Changing object name with input

The code should store each book in a List so that they may be accessed later in the code. The name is really of no importance other than it identifies your object within code. Even if you could change the name of the local variable book your issue would still remain.

The issue you experience is more related to scope and object instances. When you call new Book(..) you create a new instance of a book. This instance of book's scope is limited to the code block {} executed by the while loop. This means that outside the loop the instance of book is inaccessible.

In order to access the instance of book outside the loop, you could create a book outside the loop like so:

Book book;

while(...){
   book = new Book(...);
}

The issue with this method is that you are creating several instances of book, so the reference to the book will get overwritten with the newest book for each iteration of the loop.

This creates the necessity for something to hold multiple books. Instantly an array may come to mind, however the size of arrays is static and a user may enter 1..n books. This does not make an array a good choice for storing the books.

This is where the List and ArrayList come into play. A List is a data structure that holds multiple object instances. It can be expanded easily using the add(Object) method. A full description of a List and an ArrayList is beyond the scope of this answer, but I offer the following resource: http://docs.oracle.com/javase/tutorial/collections/

Final Solution

    List<Book> books = new ArrayList<Book>();
    while(!answer.equals("stop"))
        {
        //Enters book's information  and stores it in the object book1  
        System.out.println("Book-" + count);    

        title = input.next();
        author = input.next();
        ISBN = input.next();
        copies = input.nextInt();

        Book book1 = new Book(title,author, ISBN, copies);
        books.add(book1);

        printLn("");
        printLn("Do you wish stop adding books? N || stop");      
        answer = input.next();
     }

     //Iterating the book list outside the loop
     for(Book book:books){
       //this call may vary depending on the book implementation
       System.out.println(book.getTitle());
     }