import java.util.HashMap;

import Utilities.Code;

public class Shelf $\{$

public static final int SHELF$\_$NUMBER$\_=0$;

public static final int SUBJECT$\_=1$;

private HashMap books $=$ new HashMap$()$;

private int shelfNumber;

private String subject;

@Deprecated

public Shelf$()\{$

$\}$

public Shelf$($int shelfNumber, String subject$)\{$

this.shelfNumber $=$ shelfNumber;

this.subject $=$ subject;

$\}$

public int getBookCount$($Book book$)\{$

$**$This returns the count of the book parameter stored on the shelf. If the book is not stored on the shelf it should return a $-1**$

public Code addBook$($Book book$)\{$

$**$Adds the parameter 'book' to the HashMap of books stored on the shelf

If the book already exists in the HashMap, the count should be incremented, and a SUCCESS code should be returned.

If the book does NOT exist on the shelf, and the subject matches, add the book to the shelf, set the count of the book to $1,$ and return a SUCCESS Code.

If the book does NOT exist on the shelf, and the subject DOES NOT match, return a SHELF$\_$SUBJECT$\_$MISMATCH$\_$ERROR Code.

If the book is successfully added, print a message that displays the toString for the Book, concatenated with $"$ added to shelf $"$ concatenated with the toString of the current Shelf.$**$

public Code removeBook$($Book book$)\{$

$**$If the parameter book is not present in the books hashMap, return a BOOK$\_$NOT$\_$IN$\_$INVENTORY$\_$ERROR Code and print a message like

Hitchhikers Guide To the Galaxy is not on shelf sci$-$fi

If the parameter book IS present in the books hashMap but has a count of $0,$ return a BOOK$\_$NOT$\_$IN$\_$INVENTORY$\_$ERROR Code and print a message like

No copies of Hitchhikers Guide To the Galaxy remain on shelf sci$-$fi

If the parameter book is in the books hashMap and the count is greater than $0$ decrement the count of books in the hashMap, return a SUCCESS Code and print a message like

Hitchhikers Guide To the Galaxy successfully removed from shelf sci$-$fi$**$

public String listBooks$()\{$

Returns a String listing all of the books on the shelf. The listing of books should match the following $($Each of the following is a separate shelf$)$:

$2$ books on shelf: $2$ : education

Headfirst Java by Grady Booch ISBN:$13372$

$1$ book on shelf: $3$ : Adventure

Count of Monte Cristo by Alexandre Dumas ISBN:$52971$

$3$ books on shelf: $1$ : sci$-$fi

Hitchhikers Guide To the Galaxy by Douglas Adams ISBN:$42-$w$-872$

Dune by Frank Herbert ISBN:$34-$w$-341$

$\}$

@Override

public String toString$()\{$

return shelfNumber $+"$ : $"+$ subject;

$\}$

public HashMap getBooks$()\{$

return books;

$\}$

public void setBooks$($HashMap books$)\{$

this.books $=$ books;

$\}$

public int getShelfNumber$()\{$

return shelfNumber;

$\}$

public void setShelfNumber$($int shelfNumber$)\{$

this.shelfNumber $=$ shelfNumber;

$\}$

public String getSubject$()\{$

return subject;

$\}$

public void setSubject$($String subject$)\{$

this.subject $=$ subject;

$\}$

@Override

public boolean equals$($Object o$)\{$

if $($this $==$ o$)$ return true;

if $($o $==$ null $||$ getClass$()!=$ o$.$getClass$())$ return false;

Shelf shelf $=($Shelf$)$ o;

if $($getShelfNumber$()!=$ shelf.getShelfNumber$())$ return false;

return getSubject$()!=$ null $?$ getSubject$().$equals$($shelf$.$getSubject$())$ : shelf.getSubject$()==$ null;

$\}$

@Override

public int hashCode$()\{$

int result $=$ getShelfNumber$()$;

result $=31*$ result $+($getSubject$()!=$ null $?$ getSubject$().$hashCode$()$ : $0)$;

return result;

$\}$

$\}$

Library Project: Shelf.java

V$2\mathrm{.}4\mathrm{.}2$

UML Diagram of Shelf.java