图书馆程序--图书的分配和借阅

Question

我应该用java创建一个库程序，允许您创建赞助者，最多可以查看3本书。我真的是java的初学者，所以我很抱歉，我的代码到处都是，可能没有意义。

下面是我尝试的图书馆类(我还有一个单独的赞助人、图书和图书接口类)我的主要关注点是：

• 我有两个ArrayLists，一个用于输入用户列表，另一个用于输入图书列表。然而，我如何才能将某些已结账的书籍分配给某个用户&确保它们的借入不超过3本？
• 我在主方法中输入了大量的代码，但是最后在静态和非静态的东西上出现了很多问题。
• 我如何才能为每一本书创建状态？例如，如果“远大的期望”被检查出来，如何将“借来的”分配给它，并确保没有其他人可以借到它？

这个程序进行到目前为止，但缺乏深度，因为我不知道如何在某一特定赞助人的情况下查阅书籍。

再次为我的代码中的不一致之处感到抱歉，我真的很感谢您的帮助！

​

import java.awt.List;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner; 
import java.util.Collections; 
public class Library 
{


	static ArrayList <Patron> UserList = new ArrayList<Patron>();
	static ArrayList <String> BookList = new ArrayList <String> (); 
	
	public static String status;
	public static String borrower; 
	public static String borrowDate; 
	public static String returnDate; 
	public String status1 = "Available";
	public String status2 = "Borrowed";
	
	
	public static void main(String[] args)
	{
		Scanner input = new Scanner(System.in);
		int choice = 0;
		System.out.println("********************Welcome to the Public Library!********************");
		System.out.println("              Please Select From The Following Options:               ");
		System.out.println("**********************************************************************");
		
		while(choice != 9)
		{
			System.out.println("1: Add new patron");
			System.out.println("2: Add new book");
			System.out.println("3: Edit patron");
			System.out.println("4: Edit book");
			System.out.println("5: Display all patrons");
			System.out.println("6: Display all books");
			System.out.println("7: Check out book");
			System.out.println("8: Check in book");
			System.out.println("9: Search book");
			System.out.println("10: Search Patron");
			System.out.println("9: Exit");
			choice = input.nextInt();

			
		switch(choice)
		{
		case 1: //Add new patron
			System.out.print("Enter patron first name: ");
			String firstName = input.next(); //read name from input
			System.out.print("Enter patron last name: ");
			String lastName = input.next(); 

			UserList.add(new Patron(firstName, lastName)); //add name to list
			System.out.println("-----You have successfully added a new patron!-----");
			break; 
							
		case 2: //Add new book
			System.out.print("Enter book title: ");
			String title1 = input.next();
				
			Scanner input1 = new Scanner(System.in);
			System.out.print("Enter book author: ");
			String author1 = input.next(); 

			Book book1 = new Book(title1);				
			BookList.add(title1);
			FullBookList.add(fullBook);
			System.out.println("-----You have successfully added a new book!-----");
			
			status = "available";
			borrowDate = "none";
			returnDate = "none";
			borrower = "none";
			
			break; 
			
		case 3: //Edit patron name
			System.out.println("Enter original patron name: ");
			String originalName = input.next(); 
			System.out.println("Enter edited patron name: ");
			String editedName = input.next(); 
			//Collections.replaceAll(UserList, originalName, editedName);
			if(UserList.contains(originalName))
			{
				
			}
				
		case 4: //edit book
			
			
		case 5: //display all patrons	
				System.out.println(UserList); 
				break; 
				
		case 6: //display all books 
				System.out.println(BookList); 
				break; 
				
		case 7: //check out a book
				Patron.CheckOutBook(); 
				break; 
		case 8: //check in a book
				Patron.CheckInBook(); 
				break; 
				
			
			}
		}
	}
}

​

​

import java.util.ArrayList;
import java.util.Scanner;

public class Patron 
{
	Scanner input = new Scanner(System.in);
	private String first; 
	private String last; 
	int bookCount = 0;	//amount books user has in pocket
	int books = 0;
	
	
	//constructor to "add new patron" by entering their name. 
	public Patron(String f, String l)
	{
		first = f; 
		last = l; 
	}
	
	public String toString()
	{
		return first + " " + last; 
	}
	
	public String getName() 
	{
		return first +  " " + last; 
	}

	public static void CheckOutBook()
	{
		System.out.println("Enter book title to be check out: ");
		Scanner input = new Scanner(System.in);
		String bookCheckOut = input.next(); 
		if(Library.BookList.contains(bookCheckOut))
		{
			Library.BookList.remove(bookCheckOut);
			System.out.println("-----" + bookCheckOut + " has been checked out!-----");
			System.out.println ("-------" + bookCheckOut + " is due in 7 days!-------");
							
		}
		else 
			System.out.println(bookCheckOut + " is not in the library. Please enter "
			+ "a different book to be checked out");
		
	}
	
	public static void CheckInBook()
	{
		System.out.println("Enter book title to be checked in: ");
		Scanner input = new Scanner(System.in);
		String bookCheckIn = input.next(); 
		if(Library.BookList.contains(bookCheckIn))
		{
			Library.BookList.add(bookCheckIn);
			System.out.println("-----" + bookCheckIn + " has been checked in!-----");	
							
		}
		else 
			System.out.println(bookCheckIn + " is not in the library. Please enter "
			+ "a different book to be checked out");
	}
	
	public boolean canBorrow()
	{
		if(bookCount <= 3)
		{
			return true; 
		} 
		else 
		{
			return false; 
		}
	}

}

​

Answer 1

注意:这可能需要对主循环进行一些重构.。

好的，在我看来，我们这里有三门课:一些赞助者，可以结账，还有一些书，有“可用”和“退房”的状态，还有一个图书馆，里面有书。所以，我们需要3门课：

我将从Book开始，并使用伪代码来解释要实现的概念。

class Book
{
    //private fields
    private final String title;
    private final String author;
    private Status available = true;
    //note--i would prefer using an Enum called status for this, 
    //but a boolean true/false value works adequately

    //Constructor
    public Book(string title, string author) {}

    //accessors for title, author, available
    //setter for available--used for Library only--there are better ways to ensure
    //Patrons can't set the status of the book, but for now this is the simplest way
}

正如您所看到的，Books有不需要更改的不可变字段，还有一个跟踪它状态的字段。更好的实现可能会使库跟踪图书状态，因为这样做更有逻辑意义和更好的代码，但这是一个简单的实现。

接下来是图书馆，它需要大量的书籍：

class Library
{
    private final ArrayList<Book> books;

    //Constructor
    public Library ()
    {
        books = loadBooks();
    }

    //some methods
    private ArrayList<Book> loadBooks () {}
    //however you want to create all your books (file input, whatever)

    public bool isBookAvailable (Book b)
    {
        if b isn't in library: return false
        else return (b in books).isAvailable()
    }

    public Book checkoutBook (Book b)
    { get book (checking availability, possibly returning a null Book), set status to unavailable, return it }

    public Book checkinBook (Book b)
    { check that this the book belongs to library, set status to available }
}

就像我之前说的，这并不完美。我可以花相当长的时间来讨论如何改进设计，但为了简单起见，不会。

现在，顾客们。一个问题是，顾客是否应该只有一家图书馆可以参观？或者他们会访问多个图书馆？我假设他们不止一次访问，因为有时图书馆没有你想要的所有书。

class Patron
{
    private final String name;
    private final Book[] books = new Book[3];//you can see I'm limiting them to 3 books
    private int index = 0;

    //Constructor
    public Patron (String name) {}

    //methods
    public void checkoutBook (Book b, Library l)
    {//could be tricky
        check books status in l (l.isBookAvailable(b))
        if available: 
            if space (index < 2) Book newBook = l.checkoutBook(b); books[index++] = newBook;
            else: no space
        else: not available
    }

    public void checkinBook (int bookIndex, Library l)
    {
         if bookIndex < 3:
             if books[index] != null:
                 l.checkinBook (books[index]);
                 books[index--] = null;
             else: no book
         else: not valid index
    }
}

当然，其他实用工具，如显示书籍(库、赞助人)和toString方法可能是有用的。但是现在主要的方法是创建一些赞助者，一个图书馆，并给顾客一个通过菜单登记和登记书籍的机会。您已经完成了繁重的工作；您现在可以对输入和输出进行工作。

有什么问题吗？