帮我修改一下我的代码错误：帮我看看我这段代码有什么错误：int choice = readPosInt("Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): "); // Perform the selected action while (choice != 6) { switch (choice) { case 1: System.out.println("Total number of borrowed books: " + Library.totalBorrowedBooks(null)); break; case 2: System.out.print("Type the user role (lender:1 borrower:2): "); int role = readPosInt(null); if (role == 1) { System.out.print("Enter the name of the user: "); String name = readLine(name); System.out.print("Enter the initial number of lent books: "); int numBooks = readPosInt(null); Lender lender = new Lender(name, numBooks); Library.addUser(lender); System.out.println("Lender "" + name + "" lending " + numBooks + " book(s) has been added."); } else if (role == 2) { System.out.print("Enter the name of the user: "); String name = readLine(name); System.out.print("Enter the initial number of borrowed books: "); int numBooks = readPosInt(null); Borrower borrower = new Borrower(name, numBooks); Library.addUser(borrower); System.out.println("Borrower "" + name + "" borrowing " + numBooks + " book(s) has been added."); } else { System.out.println("Unknown user role!"); } break; case 3: System.out.print("Enter the name of the user: "); String username = input.nextLine(); try { int numBorrowed = Library.totalBorrowedBooks(username); System.out.println(username + " borrows " + numBorrowed + " book(s)."); } catch (UnknownUserException e) { System.out.println("User " + username + " unknown."); } break; case 4: try { System.out.print("Enter the name of the user: "); String name = input.nextLine(); System.out.print("Enter the number of books: "); int num = input.nextInt(); input.nextLine(); library.moreBook(username, role); } catch (UnknownUserException e) { System.out.println("User " + username + " unknown."); } break; case 5: System.out.print("Enter the name of the user: "); username = input.next(); System.out.print("Enter the number of books: "); int numBooks = input.nextInt(); library.moreBook(username, -numBooks); // simulate decreasing books break; case 6: System.out.println("Goodbye!"); System.exit(0); break; }

在这段代码中，有几个错误需要修改：

1. 在第6行，readPosInt方法的参数为"Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): "，应该改为null。

2. 在第17行，Lender和Borrower的构造函数需要传入参数name和numBooks，应该改为lender和borrower。

3. 在第31行，input.nextLine()应该放在int role = readPosInt(null);的后面。

4. 在第37行，library应该改为Library。

5. 在第44行，input.next()应该改为input.nextLine()。

修改后的代码如下：

int choice = readPosInt(null);
// Perform the selected action
while (choice != 6) {
    switch (choice) {
        case 1:
            System.out.println("Total number of borrowed books: " + Library.totalBorrowedBooks(null));
            break;
        case 2:
            System.out.print("Type the user role (lender:1 borrower:2): ");
            int role = readPosInt(null);
            if (role == 1) {
                System.out.print("Enter the name of the user: ");
                String name = readLine(null);
                System.out.print("Enter the initial number of lent books: ");
                int numBooks = readPosInt(null);
                Lender lender = new Lender(name, numBooks);
                Library.addUser(lender);
                System.out.println("Lender " + name + " lending " + numBooks + " book(s) has been added.");
            } else if (role == 2) {
                System.out.print("Enter the name of the user: ");
                String name = readLine(null);
                System.out.print("Enter the initial number of borrowed books: ");
                int numBooks = readPosInt(null);
                Borrower borrower = new Borrower(name, numBooks);
                Library.addUser(borrower);
                System.out.println("Borrower " + name + " borrowing " + numBooks + " book(s) has been added.");
            } else {
                System.out.println("Unknown user role!");
            }
            break;
        case 3:
            System.out.print("Enter the name of the user: ");
            String username = input.nextLine();
            try {
                int numBorrowed = Library.totalBorrowedBooks(username);
                System.out.println(username + " borrows " + numBorrowed + " book(s).");
            } catch (UnknownUserException e) {
                System.out.println("User " + username + " unknown.");
            }
            break;
        case 4:
            try {
                System.out.print("Enter the name of the user: ");
                String name = input.nextLine();
                System.out.print("Enter the number of books: ");
                int num = input.nextInt();
                input.nextLine();
                Library.moreBook(name, num);
            } catch (UnknownUserException e) {
                System.out.println("User unknown.");
            }
            break;
        case 5:
            System.out.print("Enter the name of the user: ");
            username = input.nextLine();
            System.out.print("Enter the number of books: ");
            int numBooks = input.nextInt();
            input.nextLine();
            Library.moreBook(username, -numBooks); // simulate decreasing books
            break;
        case 6:
            System.out.println("Goodbye!");
            System.exit(0);
            break;
    }
    choice = readPosInt(null);
}