Array List is Printing Out the Exact Same Thing

public class Book { static String title; static boolean borrowed; public Book(String bookTitle){ // Creates a new Book title = bookTitle; } public static boolean borrowed() { // Marks the book as borrowed borrowed = true; return borrowed; } // Marks the book as available, i.e., not borrowed public static boolean returned() { borrowed = false; return borrowed; } // Returns true if the book is borrowed, false otherwise public boolean isBorrowed() { return borrowed; } // Returns the title of the book public static String getTitle() { return title; } public static void main(String[] arguments){ // Small test of the Book class Book example = new Book("The Da Vinci Code"); System.out.println("Title (should be The Da Vinci Code): " + example.getTitle()); System.out.println("Borrowed? (should be false): " + example.isBorrowed()); example.borrowed(); System.out.println("Borrowed? (should be true): " + example.isBorrowed()); example.returned(); System.out.println("Borrowed? (should be false): " + example.isBorrowed()); } }

public class Library { Book[] books = new Book[20];; int numBooks = 0; String address; static String hours; void addBook(String bookTitle) { //This where I am having trouble populating my array books[numBooks] = new Book(bookTitle); ++numBooks; } /* public boolean borrowBook(String title) { //Marks the book as borrowed if (Book.title == Book.getTitle()){ Book.borrowed = true;} //refers to a method in another class I created return Book.borrowed; } public boolean returnBook(String title) { //Marks the book as returned if (Book.title == Book.getTitle()){ Book.borrowed = false; }//refers to a method in another class I created return Book.borrowed; } */ public Library(String street) { //creates new street address street = address; } public String printAddress() { //returns the street address when referenced return address; } void printAvailableBooks() { //supposed take a book out of the list if borrowed for(int i = 0; i < numBooks; i++) { System.out.println(books[i].getTitle()); } } static String printOpeningHours() { hours = "We are open from 9-5."; return hours; } public static void main(String[] args){ Library firstLibrary = new Library("10 Main St."); // Create two libraries Library secondLibrary = new Library("228 Liberty St."); firstLibrary.addBook("The Da Vinci Code");// This is where I am getting my exception firstLibrary.addBook("Le Petit Prince"); firstLibrary.addBook("A Tale of Two Cities"); firstLibrary.addBook("The Lord of the Rings"); System.out.println("Library hours:"); // Print opening hours and the addresses printOpeningHours(); System.out.println(hours); System.out.println("Library addresses:"); firstLibrary.printAddress(); secondLibrary.printAddress(); // Try to borrow The Lords of the Rings from both libraries /* System.out.println("Borrowing The Lord of the Rings:"); firstLibrary.borrowBook("The Lord of the Rings"); firstLibrary.borrowBook("The Lord of the Rings"); secondLibrary.borrowBook("The Lord of the Rings"); */ // Print the titles of all available books from both libraries System.out.println("Books available in the first library:"); firstLibrary.printAvailableBooks(); System.out.println("Books available in the second library:"); secondLibrary.printAvailableBooks(); // Return The Lords of the Rings to the first library /* System.out.println("Returning The Lord of the Rings:"); firstLibrary.returnBook("The Lord of the Rings"); */ // Print the titles of available from the first library System.out.println("Books available in the first library:"); firstLibrary.printAvailableBooks(); } }

My problem is that whenever I run this everything runs fine. Except when I print the avalible books, it prints the exact same book 4 times. I know that it creates an array, because it prints out four times. However, I can't figure out why it prints out the last book added only.

No, there are four books in your example. Your problem is not that, your problem is that each book should have its own title and its own "borrowed" flag. But your Book class doesn't work like that. I will just give you a hint that the problem is with the declaration of those two fields.

Thanks a lot Phil. I got my code up and running and works fine. I am having a weird error. I put the firstLibrary.printAddress() into System.out.println() and it is printing out null. I was looking at the structure of my Book class for getTitle() and the Book constructor and it is the exact same structure.

Brian Wimpsett wrote:I am having a weird error. I put the firstLibrary.printAddress() into System.out.println() and it is printing out null. I was looking at the structure of my Book class for getTitle() and the Book constructor and it is the exact same structure.

Well, a good place to look is at the constructor...

public Library(String street) { //creates new street address street = address; }

Care to explain what you are trying to do?

Henry

Sure, I am trying to set the value of address to the argument in the constructor.

Brian Wimpsett wrote:Sure, I am trying to set the value of address to the argument in the constructor.

Are you sure?

Never mind. I had the values reversed. it should be address = street Thanks anyway.