ref: b0e7cab307f99283490c5fd1d3e7d085492c4155
dir: /Main.java/
//package BookProj; // XXX get rid of *s // handle throws // make whatever you can final /* import java.util.regex.Pattern; // Pattern, Matcher import java.util.Matcher; // Scanner, ArrayList import java.util.Scanner; */ import java.util.*; import java.time.LocalDateTime; import java.util.regex.Pattern; import java.util.regex.Matcher; import java.io.Console; import java.io.File; enum Err { Ok, NoBook, /* no such book has found */ BookReserved, /* book is reserved by someone else */ NoBookReserved, /* no book is revserved */ NoUser, /* no such user has found */ UserHasABook, /* User has already registered a book */ UserHasNoBook, Age; /* age doesn't match */ } enum Role { Admin, User; } enum BookAttr { ISBN, Status, Name, Author, AgeGroup, Abstract, Owner; } enum AdminAttr { Username, role, Reserved, ID, RegTime, // Password, Active; } enum UserAttr { Username, role, Reserved, ID, RegTime, Age, Active; } interface Library { /* admin */ boolean Login(Admin a, String pass); void Logout(Admin a); Admin NewAdmin(String user, String pass); void DelAdmin(Admin a); boolean CheckAdmin(String a); Admin MatchAdmin(String un); boolean FindAdmin(AdminAttr k, Pattern p); /* user */ boolean Login(User u); // void Logout(User u); // User NewUser(); // void DelUser(User u); boolean CheckUser(String u); User MatchUser(String un); boolean FindUser(UserAttr k, Pattern p); /* books */ Err TakeBook(String un, String isbn); Err TakeBook(Admin u, Book b); Err TakeBook(User u, Book b); Err ReturnBook(User u); Err ReturnBook(Admin u); Book NewBook(String isbn, String name, String author, int agegroup, String abst); void DelBook(Book b); boolean CheckBook(String ISBN); Book MatchBook(String isbn); boolean FindBook(BookAttr k, Pattern p); /* Err ReturnBook(Book b); boolean WriteStatus(); boolean FindBook(boolean q); for Status value searchs */ interface UI { void Program(); void LoginMenu(); /* checks password with user, gets input from GetPassword */ // boolean AskPass(Admin u); // boolean AskPass(User u); /* different Menus, for different Users to handle */ void Menu(Admin u); // void Menu(User u); /* Gets a String, either console or scanner, checks if it's valid or not, and encrypt it */ String GetUsername(); String GetPassword(); /* asks for user/book info, returns username/isbn if it exists */ // String AskAdmin(); // String AskUser(); // String AskBook(); /* search foolan menu */ // void SearchAdmin(); void SearchUser(); void SearchBook(); /* add foolan menu */ void AddAdmin(); // void AddUser(); void AddBook(); /* remove foolan menu */ // void RemAdmin(); // void RemUser(); // void RemBook(); // maybe it's stolen /* list foolan menu */ void ListAdmin(); void ListUser(); void ListBook(); /* take and return book menus */ void TakeMenu(Admin a); void TakeMenu(User u); // void ReturnMenu(Admin a); // void ReturnMenu(User u); /* handles result of Take/Return menu */ void Result(Err res); } } /* i personally don't use it but here is a converter */ class Books { HashMap<BookAttr, String> Book = new HashMap<BookAttr, String>(); HashMap<String, HashMap> Booklist = new HashMap<String, HashMap>(); HashMap<String, TreeMap> Mkbl(HashMap<String, Book> bl) { HashMap<String, TreeMap> list = new HashMap<String, TreeMap>(); for(Book i: bl.values()) { list.put(i.getISBN(), i.toMap()); } return list; } } class Book { /* book is untaken by default */ private boolean Status = false; private String Abstract, Author, Name, ISBN; private String Owner = ""; /* Username of user who reserved it */ private int AgeGroup; /* should a register be a constractor? XXX should it even named register? */ Book(String isbn, String name, String author, int age, String abs) { /* joy of joys willy */ this.ISBN = isbn; this.Name = name; this.Author = author; this.AgeGroup = age; this.Abstract = abs; } boolean AgeOk(int age) { if(this.AgeGroup <= age) return true; else return false; } boolean setOwner(String u) { if(!this.Owner.isEmpty()) { System.err.println("A User (ID:" + this.getOwner() + ") already got the book"); return false; } this.Owner = u; return true; } boolean setStatus(boolean b) { if(this.Status == b) { System.err.println("book (ISBN: " + this.getISBN() + ") status already set to: " + this.Status); return false; } this.Status = b; return true; } boolean getStatus() { return Status; } String getAbstract() { return this.Abstract; } String getAuthor() { return this.Author; } String getName() { return this.Name; } String getISBN() { return this.ISBN; } int getAgeGroup() { return this.AgeGroup; } String getOwner() { return this.Owner; } TreeMap<BookAttr, String> toMap() { TreeMap<BookAttr, String> temp = new TreeMap<BookAttr, String>(); temp.put(BookAttr.ISBN, this.ISBN); temp.put(BookAttr.Status, Boolean.toString(this.Status)); temp.put(BookAttr.Name, this.Name); temp.put(BookAttr.Author, this.Author); temp.put(BookAttr.AgeGroup, Integer.toString(this.AgeGroup)); temp.put(BookAttr.Abstract, this.Abstract); temp.put(BookAttr.Owner, this.Owner); return temp; } } abstract class BasicUser { private Role role; private String Username, Reserved; private int ID; private LocalDateTime RegTime; public boolean Active = false; // abstract boolean IsReserved(String ISBN); BasicUser(Role r, String u, int id, LocalDateTime rt) { this.role = r; this.Username = u; this.ID = id; this.RegTime = rt; } Role getRole() { return this.role; } String getUsername() { return this.Username; } int getID() { return this.ID; } boolean setReserved(String ISBN) { /* ensure he has no books */ if(this.Reserved == null) { /* ensure book is not taken by someone else if( return true; */ return true; } else { System.err.println("the user already have a book"); return false; } } boolean hasReserved() { if(this.Reserved.isEmpty()) return false; else return true; } String getReserved() { return this.Reserved; } LocalDateTime getRegTime() { return this.RegTime; } } class Admin extends BasicUser { private String Password; Admin(String user) { super(Role.Admin, user, (int)(Math.random()*100), LocalDateTime.now()); } Admin(String user, String Pass) { /* maybe check if password is too easy? */ super(Role.Admin, user, (int)(Math.random()*100), LocalDateTime.now()); this.setPassword(Pass); } boolean setReserved(String ISBN) { return false; /* XXX */ } boolean isReserved(String ISBN) { return false; /* XXX */ } boolean checkPass(String pass) { if(this.Password.equals(pass)) return true; else return false; } void setPassword(String pass) { this.Password = pass; } TreeMap<AdminAttr, String> toMap() { TreeMap<AdminAttr, String> temp = new TreeMap<AdminAttr, String>(); temp.put(AdminAttr.Username, getUsername()); temp.put(AdminAttr.role, getRole().toString()); temp.put(AdminAttr.Reserved, getReserved()); temp.put(AdminAttr.ID, Integer.toString(getID())); temp.put(AdminAttr.RegTime, getRegTime().toString()); /* temp.put(AdminAttr.Password, this.Password); secrect secrect secrect */ temp.put(AdminAttr.Active, Boolean.toString(this.Active)); return temp; } } class User extends BasicUser { private int Age; User(String username, int age) { super(Role.User, username, (int)(Math.random()*1000+101), LocalDateTime.now()); this.Age = age; } int getAge() { return this.Age; } boolean IsReserved(Book b) { if(this.getReserved().equals(b.getISBN())) return true; else return false; } boolean IsReserved(String ISBN) { if(this.getReserved() == ISBN) return true; else return false; } TreeMap<UserAttr, String> toMap() { TreeMap<UserAttr, String> temp = new TreeMap<UserAttr, String>(); temp.put(UserAttr.Username, this.getUsername()); temp.put(UserAttr.role, getRole().toString()); temp.put(UserAttr.Reserved, getReserved()); temp.put(UserAttr.ID, Integer.toString(getID())); temp.put(UserAttr.RegTime, getRegTime().toString()); temp.put(UserAttr.Age, Integer.toString(this.Age)); temp.put(UserAttr.Active, Boolean.toString(this.Active)); return temp; } } class Lib implements Library { /* Username, Admin/User, ISBN, Book */ private HashMap<String, Admin> AdminList = new HashMap<String, Admin>(); private HashMap<String, User> UserList = new HashMap<String, User>(); private HashMap<String, Book> BookList = new HashMap<String, Book>(); private ArrayList<Admin> AdminQuery = new ArrayList<Admin>(); private ArrayList<User> UserQuery = new ArrayList<User>(); private ArrayList<Book> BookQuery = new ArrayList<Book>(); static Admin adm; static User usr; int ResCount = 0; /* is hasNextLine is of any of use? i wonder, says timmy */ public int readint(Scanner s, String errmsg, String inputmsg) { System.out.println(inputmsg); while(!s.hasNextLine()) { System.err.println(errmsg); System.out.print(inputmsg); s.nextLine(); } return s.nextInt(); } public String readstr(Scanner s, String errmsg, String inputmsg) { System.out.println(inputmsg); while(!s.hasNextLine()) { System.err.println(errmsg); System.out.print(inputmsg); s.nextLine(); } return s.nextLine(); } public boolean Login(Admin u, String pass) { /* clear null */ adm = null; if(u.Active) throw new IllegalStateException("Admin is already active?"); /* maybe later i want to do more stuff here */ if(u.checkPass(pass)) { u.Active = true; adm = u; return true; } else return false; } public void Logout(Admin u) { boolean b = false; for(Admin i : this.AdminList.values()) { if(i == u) b = true; } if(!b) throw new NoSuchElementException("No such Admin exists."); u.Active = false; } public boolean Login(User u) { if(u.Active) throw new IllegalStateException("Admin is already active?"); /* maybe later i want to do more stuff here */ u.Active = true; return true; } public Admin NewAdmin(String user, String pass) { Admin a; for(Admin i : this.AdminList.values()) { if(i.getUsername().equals(user)) throw new IllegalArgumentException("Admin already exists"); } /* if user is "admin", use defaults */ if(user.equals("admin")) a = new Admin("admin", "pass"); else a = new Admin(user, pass); if(this.AdminList.size() == 0) adm = a; this.AdminList.put(a.getUsername(), a); return a; } /* i could've made them overload, however, this might led to unwanted results */ public void DelAdmin(Admin u) { if(!u.getReserved().isEmpty()) { System.err.println("Admin " + u.getUsername() + " has a reserved book."); return; } this.AdminList.remove(u.getUsername(), u); } public void DelUser(User u) { if(!u.getReserved().isEmpty()) { System.err.println("User " + u.getUsername() + " has a reserved book."); return; } this.UserList.remove(u.getUsername(), u); } public Book NewBook(String isbn, String name, String author, int agegroup, String abst) { for(Book b : this.BookList.values()) { if(b.getISBN().equals(isbn)) throw new IllegalStateException("Book already exist"); } Book b = new Book(isbn, name, author, agegroup, abst); this.BookList.put(isbn, b); return b; } public void DelBook(Book b) { if(!b.getOwner().isEmpty()) { // System.err.println("User " + b.getOwner() + " have reserved this book."); throw new IllegalStateException("Book is reserved."); } this.BookList.remove(b.getISBN()); } public boolean CheckBook(String isbn) { boolean b = false; for(Book i : this.BookList.values()) { if(i.getISBN().equals(isbn)) b = true; } if(!b) { System.err.println("No such user found, try again"); } return b; } public Book MatchBook(String isbn) { Book b = null; for(Book i : this.BookList.values()) { if(i.getISBN().equals(isbn)) b = i; } if(b == null) throw new NoSuchElementException("No such Admin exists."); return b; } /* public boolean FindBook(BookAttr k, Pattern p) { // this.BookQuery.clear(); Matcher m; switch(k) { // XXX should i use i.getFoolan.contains()? case AgeGroup: for(Book i : BookList.values()) { m = p.matcher(Integer.toString(i.getAgeGroup())); if(m.find()) this.BookQuery.add(i); } break; case Abstract: for(Book i : BookList.values()) { m = p.matcher(i.getAbstract()); if(m.find()) this.BookQuery.add(i); } break; case Author: for(Book i : BookList.values()) { m = p.matcher(i.getAuthor()); if(m.find()) this.BookQuery.add(i); } break; case Name: for(Book i : BookList.values()) { m = p.matcher(i.getName()); if(m.find()) this.BookQuery.add(i); } break; case ISBN: for(Book i : BookList.values()) { m = p.matcher(i.getISBN()); if(m.find()) this.BookQuery.add(i); } break; default: // XXX write stuff and nag in case of invalid stuff break; } if(this.BookQuery.size() == 0) return false; else return true; } */ public boolean FindBook(BookAttr k, Pattern p) { Matcher m; this.BookQuery.clear(); for(Book i: this.BookList.values()) { m = p.matcher(i.toMap().get(k)); if(m.find()) BookQuery.add(i); } if(this.BookQuery.size() == 0) return false; else return true; } public boolean CheckAdmin(String a) { for(Admin i : this.AdminList.values()) { if(i.getUsername().equals(a)) { return true; } } return false; } public Admin MatchAdmin(String un) { Admin a = null; for(Admin i : this.AdminList.values()) { if(i.getUsername().equals(un)) a = i; } if(a == null) throw new NoSuchElementException("No such Admin exists."); return a; } public boolean FindAdmin(AdminAttr k, Pattern p) { Matcher m; this.AdminQuery.clear(); for(Admin i: this.AdminList.values()) { m = p.matcher(i.toMap().get(k)); if(m.find()) AdminQuery.add(i); } if(this.AdminQuery.size() == 0) return false; else return true; } public boolean CheckUser(String u) { for(User i : this.UserList.values()) { if(i.getUsername().equals(u)) { return true; } } return false; } public User MatchUser(String un) { User u = null; for(User i : this.UserList.values()) { if(i.getUsername().equals(un)) u = i; } if(u == null) { throw new NoSuchElementException("No such User exists."); } return u; } public boolean FindUser(UserAttr k, Pattern p) { Matcher m; this.UserQuery.clear(); for(User i: this.UserList.values()) { m = p.matcher(i.toMap().get(k)); if(m.find()) UserQuery.add(i); } if(this.UserQuery.size() == 0) return false; else return true; } public boolean FindBook(boolean q) { /* flush last query */ this.BookQuery.clear(); for(Book i : BookList.values()) { if(i.getStatus()) this.BookQuery.add(i); } if(this.BookQuery.size() == 0) return false; else return true; } /* user/admin's ID, ISBN */ public Err TakeBook(String un, String isbn) { Book b = this.BookList.get(isbn); if(this.CheckUser(un)) return TakeBook(MatchUser(un), b); else if(this.CheckAdmin(un)) return TakeBook(MatchAdmin(un), b); else return Err.NoUser; } /* they shouldn't be able to get a book, but still */ public Err TakeBook(Admin u, Book b) { /* check if book is taken */ if(b.getStatus()) return Err.BookReserved; /* he has some book? blasmphy! */ if(!u.getReserved().isEmpty()) return Err.UserHasABook; /* check if ages match admin has no age anyway if(!b.AgeOk(u.getAge())) return Err.Age; */ u.setReserved(b.getISBN()); b.setOwner(u.getUsername()); this.ResCount++; return Err.Ok; } public Err TakeBook(User u, Book b) { /* check if book is taken */ if(b.getStatus()) return Err.BookReserved; /* he has some book? blasmphy! */ if(!u.getReserved().isEmpty()) return Err.UserHasABook; /* check if ages match */ if(!b.AgeOk(u.getAge())) return Err.Age; u.setReserved(b.getISBN()); b.setOwner(u.getUsername()); this.ResCount++; return Err.Ok; } public Err ReturnBook(Admin u) { Book b; if(u.getReserved().isEmpty()) return Err.NoBookReserved; if(!CheckBook(u.getReserved())) return Err.NoBook; b = MatchBook(u.getReserved()); u.setReserved(null); b.setOwner(null); this.ResCount--; return Err.Ok; } public Err ReturnBook(User u) { Book b; if(u.getReserved().isEmpty()) return Err.NoBookReserved; if(!CheckBook(u.getReserved())) return Err.NoBook; b = MatchBook(u.getReserved()); u.setReserved(null); b.setOwner(null); this.ResCount--; return Err.Ok; } class conUI implements UI { public void Program() { while(true) { /* there is no admin! */ if(AdminList.size() == 0) { AddAdmin(); adm.Active = true; } else this.LoginMenu(); /* only exits if user either logs out or smh */ this.Menu(adm); /* user wants to quit */ if(adm.Active) return; } } public void LoginMenu() { String un, pass; System.out.print("Login> "); un = GetUsername(); if(CheckAdmin(un)) { pass = this.GetPassword(); Admin a = MatchAdmin(un); if(Login(a, pass)) { System.out.println("Auth as " + a.getUsername() + " sucessful"); return; } else { System.out.println("Auth fail"); this.LoginMenu(); } } else if(CheckUser(un)) { User u = MatchUser(un); if(Login(u)) { System.out.println("Login sucessful"); } } else { /* fool em! */ this.GetPassword(); System.out.println("Auth fail"); this.LoginMenu(); } } /* checks if password is valid, kinda like login */ public boolean AskPass(Admin u) { String pass; System.out.println("Enter " + u.getUsername() + "'s password:"); return u.checkPass(GetPassword()); } public void Menu(Admin a) { int in; Scanner s = new Scanner(System.in); System.out.println("Welcome, " + a.getUsername() + "!"); while(true) { System.out.print( "\n" + " 1) add admin\n" + " 2) add user\n" + " 3) add book\n\n" + " 4) search admin\n" + " 5) search user\n" + " 6) search book\n\n" + " 7) list admin\n" + " 8) list user\n" + " 9) list book\n\n" + "10) delete admin\n" + "11) delete user\n" + "12) delete book\n\n" + "13) take book\n" + "14) return book\n\n" + "15) logout\n" + "99) quit!\n"); System.out.print("menu> "); while(!s.hasNextInt()) { System.err.println("Please enter a valid input"); System.out.print("menu> "); s.nextLine(); } in = s.nextInt(); switch(in) { case 1: if(this.AskPass(adm)) this.AddAdmin(); else System.err.println("Incorrect Password."); break; /* case 2: if(this.AskPass(adm)) this.AddUser(); else System.err.println("Incorrect Password."); break; */ case 3: this.AddBook(); break; /* case 4: this.SearchAdmin(); break; case 5: this.SearchUser(); break; */ case 6: this.SearchBook(); break; case 7: this.ListAdmin(); break; case 8: this.ListUser(); break; case 9: this.ListBook(); break; case 10: // System.out.println("This action requires admin password"); // if(this.AskPass(adm)) /* current admin */ // this.RemAdmin(); // else // System.err.println("Incorrect Password."); break; case 11: System.out.println("This action requires admin password"); // if(this.AskPass(adm)) /* current admin */ // this.RemUser(); // else // System.err.println("Incorrect Password."); break; case 12: // this.RemBook(); break; case 13: this.TakeMenu(adm); break; case 14: // this.ReturnMenu(); break; case 15: System.out.println("Logging out..."); Logout(adm); return; /* quit */ case 99: System.out.print("Are you sure? (y/N)> "); s.nextLine(); if(s.nextLine().equals("y")) return; break; default: System.out.println("Invalid answer!, please try again."); break; } } } public String GetUsername() { Scanner s = new Scanner(System.in); String user; do { System.out.print("Username?> "); user = s.nextLine(); }while(user.contains(" ")); return user; } public String GetPassword() { String pass; if(System.console() != null) { Console c = System.console(); do { pass = new String(c.readPassword("Password?> ")); }while(pass.contains(" ")); } else { /* no console? */ Scanner s = new Scanner(System.in); do { System.out.print("Password?> "); pass = s.nextLine(); }while(pass.contains(" ")); } /* encrypt it! */ return Integer.toString(pass.hashCode()); } public void SearchUser() { String attr, patt; Pattern pattern; UserAttr ua; Scanner s = new Scanner(System.in); System.out.println("Attr: Username, Reserved, ID, RegTime, Age, Active"); System.out.print("Find> What?> "); attr = s.nextLine(); if(attr.equalsIgnoreCase("Username")) ua = UserAttr.Username; else if(attr.equalsIgnoreCase("Reserved")) ua = UserAttr.Reserved; else if(attr.equalsIgnoreCase("ID")) ua = UserAttr.ID; else if(attr.equalsIgnoreCase("RegTime")) ua = UserAttr.RegTime; else if(attr.equalsIgnoreCase("Age")) ua = UserAttr.Age; else if(attr.equalsIgnoreCase("Active")) ua = UserAttr.Active; else { System.err.println("Invalid Attr"); return; } System.out.println("Find> Pattern?> "); patt = s.nextLine(); pattern = Pattern.compile(patt, Pattern.CASE_INSENSITIVE); if(FindUser(ua, pattern)) { for(User i : UserList.values()) { for(UserAttr j : UserAttr.values()) System.out.print(j + " | "); System.out.println(); for(User j : UserQuery) { for(UserAttr a : i.toMap().keySet()) System.out.print(j.toMap().get(a) + " | "); System.out.println(); } } } else System.err.println("No match has found"); } public void SearchBook() { String attr, patt; Pattern pattern; BookAttr ba; Scanner s = new Scanner(System.in); System.out.println("Attr: Status, Name, Abstract, ISBN, AgeGroup etc."); System.out.print("Find> What?> "); attr = s.nextLine(); if(attr.equalsIgnoreCase("Status")) ba = BookAttr.Status; else if(attr.equalsIgnoreCase("Name")) ba = BookAttr.Name; else if(attr.equalsIgnoreCase("Author")) ba = BookAttr.Author; else if(attr.equalsIgnoreCase("Abstract")) ba = BookAttr.Abstract; else if(attr.equalsIgnoreCase("ISBN")) ba = BookAttr.ISBN; else if(attr.equalsIgnoreCase("AgeGroup")) ba = BookAttr.AgeGroup; else { System.err.println("Invalid Attr"); return; } System.out.println("Find> Pattern?> "); patt = s.nextLine(); pattern = Pattern.compile(patt, Pattern.CASE_INSENSITIVE); if(FindBook(ba, pattern)) { // XXX add isRegistered() for(Book i : BookList.values()) { for(BookAttr j : BookAttr.values()) System.out.print(j + " | "); System.out.println(); for(Book j : BookQuery) { for(BookAttr a : j.toMap().keySet()) System.out.print(j.toMap().get(a) + " | "); System.out.println(); } } } else System.err.println("No match has found"); } public void AddAdmin() { /* isn't java wonderful billy? */ String user, pass; System.out.println("Setting up Admin:"); do { System.out.print("Add admin> "); user = this.GetUsername(); if(user.equals("")) return; }while(CheckAdmin(user)); do { pass = this.GetPassword(); }while(pass.equals("")); NewAdmin(user, pass); } /* make checks better, reject empty input etc, regex perhaps? */ public void AddBook() { int agegroup; String name, isbn, author, abs; Scanner s = new Scanner(System.in); System.out.print("Book> Name?> "); name = s.nextLine(); if(name.equals("")) return; System.out.print("Book> ISBN?> "); isbn = s.nextLine(); if(isbn.equals("")) return; System.out.print("Book> Author?> "); author = s.nextLine(); if(author.equals("")) return; // XXX on a related note, should i care about dealing with multiline stuff? System.out.print("Book> Abstract?> "); abs = s.nextLine(); if(abs.equals("")) return; System.out.print("Book> Age Group?> "); while(!s.hasNextInt()) { System.out.println("Please enter a valid input"); System.out.print("Book> Age Group?> "); s.nextLine(); } agegroup = s.nextInt(); Book b = NewBook(isbn, name, author, agegroup, abs); } public void Rembook() { } public void ListAdmin() { for(AdminAttr i : AdminAttr.values()) System.out.print(i + " | "); System.out.println(); for(Admin i : AdminList.values()) { for(AdminAttr a : i.toMap().keySet()) System.out.print(i.toMap().get(a) + " | "); System.out.println(); } } public void ListUser() { for(UserAttr i : UserAttr.values()) System.out.print(i + " | "); System.out.println(); for(User i : UserList.values()) { for(UserAttr a : i.toMap().keySet()) System.out.print(i.toMap().get(a) + " | "); System.out.println(); } } public void ListBook() { for(BookAttr i : BookAttr.values()) System.out.print(i + " | "); System.out.println(); for(Book i : BookList.values()) { for(BookAttr a : i.toMap().keySet()) System.out.print(i.toMap().get(a) + " | "); System.out.println(); } } public void TakeMenu(Admin u) { String isbn; Scanner s = new Scanner(System.in); if(!u.getReserved().isEmpty()) { System.err.println("Current Admin has already has a book (ISBN: " + u.getReserved() + ")."); return; } System.out.println("Which book do you want to take? (you may find it's ISBN by Search menu)"); do { System.out.println("Take> ISBN?> "); isbn = s.nextLine(); if(isbn.equals("")) return; if(!CheckBook(isbn)) System.err.println("No such book found, please try again"); }while(isbn.contains(" ") || !CheckBook(isbn)); Result(TakeBook(u, MatchBook(isbn))); } public void TakeMenu(User u) { String isbn; Scanner s = new Scanner(System.in); if(!u.getReserved().isEmpty()) { System.err.println("Current User has already has a book (ISBN: " + u.getReserved() + ")."); return; } System.out.println("Which book do you want to take? (you may find it's ISBN by Search menu)"); do { System.out.println("Take> ISBN?> "); isbn = s.nextLine(); if(isbn.equals("")) return; if(!CheckBook(isbn)) System.err.println("No such book found, please try again"); }while(isbn.contains(" ") || !CheckBook(isbn)); Result(TakeBook(u, MatchBook(isbn))); } public void Result(Err res) { switch(res) { case NoBook: System.err.println("No such book has found"); break; case BookReserved: System.err.println("This book is reserved by someone else"); break; case NoBookReserved: System.err.println("No book is reserved"); break; case NoUser: System.err.println("No such User has found"); break; case UserHasABook: System.err.println("User has already registered a book"); break; case UserHasNoBook: System.err.println("User has no book"); break; case Age: System.err.println("Age doesn't match!"); break; case Ok: default: System.out.println("Done!"); break; } } } /* end of conUI */ } public class Main { public static void main(String args[]) { Lib l = new Lib(); Lib.UI ui = l.new conUI(); ui.Program(); } }