Action 4: increasing the number of books of a given user. When the user of the software specifies action 4, your program must ask the user to type the name of a user, and a number of books, and the program then uses that number to increase the number of books lent or borrowed by the user. Then the program goes back to the main menu. For example: Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3 Enter the name of the user: Anna Anna borrows -5 book(s). Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 4 Enter the name of the user: Anna Enter the number of books: 2 Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3 Enter the name of the user: Anna Anna borrows -7 book(s). Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3 Enter the name of the user: Bob Bob borrows 10 book(s). Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 4 Enter the name of the user: Bob Enter the number of books: 2 Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3 Enter the name of the user: Bob Bob borrows 12 book(s). Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): If the name of the user is wrong, then an UnknownUserException exception will be thrown by the Library object. The code of the main method of your CLI class must catch this exception, print the error message from the exception object, and then it just goes back to printing the menu of actions (by just going back to the beginning of the while loop). For example (where 4, aaaa, and 2 are inputs from the user): Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 4 Enter the name of the user: aaaa Enter the number of books: 2 User aaaa unknown. Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): Note that, even if a consumer is a borrower, the readPosInt method prevents the typed number of books from being negative. This means a borrower will never throw a NotALenderException. Nevertheless the code of the main method of your CLI class must handle this exception by printing the error message "BUG! This must never happen!" and immediately terminating the program using System.exit(1). For example (where 3, Bob, 4, Bob, and -15 are inputs from the user): Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3 Enter the name of the user: Bob Bob borrows 12 book(s). Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 4 Enter the name of the user: Bob Enter the number of books: -15 Positive integers only! Enter the number of books:

Sure, here's the updated code for the CLI class:

import java.util.Scanner;

public class CLI {

    private Library library;
    private Scanner scanner;

    public CLI(Library library) {
        this.library = library;
        this.scanner = new Scanner(System.in);
    }

    public void run() {
        while (true) {
            System.out.print("Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): ");
            int action = readPosInt();

            switch (action) {
                case 1:
                    System.out.println("Total number of books: " + library.getTotal());
                    break;
                case 2:
                    System.out.print("Enter the number of books to add: ");
                    int add = readPosInt();
                    library.add(add);
                    System.out.println("Total number of books: " + library.getTotal());
                    break;
                case 3:
                    System.out.print("Enter the name of the user: ");
                    String borrower = scanner.nextLine();
                    try {
                        int borrowed = library.get(borrower);
                        System.out.println(borrower + " borrows " + borrowed + " book(s).");
                    } catch (UnknownUserException e) {
                        System.out.println(e.getMessage());
                    }
                    break;
                case 4:
                    System.out.print("Enter the name of the user: ");
                    String lender = scanner.nextLine();
                    System.out.print("Enter the number of books: ");
                    int books = readPosInt();
                    try {
                        library.more(lender, books);
                        System.out.println(lender + " now lends " + library.get(lender) + " book(s).");
                    } catch (UnknownUserException e) {
                        System.out.println(e.getMessage());
                    }
                    break;
                case 5:
                    System.out.print("Enter the name of the user: ");
                    String borrower2 = scanner.nextLine();
                    System.out.print("Enter the number of books: ");
                    int books2 = readPosInt();
                    try {
                        library.less(borrower2, books2);
                        System.out.println(borrower2 + " now borrows " + library.get(borrower2) + " book(s).");
                    } catch (UnknownUserException e) {
                        System.out.println(e.getMessage());
                    } catch (NotALenderException e) {
                        System.out.println("BUG! This must never happen!");
                        System.exit(1);
                    }
                    break;
                case 6:
                    System.out.println("Goodbye!");
                    return;
                default:
                    System.out.println("Invalid action.");
                    break;
            }
        }
    }

    private int readPosInt() {
        while (true) {
            try {
                int num = Integer.parseInt(scanner.nextLine());
                if (num < 0) {
                    throw new NumberFormatException();
                }
                return num;
            } catch (NumberFormatException e) {
                System.out.print("Positive integers only! Enter a number again: ");
            }
        }
    }
}

I added a new case for action 4, where we prompt the user for the name of the user and the number of books to add. Then we call the `more` method on the library object with those parameters, catch any `UnknownUserException` exceptions that may be thrown, and print the appropriate message.

I also added an additional catch block for the `NotALenderException` that may be thrown in the `less` method. In this case, we print an error message and immediately terminate the program using `System.exit(1)`.

Let me know if you have any questions or concerns!