Super class and Sub class inheritance not working

[Dan D'Apice]

Hello All,
Well, looks like I've got another mess here. Part 3 of the Inventory program requirements are as follows:

- Modify the Inventory Program by creating a subclass of the product class that uses one additional unique attribute of the product you chose (for example, if Movie is your product, you can create a subclass named ForiegnMovie with “country” as a unique attribute).
- In the subclass, override the method to calculate the value of the inventory of a product with the same name and return type as the method previously created for the product class. The subclass override should add a 5% restocking fee to the value of the product.
- Modify the output to display this additional attribute you have chosen and the restocking fee.

This is what I have for code (please be merciful...):

package inventory;
import java.util.ArrayList;
import java.util.Arrays;
/**
 * Inventory Class
 * @author Dan
 * Modified 9/27/2012
 */
public class Inventory {
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        
        /* Create new variable for inventory calculation */
        double total = 0.0;
        
        /* Create new ArrayList */
        ArrayList<Book> bookList;
        bookList = new ArrayList<>();
        
        /* Add elements to ArrayList */
        bookList.add(new Book("001a", "Java 101", 50, 19.99));
        bookList.add(new Book("001b", "C# 101\t", 50, 19.95));
        bookList.add(new Book("001c", "Python 101", 25, 25.99));
        
        /* Print out data from elements in ArrayList */
        System.out.println("Item#\tBook Name\tIn Stock\tPrice Each\tItem Class\tRestock Price*");
        System.out.println(bookList.get(0) );
        System.out.println(bookList.get(1) );
        System.out.println(bookList.get(2) );
        
        /* Calculate total inventory value */
        for (Book list : bookList)
        {
            total += list.gettotal();
        }
        /* Display total inventory value */
        System.out.printf("\nThe total value of the inventory is: $%,.2f\n", total);
        System.out.println();
        System.out.println("* Restock Price reflects a 5 percent restocking fee for entire stock of each specific item.");
        System.out.println();
    } /* End main */
} /* End class */

package inventory;

/**
 * Book Class
 * @author Dan
 * Modified 9/27/2012
 */
public class Book implements Comparable{
    /* Define variables */
    
    protected String itemNumber;
    protected String itemName;
    protected Integer inStock;
    protected Double priceEach;
    
    /* Parameterized Constructor */
    public Book(String itemNumber, String itemName, Integer inStock, Double priceEach)
    {
        this.itemNumber = itemNumber;
        this.itemName = itemName;
        this.inStock = inStock;
        this.priceEach = priceEach;
    }
    
    /* Calculate value of stock */
    public Double gettotal()
    {
        return this.priceEach * this.inStock;
    }
    /* Define Set and Get functions */
    public void setItemNumber()
    {
        itemNumber = itemNumber;
    }
    public String getItemNumber()
    {
        return itemNumber;
    }
    public void setItemName()
    {
        itemName = itemName;
    }
    public String getItemName()
    {
        return itemName;
    }
    public void setInStock()
    {
        inStock = inStock;
    }
    public Integer getInStock()
    {
        return inStock;
    }
    public void setPriceEach()
    {
        priceEach = priceEach;
    }
    public Double getPriceEach()
    {
        return priceEach;
    }
    /* Sort array by name? */
    @Override
    public int compareTo(Object o)
    {
        Book inputParameter = (Book)o;
        return itemName.compareTo(inputParameter.itemName);
    }
    /* Override otString to display array data */
    @Override
    public String toString()
    {
        return String.format(itemNumber + "\t" + itemName + "\t" + inStock + "\t\t" + priceEach);
    }
} /* End class */

package inventory;

/**
 * Subclass of Book
 * @author Dan
 * Created 9/28/2012
 */
public class TrainingBook extends Book{
    /* Declare new variable */
    String itemClass = "Training";
    Double itemTotal = 0.0;
    
    /* Inheret conductor from Book */
    public TrainingBook(String itemNumber, String itemClass, String itemName, Integer inStock, Double priceEach) {
        super(itemNumber, itemName, inStock, priceEach);
        this.itemNumber = itemNumber;
        this.itemName = itemName;
        this.inStock = inStock;
        this.priceEach = priceEach;
        this.itemClass = itemClass;
    }
    
    /* New procedures */
    public void setItemclass()
    {
        itemClass = itemClass;
    }
    public String getItemclass()
    {
        return itemClass;
    }
   
    public void setItemTotal()
    {
        itemTotal = itemTotal;
    }
    
    public Double getitemTotal()
    {
        return (this.priceEach * this.inStock) * 1.05;
    }
    @Override
    public String toString()
    {
        return String.format(itemNumber + "\t" + itemName + "\t" + inStock + "\t\t" + priceEach + "\t" + itemClass + "\t" + itemTotal);
    }
}

OUTPUT:

run:
Item#	Book Name	In Stock	Price Each	Item Class	Restock Price*
001a	Java 101	50		19.99
001b	C# 101		50		19.95
001c	Python 101	25		25.99

The total value of the inventory is: $2,646.75

* Restock Price reflects a 5 percent restocking fee for entire stock of each specific item.

BUILD SUCCESSFUL (total time: 0 seconds)

I'm sure it's something simple I missed, but being a complete novice, I can't see it. Any help would be greatly appreciated...

[Kemal Sokolovic]

I suppose this is the method that calculates mentioned price in your superclass:

public Double gettotal()
{
    return this.priceEach * this.inStock;
}

You didn't override it in your subclass. Instead, you've actually implemented another method:

public Double getitemTotal()
{
    return (this.priceEach * this.inStock) * 1.05;
}

If your intention is to override superclass method in a subclass, overriden method needs to have the same signature as the one in superclass.

Furthermore, I notice that your setters are not implemented correctly. Instead of what you have implemented, each setter in your class should look like this:

public void setItemClass(String itemClass)
{
    this.itemClass = itemClass;
}

Notice that it has an argument of the same type as field you are setting value of. You should also use Camel notation for naming your methods as well as fields (with exception of constants, which you are not using).

Also, your subclass constructor shouldn't look like this:

public TrainingBook(String itemNumber, String itemClass, String itemName, Integer inStock, Double priceEach)
{
    super(itemNumber, itemName, inStock, priceEach);
    this.itemNumber = itemNumber;
    this.itemName = itemName;
    this.inStock = inStock;
    this.priceEach = priceEach;
    this.itemClass = itemClass;
}

Once you invoke superclass constructor, there is no need to set the same fields again, because super has already done that, so what you should set are actually just fields specific to your subclass.

[Dan D'Apice]

Kemal,
Thanks for pointing those things out. The problem I'm having is getting the data in the sub-class back to the Inventory class. I'm at my boiling point right now so I have to step away for a while. Thanks again...

[Tony Docherty]

If you do what Kemal has already suggested it will work.

BTW what's the purpose of the itemClass instance variable which is set to "Training". You know the object is a training book because it's an instance of the TrainingBook class.
If you ever have an instance variable that is hard coded to a value and is never changed then you have a design problem.

[Campbell Ritchie]

Is the return type for those methods really Double? Don’t you mean double?

Actually, you ought never to use double arithmetic for money. Use what is described in this thread: BigDecimal.

[Dan D'Apice]

Update: OK, the code below is almost there. The last thing I need to do is populate "Restock price" with the result of the "(InStock * PriceEach) * 1.05" formula in the TrainingBook class. I need to generate separate instances of Java 101, C#, and Python. Basically I need to have the value of each book with a 5% restocking fee on each "Restock Price" line and I'm done. Any ideas? Do I need to create a for loop for each instance? Maybe a new ArrayList for NewTotal? Not quite sure what to do at this point. Also, I realize the Restock Price is null because it's not set. Code follows:

package inventory;
import java.util.ArrayList;
import java.util.Arrays;
/**
 * Inventory Class
 * @author Dan
 * Modified 9/27/2012
 */
public class Inventory {
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        
        /* Create new variable for inventory calculation */
        double total = 0.0;
        
        /* Create new ArrayList */
        ArrayList<Book> BookList;
        BookList = new ArrayList<>();
        ArrayList<TrainingBook> TrainList;
        TrainList = new ArrayList<>();
        
        /* Add elements to ArrayList */
        BookList.add(new Book("001a", "Java 101", 50, 19.99) );
        BookList.add(new Book("001b", "C# 101\t", 50, 19.95) );
        BookList.add(new Book("001c", "Python 101", 25, 25.99) );
        TrainList.add(new TrainingBook("001a", "Java 101", 50, 19.99, "Training"));
        TrainList.add(new TrainingBook("001b", "C# 101\t", 50, 19.95,"Training"));
        TrainList.add(new TrainingBook("001c", "Python 101", 25, 25.99, "Training"));
        
        /* Print out data from elements in ArrayList */
        System.out.println("Item#\tBook Name\tIn Stock\tPrice Each\tItem Class\tRestock Price*");
        System.out.println(TrainList.get(0) );        
        System.out.println(TrainList.get(1) );
        System.out.println(TrainList.get(2) );
        
        /* Calculate total inventory value */
        for (Book list : BookList)
        {
            total += list.gettotal();
        }
        /* Display total inventory value */
        System.out.printf("\nThe total value of the inventory is: $%,.2f\n", total);
        System.out.println();
        System.out.println("* Restock Price reflects a 5 percent restocking fee for entire stock of each specific item.");
        System.out.println();
    } /* End main */
} /* End class */

package inventory;

/**
 * Book Class
 * @author Dan
 * Modified 9/27/2012
 */
public class Book implements Comparable{
    /* Define variables */
    
    protected String ItemNumber;
    protected String ItemName;
    protected Integer InStock;
    protected Double PriceEach;
    
    /* Parameterized Constructor */
    public Book(String ItemNumber, String ItemName, Integer InStock, Double PriceEach)
    {
        this.ItemNumber = ItemNumber;
        this.ItemName = ItemName;
        this.InStock = InStock;
        this.PriceEach = PriceEach;

    }
    
    /* Calculate value of stock */
    public Double gettotal()
    {
        return this.PriceEach * this.InStock;
    }
    /* Define Set and Get functions */
    public void setItemNumber(String itemNumber)
    {
        ItemNumber = ItemNumber;
    }
    public String getItemNumber()
    {
        return ItemNumber;
    }
    public void setItemName(String itemName)
    {
        ItemName = ItemName;
    }
    public String getItemName()
    {
        return ItemName;
    }
    public void setInStock(Integer inStock)
    {
        InStock = InStock;
    }
    public Integer getInStock()
    {
        return InStock;
    }
    public void setPriceEach(Double priceEach)
    {
        PriceEach = PriceEach;
    }
    public Double getPriceEach()
    {
        return PriceEach;
    }
    
    /* Sort array by name? */
    @Override
    public int compareTo(Object o)
    {
        Book inputParameter = (Book)o;
        return ItemName.compareTo(inputParameter.ItemName);
    }
    /* Override otString to display array data */
    @Override
    public String toString()
    {
        return String.format(ItemNumber + "\t" + ItemName + "\t" + InStock + "\t\t" + PriceEach);
    }
} /* End class */

package inventory;

/**
 * Subclass of Book
 * @author Dan
 * Created 9/28/2012
 */
public class TrainingBook extends Book{
    /* Declare new variables */
     String ItemClass;
     Double NewTotal;
     
    /* Inheret conductor from Book */
    public TrainingBook(String itemNumber, String itemName, Integer inStock, Double priceEach, String itemClass) 
    {
        super(itemNumber, itemName, inStock, priceEach); 
        this.ItemClass = itemClass;
    }
    
    /* New Method for Item Class */
    public void setItemClass(String ItemClass)
    {
        ItemClass = ItemClass;
    }
    public String getItemClass()
    {
        return ItemClass;
    }
    /* Override Calculation from Book */
    @Override
    public Double gettotal()
    {
        return (this.PriceEach * this.InStock) * 1.05;
    }
    
    /* Override toString to format output */
    @Override
    public String toString()
    {
        return String.format(ItemNumber + "\t" + ItemName + "\t" + InStock + "\t\t" + PriceEach + "\t\t" + ItemClass + "\t" + NewTotal);
    }
}

OUTPUT

run:
Item#	Book Name	In Stock	Price Each	Item Class	Restock Price*
001a	Java 101	50		19.99		Training	null
001b	C# 101		50		19.95		Training	null
001c	Python 101	25		25.99		Training	null

The total value of the inventory is: $2,646.75

* Restock Price reflects a 5 percent restocking fee for entire stock of each specific item.

BUILD SUCCESSFUL (total time: 0 seconds)

[Kemal Sokolovic]

If what you wrote is the formula for calculating restock price in your application, you already have it in your gettotal() method. So just change toString() and add that method call at the end of it (instead of NewTotal).

Note that you didn't follow instructions you got here:

Campbell told you about the types you use.

Tony told you about the design.

I told you about setters (those you implemented still don't work as you expect them, since you are assigning value to itself in them) and use of Camel notation.

[Dan D'Apice]

Kemal,
I had a feeling it was something simple I wasn't seeing (again). Thanks again for the assist. Here is what the output looks like:

run:
Item#	Book Name	In Stock	Price Each	Item Class	Restock Price*
001a	Java 101	50		19.99		Training	1049.475
001b	C# 101		50		19.95		Training	1047.375
001c	Python 101	25		25.99		Training	682.2375000000001

The total value of the inventory is: $2,646.75

* Restock Price reflects a 5 percent restocking fee for entire stock of each specific item.

BUILD SUCCESSFUL (total time: 0 seconds)

Now if I can just trim that output to only 2 places after the decimal point to represent a dollars and cents format. Any ideas or suggestions would be appreciated...

[Kemal Sokolovic]

Formatting Numeric Print Output

[Dan D'Apice]

Thanks again, everyone. I apologize for not incorporating the information you all gave me at first. I am going to take what great information has be given to me here and mull it over again and sort out this last hurdle of my program. I promise I wont ask any more questions about this application... :-D

[Kemal Sokolovic]

Dan D'Apice wrote:I promise I wont ask any more questions about this application... :-D

Nobody told you not to ask questions. Discussion on any topic is what this forum is about.

Cheers!