Super & Sub Classes

Question

this is my application class where i have instead array of objects
loanBook is a super class and loanDocumentry is a sub class that extends loanBook. This is declared at the top of the application class

public static loanBook[] bookArray = new loanDocumetry[5];

then in my application class i have to add new documentry book so i use the scanner for inputs and then use them to add the new object

bookArray[i] = new loanDocumentry(
    title, author, publisher, year, noOfPages, genre);

and the book count in loanBook increases so I know each time I run the method it creates new book but when then printing the array out it looks like it never added any of those books to the array and that the only one i have added is the last one

Application Class:

public class ApplicationClass {

public static Scanner input = new Scanner(System.in);
public static loanBook[] bookArray = new loanDocumentry[5];

public static void main(String[] args) {
    addBook();
}

public static void addBook() {
    input.nextLine();

    String title;
    String author;
    String publisher;
    int year;
    int noOfPages;
    String genre;
    String choice;
    int i = 0;


            System.out.print("\nTITLE of the book: ");
            title = input.nextLine();
            System.out.print("AUTHOR of the book: ");
            author = input.nextLine();
            System.out.print("PUBLISHER of the book: ");
            publisher = input.nextLine();
            System.out.print("YEAR book was published in: ");
            year = input.nextInt();
            System.out.print("NUMBER OF PAGES the book has: ");
            noOfPages = input.nextInt();
            System.out.print("GENRE of the book: ");
            input.nextLine();
            genre = input.nextLine();
            bookArray[i] = new loanDocuemntry(title, author, publisher, year, noOfPages, genre);
            i++;

}

loanBook Superclass & loanDocumentry Sub class both use set and gets

its a very long code that has 4 different java files and its menu driven there is a lot of print statments etc — user3057408, Dec 02 '13 at 19:47
Related material: http://stackoverflow.com/questions/12878879/subtype-polymorphism-and-arrays Also try removing static from the declaration. — ryanlutgen, Dec 02 '13 at 19:47
Try to make a [SSCCE](http://sscce.org), then you isolate the problem and it will easier for you and for us if you still need help . — nachokk, Dec 02 '13 at 19:57

score 0 · Accepted Answer · answered Dec 02 '13 at 19:57

0

Try doing a print on i from the line above bookArray[i] = new loanDocumenry( It should be changing while each new loanBook is added.

When you add a loanBook, i should be increased by 1 so you are setting bookArray[0], bookArray[1], bookArray[2], bookArray[3], bookArray[4]. You are only setting the first one.

answered Dec 02 '13 at 19:57

DoubleDouble

1,493
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it is increased by one – user3057408 Dec 02 '13 at 20:02
Yes, in your method, you set it to 0. Then at the end you increase it to 1. But, when you add your next book it starts at 0 again, and increases to 1 again. adding static to a method does not keep int `i` at the same value it was before. – DoubleDouble Dec 02 '13 at 20:07
How can I amend this ? – user3057408 Dec 02 '13 at 20:08
If I have I outside of the method will that help – user3057408 Dec 02 '13 at 20:09
Easiest way is to move `i` somewhere above the method where the method will have access to it. – DoubleDouble Dec 02 '13 at 20:10
If you'd like more information on instance vs. class variables, check out this [link](http://docs.oracle.com/javase/tutorial/java/javaOO/classvars.html). – DoubleDouble Dec 02 '13 at 20:14
no it was mistake made it makes sence where i went wrong its just i only started to test the application and see those problems - thanks for help though – user3057408 Dec 02 '13 at 20:30

Super & Sub Classes

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