    {
        return count;
    }
}

Book class

public class Book extends Product
{
	private String author;

	public Book()
	{
		super();
		author = "";
		count++;
	}

	public void setAuthor(String author)
	{
		this.author = author;
	}

	public String getAuthor(){
		return author;
	}

	public String toString()
	{
		return super.toString() +
			"Author:      " + author + "\n";
	}
}

Software class

public class Software extends Product
{
	private String version;

	public Software()
	{
		super();
		version = "";
		count++;
	}

	public void setVersion(String version)
	{
		this.version = version;
	}

	public String getVersion(){
		return version;
	}

	public String toString()
	{
		return super.toString() +
			"Version:     " + version + "\n";
	}
}

ProductDB class

public class ProductDB
{
    public static Product getProduct(String productCode)
    {
        // In a more realistic application, this code would
        // get the data for the product from a file or database
        // For now, this code just uses if/else statements
        // to return the correct product data

        Product p = null;

        if (productCode.equalsIgnoreCase("java") ||
           productCode.equalsIgnoreCase("jsps") ||
           productCode.equalsIgnoreCase("mcb2"))
        {
            Book b = new Book();
            if (productCode.equalsIgnoreCase("java"))
            {
                b.setCode(productCode);
                b.setDescription("Murach's Beginning Java 2");
                b.setPrice(49.50);
                b.setAuthor("Andrea Steelman");
            }
            else if (productCode.equalsIgnoreCase("jsps"))
            {
                b.setCode(productCode);
                b.setDescription("Murach's Java Servlets and JSP");
                b.setPrice(49.50);
                b.setAuthor("Andrea Steelman");
            }
            else if (productCode.equalsIgnoreCase("mcb2"))
            {
                b.setCode(productCode);
                b.setDescription("Murach's Mainframe COBOL");
                b.setPrice(59.50);
                b.setAuthor("Mike Murach");
            }
            p = b; // set Product object equal to the Book object
        }
        else if (productCode.equalsIgnoreCase("txtp"))
        {
            Software s = new Software();
            s.setCode("txtp");
            s.setDescription("TextPad");
            s.setPrice(27.00);
            s.setVersion("4.7.3");
            p = s; // set Product object equal to the Software object
        }
        return p;
    }
}

ProductApp class

import java.util.Scanner;

public class ProductApp
{
    public static void main(String args[])
    {
        // display a weclome message
        System.out.println("Welcome to the Product Selector\n");

        // perform 1 or more selections
        Scanner sc = new Scanner(System.in);
        String choice = "y";
        while (choice.equalsIgnoreCase("y"))
        {
            System.out.print("Enter product code: ");
            String productCode = sc.next();  // read the product code
            sc.nextLine();  // discard any other data entered on the line

            // get the Product object
            Product p = ProductDB.getProduct(productCode);

            // display the output
            System.out.println();
            if (p != null)
                System.out.println(p.toString());
            else
                System.out.println("No product matches this product code.\n");

            System.out.println("Product count: " + Product.getCount() + "\n");

            // see if the user wants to continue
            System.out.print("Continue? (y/n): ");
            choice = sc.nextLine();
            System.out.println();
        }
    }
}

Add a class named CompactDisc that inherits the Product class. This new class should work like the Book and Software classes, but it should include public get and set methods for a private instance variable named artist. In addition, it should include a toString method that overrides the toString method in the Product class. This method should append the artist name to the end of the string.

Compile the CompactDisc class to make sure that it doesn't contain any syntax errors.

Modify the ProductDB class so it returns a CompactDisc object

Modify the ProductDB class so it creates at least one CompactDisc object. For example, this object might contain the following information:

Cose:        sgtp
Description: Sgt. Pepper's Lonely Hearts Club Band
Price:       $15.00
Artist:      The Beatles

Compile this class and run the application to make sure it works.

Add a protected variable

Open the Product class and change the access modifier for the count varaible from public to protected.

Compile this class, and then run the application one more time to make sure that the count is maintained properly.

Include in your program the following comments:

Name of program
Team's name with all the names of the members (e.g. Team A: John Doe, Jane Smith, etc.)
Current Date
Computer system and compiler you are using
Brief description of the program

Compile and run the Java program.

Take a screen capture by hitting simultaneously the keys Alt and Print Screen (Prt Sc) of the output results (console) and paste it in MS Paint. Save it as a gif file.

When you are ready, upload the java programs by clicking the link below:

Upload Lab

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