Creating iterative variables through a loop

I am new to Java and am learning classes and objects.

I am making a book library as a practise exercise. I want to get the user to input data for a book using Scanner. I am aware I do not have a while loop in place but I would like to sort the code out for adding 1 book before I do that.

Currently I am stuck on how to iterate through and add multiple books. For example if the user choses to add a book I am assuming it should add books like book1name= Booklist.name. And for when the user wants to add another book I’m assuming it should be book2name= Booklist.name. However I am struggling on how to iterate through this (change it from book1name to book2name automatically) and how to change the variable name while the code is running.

import java.util.Scanner;

public class BookLibrary {
    int counter=1;
    public static void main (String[]args) {
        Scanner choiceScan=new Scanner(System.in);
        System.out.println("Do you want to 1:Add a book or 2:Remove a book");       
        int choice= choiceScan.nextInt();
        if (choice==1) {
            System.out.println("You want to add a book");
            addBook();
        }
        
    }
    public static void addBook() {
        Scanner entryScan=new Scanner(System.in);
        System.out.println("Enter the Name of the book");
        String name=entryScan.nextLine();
        System.out.println("Enter the Author of the book");
        String author=entryScan.nextLine();
        
    }   
}

public class BookList {
    String name;
    String author;
    int bookNum;
    
    public BookList(){
        
    }
    
    public void printLibrary() {
        System.out.println("Book name: "+name );
        System.out.println("Author: " +author);
        System.out.println("Book Number: "+bookNum);
    }
    
    
}

>Solution :

Normally you wouldn’t change dynamically variable names. I think this is first a conceptual error rather than a coding issue.

Java provides several pre-made data structures, such as Maps, Sets, and Lists (this is what you need).

You shouldn’t need to create a BookList object. Instead you should create a Book class, and then instantiate a List of type Book.

I made some basic changes to your code including also some extra suggestions:

1. Renamed BookList as Book

2. Instantiated it using a constructor that ensures all parameters/dependencies are met

3. Added a List and now every new Book is added to that list after construction

4. EXTRA: you dont need to create one scanner per line to scan. I created a single scanner for the whole BookLibrary instance. (Scanners are not thread-safe, so be careful with that)

5. TODO: Add a while loop and every time you add a Book increase the counter so you get a new id

   public class BookLibrary {
   private int counter = 1;
   private List bookList = new ArrayList<>();
   private Scanner generalScanner = new Scanner(System.in);

    public static void main(String[] args) {
   
        final BookLibrary bookLibrary = new BookLibrary();
   
        System.out.println("Do you want to 1:Add a book or 2:Remove a book");
        int choice = bookLibrary.generalScanner.nextInt();
        if (choice == 1) {
            System.out.println("You want to add a book");
            bookLibrary.addBook();
        }
    }
   
    public void addBook() {
        System.out.println("Enter the Name of the book");
        String name = this.generalScanner.nextLine();
        System.out.println("Enter the Author of the book");
        String author = this.generalScanner.nextLine();
        final Book book = new Book(name, author, this.counter);
        bookList.add(book);
    }
   

   Book class

   public class Book {
   String name;
   String author;
   int bookNum;

        public Book(String name, String author, int bookNum) {
            this.name = name;
            this.author = author;
            this.bookNum = bookNum;
        }
   
        public void printLibrary() {
            System.out.println("Book name: " + name);
            System.out.println("Author: " + author);
            System.out.println("Book Number: " + bookNum);
        }
    }