字符串和另一个数组列表的 ArrayList

Question

so i'm making a program to manage a book store, heres an example of whats supposed to do with the the following main:

        bookStore bookStore = new bookStore("Lelo");
        book l1 = new TecnicalBook("H. Schildt", "\"Java: The Complete Reference\"", 80, "Computer Science- Java");
        bookStore.addBook(l1);
        book l2= new AdventureBook("A. Christie", "\"The Man in the Brown Suit\"", 75, 14);
        bookStore.addBook(l2);
                
        
        Client c1 = new Premium("B. Antunes", "antunes@books.com");
        bookStore.addClient(c1);
        Client c2 = new Frequent("A. Oliveira", "oliveira@books.com");
        bookStore.addClient(c2);
        System.out.println("Initial stock:");
        bookStore.showBooks();
        bookStore.sale(l1, c1);
        System.out.println("Stock after selling:");
        bookStore.showBooks();
        System.out.println("Sales Volume:"+bookStore.SalesVolume);        
        bookStore.showClientsBooks(c1);

Should show this result:

Initial stock:
Author:H. Schildt   Title:"Java: The Complete Reference"   Base Price:80.0
Author:A. Christie   Title:"The Man in the Brown Suit"   Base Price:75.0
B. Antunes bought "Java: The Complete Reference", Tecnical Book of Computer Science- Java, for 72.0
Stock after selling:
Author:A. Christie   Title:"The Man in the Brown Suit"   Base Price:75.0
Sales Volume:72.0
B. Antunes bought: "UML Distilled". "The Man in the Brown Suit".

The only part that i cant do is the last line, showing the products that each client has bought, i was thinking of making an class that contained a string with the clients name and an arraylist of a book class, and then having an array list of that class for each client, but i'm not sure how to make this and theres probably a better way, Thanks

edit: i have this classes: class book class tecnicalbook extends book class adventurebook extends book

class client class regular extends client class frequent extends client class premium extends client

and i have the bookstore class where i have an array list of book and client objects.

Answer 1

You can add a list of Books to your Client class to keep track of sales:

class Client {

    ...

    private List<Book> books;

    ClientBooks(Client client) {
        ...

        this.books = new ArrayList<>();
    }

    public void addBook(Book book) {
        this.books.add(book);
    }

    public void printBooks() {
        for (Book book : this.books) {
            System.out.println(book);
        }
    }
}

Selling a book can be implemented like this:

List<Client> clients = ...

String buyer = ...
Book book = ...

for(Client client : clients) {
    if (client.getName().equals(buyer)) {
        client.addBook(book);
    }
}

Answer 2

It is important to override toString in each class. Then when your print the instance of that class, the string will print instead of some strange value.

This method also allows you to add all the books at once or individual books if you choose.

This class has not been tested but it should give you an idea of how to procede.

class Client {
  String name;
  private List<Book> clientBooks = new ArrayList<>();
  public Client(String name) {
     this.name = name;
  }

  public addBooks(List<Book> books) {
      clientBooks.addAll(books);
  }

  public void addBook(Book bk) {
      clientBooks.add(bk);
  }

  public String toString() {
     StringBuilder sb = new StringBuilder(name).append(":");
     // add either the entire toString for book here or just selected
     // items like the title.  It's up to you.
     for (Book b :clientBooks) {
        sb.append(b.toString()).append(", ");
     }
     
     return sb.toString().substring(0,sb.length()-2);
  }
}

Answer 3

so i'm making a program to manage a book store, heres an example of whats supposed to do with the the following main:

        bookStore bookStore = new bookStore("Lelo");
        book l1 = new TecnicalBook("H. Schildt", "\"Java: The Complete Reference\"", 80, "Computer Science- Java");
        bookStore.addBook(l1);
        book l2= new AdventureBook("A. Christie", "\"The Man in the Brown Suit\"", 75, 14);
        bookStore.addBook(l2);
                
        
        Client c1 = new Premium("B. Antunes", "antunes@books.com");
        bookStore.addClient(c1);
        Client c2 = new Frequent("A. Oliveira", "oliveira@books.com");
        bookStore.addClient(c2);
        System.out.println("Initial stock:");
        bookStore.showBooks();
        bookStore.sale(l1, c1);
        System.out.println("Stock after selling:");
        bookStore.showBooks();
        System.out.println("Sales Volume:"+bookStore.SalesVolume);        
        bookStore.showClientsBooks(c1);

Should show this result:

Initial stock:
Author:H. Schildt   Title:"Java: The Complete Reference"   Base Price:80.0
Author:A. Christie   Title:"The Man in the Brown Suit"   Base Price:75.0
B. Antunes bought "Java: The Complete Reference", Tecnical Book of Computer Science- Java, for 72.0
Stock after selling:
Author:A. Christie   Title:"The Man in the Brown Suit"   Base Price:75.0
Sales Volume:72.0
B. Antunes bought: "UML Distilled". "The Man in the Brown Suit".

The only part that i cant do is the last line, showing the products that each client has bought, i was thinking of making an class that contained a string with the clients name and an arraylist of a book class, and then having an array list of that class for each client, but i'm not sure how to make this and theres probably a better way, Thanks

edit: i have this classes: class book class tecnicalbook extends book class adventurebook extends book

class client class regular extends client class frequent extends client class premium extends client

and i have the bookstore class where i have an array list of book and client objects.