Question

Hello I'm working on a java program, called library which takes two previous classes I've made "Book" and Author. Library creates a place where books can be stored and checked in and out. Im having trouble in my Library class with the method getStatus not working after I check a book in or out. I will copy and paste a portion of my library code on here, I have a link for the code for the book author as well as the testing code if needed.

public class Library {
   /** Unique books in the library. */
   private Book[] books;
   /** Number of copies for each book. */
   private int[] copies;
   /** Number of copies currently checked out for each book. */
   private int[] checkedOut;
   /** Number of unique books in the library. */
   private int numBooks;
   /** Construct a new empty Library. */
   public Library(int librarySize) {
       books = new Book[librarySize];
       copies = new int[librarySize];
       checkedOut = new int[librarySize];
       numBooks = 0;
   }
   /**
   * Get the number of total copies of all books that exist in the library.
   *
   * @return Total number of copies in the library.
   */
   public int getTotalCopies() {
       int Totalcop = 0;
       for (int i = 0; i < numBooks; i++) {   //loops over number unique books that have copies
           Totalcop +=copies[i];                   //adds up the amount of copies for all books in one var
       }
       return Totalcop;
   }
   /**
   * Get the number of copies currently checked out.
   *
   * @return Total number of copies checked out.
   */
   public int getNumCheckedOut() {
       int Totalnum = 0;
       for (int i = 0; i < numBooks; i++) {   //loops over number of unqiue books checked out
           Totalnum += checkedOut[i];                   // adds up the amount of checked out books for all in one var
       }
       return Totalnum;
   }
   /**
   * Get a String representing the status of the library.
   *
   * @return Status string.
   */
   public String getStatus() {
       if (numBooks != 0) {                //if library is not empty
           //System.out.println(numBooks + " " + getTotalCopies() +" "+ " " +getNumCheckedOut());
           return "Total unique books: " + numBooks + "\n" + "Total number of copies: " + getTotalCopies() + "\n"
                   + "Total checked out: " + getNumCheckedOut();
       }
       return "Total unique books: 0\n" + "Total number of copies: 0\n" + "Total checked out: 0";
   }
   /**
   * Add all the books in the array to the library. Adds one copy of each book.
   *
   * @param newBooks Books to add.
   */
   public void addBooks(Book[] newBooks) {
       int currentSize = numBooks;                           //current size for
       int newSize = currentSize + newBooks.length;       //creats int for number of books after newBooks is added
                   //int of unique books from newBook not already in library
       int[] tempCopies = new int[newSize]; // sets temp array for copies
       int[] tempCheckedOut = new int[newSize]; // sets temp array for checkout
       Book[] tempBooks = new Book[newSize]; // sets temp array for books
       for (int i = 0; i < numBooks; i++) { // loops number of unique books in library
           tempBooks[i] = books[i]; // copies element from book to tempbook
           tempCopies[i] = copies[i]; // copies element from copies to tempcopies
           tempCheckedOut[i] = checkedOut[i]; // copies element from checkedout to tempcheckout
       }
       copies = tempCopies; // copies tempcopie into copies (with newsize)
       checkedOut = tempCheckedOut; // copies tempcheckedout into checkedout with new size
       books = tempBooks; // copies temp book into books with new size
      
       for (int j = 0; j < newBooks.length; j++) {   // loops for numb of newbooks
           boolean flag=true;                       //creates boolean for if newbook is copy   
           for (int i = 0; i < numBooks; i++) {   //loops for numb of unique books in library
               if(books[i].equals(newBooks[j]))           //if newbook is in library
               {
                   copies[i] += 1;                   // add a copy of that book               
                   flag=false;                       //changes boolean to false
                                           //if book is in library break out of if statement
               }
           }
           if(flag)   {                           //if boolean is true          
              
                                       //number of newBooks not already in library
           books[ numBooks] = newBooks[j]; // adds element from newBooks at the end of books
           copies[numBooks] += 1; //adds 1 copy for each unique book
           checkedOut[numBooks] = 0;
           numBooks ++;
           }
       }
      
   }
   /**
   * Add a single book the library.
   *
   * If the book is already present, adds another copy. If the book is new, add it
   * after the existing books.
   *
   * @param b Book to add.
   */
   public void addBook(Book b) {
       addBooks(new Book[] { b });       //calls addBook with just one book, therefore newSize is just one plus currentSize
   }
   /**
   * Checks out a book from the library if possible.
   *
   * @param b Book to check out.
   * @return String denoting success or failure.
   */
   public String checkOut ( Book b ) {
       for(int i =0; i < books.length; i++) { //loops over length of library "books"
           if(b.equals(books[i])) {           //checks to see if book b is already in library
               if(copies[i] != 0) {           //if it is make sure there are still copies left to be checked out
                   checkedOut[i]++;           //check out the book by adding one to checkOut at index i
                   copies[i] -= 1;               //one less copy of book since checked out.
                   return "Checked out!";
              
               }
              
               return "All out of copies.";
          
           }
       }
       return "Book not found.";
   }

   /**
   * Checks in a book to the library if possible.
   *
   * @param b Book to check in.
   * @return String denoting success or failure.
   */
   public String checkIn ( Book b ) {
       for(int i = 0; i < books.length; i++) { //loops over length of library "books"
           if(b.equals(books[i])) {           // checks to see if book b is already in library
               if(checkedOut[i] != 0) {       //makes sure that book was checked out
                   checkedOut[i] -= 1;           //checks the book in by subtracting of checkOut copies of book
                   return "Checked in!";
              
               }else {
                   return "All of our copies are already checked in.";
               }
           }      
       }
       return "Book not found.";
   }

   /**
   * Get string representation of entire library collection and status.
   *
   * @return String representation of library.
   */
   public String toString() {
       String a = "";
       int i = 0;
       while (i < books.length) {
           a = i + ". " + books[i].getTitle() + ". " + books[i].getAuthor() + ". " + " : " + copies[i] + "\n";
           i++;
           return a;
       }
       return getStatus();
   }

Answer 1

class Library {

        /** Unique books in the library. */
        private Book[] books;

        /** Number of copies for each book. */
        private int[] copies;

        /** Number of copies currently checked out for each book. */
        private int[] checkedOut;

        /** Number of unique books in the library. */
        private int numBooks;

        /** Construct a new empty Library. */
        public Library(int librarySize) {
                books = new Book[librarySize];
                copies = new int[librarySize];
                checkedOut = new int[librarySize];
                numBooks = 0;
        }

        /**
         * Get the number of total copies of all books that exist in the library.
         * 
         * @return Total number of copies in the library.
         */
        public int getTotalCopies() {
                int Totalcop = 0;
                for (int i = 0; i < numBooks; i++) {
                        Totalcop = +copies[i];
                }
                return Totalcop;
        }

        /**
         * Get the number of copies currently checked out.
         * 
         * @return Total number of copies checked out.
         */
        public int getNumCheckedOut() {
                int Totalnum = 0;
                for (int i = 0; i < numBooks; i++) {
                        Totalnum = +checkedOut[i];
                }
                return Totalnum;
        }

        /**
         * Get a String representing the status of the library.
         * 
         * @return Status string.
         */
        public String getStatus() {
                if (numBooks != 0) {
                        return "Total unique books: " + numBooks + "\n" 
                                        + "Total number of copies: " + getTotalCopies() + "\n"
                                        + "Total checked out: " + getNumCheckedOut();
                }
                return "Total unique books: 0\n" + "Total number of copies: 0\n" + "Total checked out: 0";

        }

        /**
         * Add all the books in the array to the library. Adds one copy of each book.
         * 
         * @param newBooks Books to add.
         */
        public void addBooks(Book[] newBooks) {
                int currentSize = numBooks;
                int newSize = currentSize + newBooks.length;

                if (newSize > books.length) {
                        // we need to resize.
                        int[] tempCopies = new int[newSize];
                        int[] tempCheckedouts = new int[newSize];
                        Book[] tempBooks = new Book[newSize];
                        for (int i = 0; i < numBooks; i++) { // loops for length of books
                                tempBooks[i] = books[i]; // copies element from books to tempbook
                                tempCopies[i] = copies[i];
                                tempCheckedouts[i] = checkedOut[i];
                        }

                        copies = tempCopies;
                        checkedOut = tempCheckedouts;
                        books = tempBooks;
                }

                for (int j = 0; j < newBooks.length; j++) { // loops for length of newBooks
                        books[j + numBooks] = newBooks[j]; // copies elemnt from newBooks to tempbook
                }
                numBooks += newBooks.length;
        }

        /**
         * Checks out a book from the library if possible.
         * 
         * @param b Book to check out.
         * @return String denoting success or failure.
         */
        public String checkOut(Book b) {
                for (int i = 0; i < books.length; i++) {
                        if (b.equals(books[i])) {
                                if (copies[i] == 0) { // problem with index of copies
                                        return "No copies available.";
                                }
                                if (copies[i] == checkedOut[i]) { // problem with index of copies
                                        return "All out of copies.";
                                }

                                checkedOut[i] += 1;
                                return "Checked out!";
                        }
                }
                return "Book not found.";
        }

        /**
         * Checks in a book to the library if possible.
         * 
         * @param b Book to check in.
         * @return String denoting success or failure.
         */
        public String checkIn(Book b) {
                for (int i = 0; i < books.length; i++) {
                        if (b.equals(books[i])) {
                                if (copies[i] == 0) { // problem with index of copies
                                        return "No copies available.";
                                }
                                if (0 == checkedOut[i]) { // problem with index of copies
                                        return "No copies checkedout.";
                                }

                                checkedOut[i] -= 1;
                                return "Check in!";
                        }
                }
                return "Book not found.";
        }

        /**
         * Add a single book the library.
         *
         * If the book is already present, adds another copy. If the book is new, add it
         * after the existing books.
         * 
         * @param b Book to add.
         */
        public void addBook(Book b) {
                addBooks(new Book[] { b });
        }
}

please use above code.. If any issues, ask in comments..