Attempting to Call a Method from a Subclass

[pixiedustjt]

Hello,

This is my first time to post on the forum, so I hope I'm doing this correctly. I am working on the dreading Java Inventory Program that seems to be legendary. I am currently on part 3 and have most of the program working. I created an additional feature (book author) in a subclass, which is supposed to be called in my main class and populate my array. I've created the subclass and added the new feature, but can't figure out how to call it in my main class to populate and display in my array. Any tips or advice is greatly appreciated!

I read the guidelines, so I'm a little worried about posting too much code. I've attached a part of my subclass where I created my "new" feature, hoping this is a good starting point and someone can confirm if I set this part up correctly.

Thanks!

public class Book2 extends Book
{
 
    // Book2 variable
    private String bookAuthor; // Author of the book
 
    // Book2 constructor
    public Book2(String bookTitle, int itemNumber, int bookUnits, double bookPrice, String bookAuthor)
    {
 
        // call super class constructor
        super(bookTitle, itemNumber, bookUnits, bookPrice);
 
        this.bookAuthor = bookAuthor; // initializes bookTitle for Book2
    } // end constructor
 
    // method to set the book author
    public void setBookAuthor (String bookAuthor)
    {
        this.bookAuthor = bookAuthor;
    } // end method setBookAuthor
 
    // method to retrieve the book author
    public String getBookAuthor()
    {
        return bookAuthor;
    } // end method getBookAuthor

[JosAH]

That class looks fine to me; personally I wouldn't have included that setBookAuthor
method because it would be silly for a book being written by X suddenly has been
written by Y. I don't see any other problems. Simply use Book2 references in
you main method and that's it.

kind regards,

Jos

[praveen2gupta]

Hello,

This is my first time to post on the forum, so I hope I'm doing this correctly. I am working on the dreading Java Inventory Program that seems to be legendary. I am currently on part 3 and have most of the program working. I created an additional feature (book author) in a subclass, which is supposed to be called in my main class and populate my array. I've created the subclass and added the new feature, but can't figure out how to call it in my main class to populate and display in my array. Any tips or advice is greatly appreciated!

I read the guidelines, so I'm a little worried about posting too much code. I've attached a part of my subclass where I created my "new" feature, hoping this is a good starting point and someone can confirm if I set this part up correctly.

Thanks!

public class Book2 extends Book
{
 
    // Book2 variable
    private String bookAuthor; // Author of the book
 
    // Book2 constructor
    public Book2(String bookTitle, int itemNumber, int bookUnits, double bookPrice, String bookAuthor)
    {
 
        // call super class constructor
        super(bookTitle, itemNumber, bookUnits, bookPrice);
 
        this.bookAuthor = bookAuthor; // initializes bookTitle for Book2
    } // end constructor
 
    // method to set the book author
    public void setBookAuthor (String bookAuthor)
    {
        this.bookAuthor = bookAuthor;
    } // end method setBookAuthor
 
    // method to retrieve the book author
    public String getBookAuthor()
    {
        return bookAuthor;
    } // end method getBookAuthor

Hi
your code is correct and i see that there is no problem in the calling super class constructor. You should create object of class Book2 and call the methods getBookAuthor().

[pixiedustjt]

Hello,

Thank you so much for the feedback, it's good to know that my subclass is ok. What I'm having problems with is creating object of class Book2 and calling the getBookAuthor().

When I attempt to compile my main file, I get the following 7 errors:
C:\java>javac Inventory_Program3.java
Inventory_Program3.java:48: cannot find symbol
symbol : constructor Book(java.lang.String,int,int,double,java.lang.Str ing)
location: class Book
myBook[0] = new Book("The Key Triology", 1, 25, 7.99, "Nora Robe
rts");
^
Inventory_Program3.java:49: cannot find symbol
symbol : constructor Book(java.lang.String,int,int,double,java.lang.Str ing)
location: class Book
myBook[1] = new Book("The Shinning", 2, 15, 5.99, "Steven King")
;
^
Inventory_Program3.java:50: cannot find symbol
symbol : constructor Book(java.lang.String,int,int,double,java.lang.Str ing)
location: class Book
myBook[2] = new Book("Wild Acre", 3, 7, 4.99, "Phillipa Gregory"
);
^
Inventory_Program3.java:51: cannot find symbol
symbol : constructor Book(java.lang.String,int,int,double,java.lang.Str ing)
location: class Book
myBook[3] = new Book("Dark Paradise", 4, 2, 12.99, "Tami Hoag");

^
Inventory_Program3.java:52: cannot find symbol
symbol : constructor Book(java.lang.String,int,int,double,java.lang.Str ing)
location: class Book
myBook[4] = new Book("Dollhouse Murders", 5, 18, 2.95, "Betty Re
n Wright");
^
Inventory_Program3.java:56: cannot find symbol
symbol : constructor Book2()
location: class Book2
Book2 author = new Book2();
^
Inventory_Program3.java:80: cannot find symbol
symbol : method getBookAuthor()
location: class Book
System.out.println("The book author is: " + myBook[i].ge
tBookAuthor());
^
7 errors

Here is some of my code from my main class:

public class Inventory_Program3
{
 
    // Declare an array of classes
    private Book myBook[];    
 
    // method to sort inventory by book title
    public Book[] sortBookInventory()
        {
            for(int i = 0; i < myBook.length; i++) 
        {
                String bookTitle1 = myBook[i].getBookTitle();
                int min = i;
                String bookTitle = bookTitle1;
                    for(int j = i+1; j < myBook.length; j++) 
            {
                    String bookTitle2 = myBook[j].getBookTitle();
                        if(bookTitle2.compareTo(bookTitle) < 0) 
                {
                            min = j;
                            bookTitle = bookTitle2;
                        }
                    }
                if(!bookTitle.equals(bookTitle1)) 
        {
                    Book temp = myBook[i];
                    myBook[i] = myBook[min];
                    myBook[min] = temp;
               }
            }
                return myBook;
    } // end method sortBookInventory
 
    // constructor
    Inventory_Program3()
    {
 
        double totalInventoryValue = 0.0;
 
 
        // Specify how many items are in the array
        myBook = new Book[5];
        myBook[0] = new Book("The Key Triology", 1, 25, 7.99, "Nora Roberts");
        myBook[1] = new Book("The Shinning", 2, 15, 5.99, "Steven King");
        myBook[2] = new Book("Wild Acre", 3, 7, 4.99, "Phillipa Gregory");
        myBook[3] = new Book("Dark Paradise", 4, 2, 12.99, "Tami Hoag");
        myBook[4] = new Book("Dollhouse Murders", 5, 18, 2.95, "Betty Ren Wright");
 
 
        // instantiate Book2 object
        Book2 author = new Book2();
 
        // call method sort book inventory for display
        sortBookInventory();
 
        for (int i = 0; i<5; i++)
        {
 
            // display the book title
            System.out.println("The book title is: " + myBook[i].getBookTitle());
 
            // display the item number
            System.out.println("The item number is: " + myBook[i].getItemNumber());
 
            // display the number of units in stock
            System.out.println("The number of units in stock is: " + myBook[i].getBookUnits());
 
            // display the price per book
            System.out.printf("The price of the book is: $%.2f\n", myBook[i].getBookPrice());
 
            // display the value of the inventory
            System.out.printf("The value of the inventory is: $%.2f\n", myBook[i].inventoryValue());
 
            // display the book author
            System.out.println("The book author is: " + myBook[i].getBookAuthor());

[r035198x]

Perhaps you wanted to create Book2 objects instead of Book objects.
The constructors you are calling are in Book2 not in Book.

[pixiedustjt]

Oh my gosh - PERFECT!!!!!! Thank you so much!!!!!! IT WORKED!!!!!!!!!!!!!!!! Two days of hacking away and it worked!!!!!!