An Interesting Problem #1

Main.java

package org.qianq;

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

/**
 * An enum containing several brands of planes.
 */
enum PlaneBrands {
    AIRBUS, BOEING, COMAC
}

/**
 * An interface containing several critical methods for a vehicle.
 */
interface Vehicle {
    /**
     * Get the ID of the current vehicle.
     * @return the ID of the vehicle
     */
    String getId();

    /**
     * Get the name of the current vehicle.
     * @return the name of the vehicle
     */
    String getName();

    /**
     * Get the capacity (the maximum number of people onboard) of the current vehicle.
     * @return the capacity of the vehicle
     */
    int capacity();

    /**
     * Make the vehicle transport a certain number of people from the departure to the destination.
     * @param people the number of people to transport
     * @param departure the departure location
     * @param destination the destination location
     */
    void transport(int people, String departure, String destination);

    /**
     * Get the information of the current vehicle.
     * @return the information of the vehicle, in form of "Vehicle [ID]: [Name]"
     */
    default String getInfo() {
        return String.format("Vehicle %s: %s", getId(), getName());
    }
}

class Plane implements Vehicle {
    /**
     * The current ID number.
     */
    private static int currentId = 0;

    /**
     * The ID of the plane.
     */
    private String id;
    /**
     * The name of the name.
     */
    private String name;
    /**
     * The maximum number of people that can be onboard.
     */
    private int capacity;
    /**
     * The brand of the plane.
     */
    private PlaneBrands planeBrand;
    /**
     * The cost to fly the plane once.
     */
    private int cost;
    /**
     * The price of a ticket.
     */
    private int ticket;

    public Plane(String name, int capacity, PlaneBrands planeBrand, int cost, int ticket) {
        this.id = switch (planeBrand) {
            case AIRBUS -> String.format("P%03d-A", ++currentId);
            case BOEING -> String.format("P%03d-B", ++currentId);
            case COMAC -> String.format("P%03d-C", ++currentId);
        };
        this.name = name;
        this.capacity = capacity;
        this.planeBrand = planeBrand;
        this.cost = cost;
        this.ticket = ticket;
    }

    public String getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public int capacity() {
        return capacity;
    }

    public void transport(int people, String departure, String destination) {
        System.out.printf("fly %d people from %s to %s\n", people, departure, destination);
    }

    public PlaneBrands getPlaneBrand() {
        return planeBrand;
    }

    public int getCost() {
        return cost;
    }

    public int getTicket() {
        return ticket;
    }
}

/**
 * A company in operation.
 */
class Company {
    /**
     * The name of the company.
     */
    private String name;
    /**
     * How much money the company has.
     */
    private int balance = 10000;

    public Company(String name) {
        this.name = name;
    }

    /**
     * Gain money.
     * @param amount amount of money the company gained
     */
    void gain(int amount) {
        balance += amount;
    }

    /**
     * Spend money.
     * @param amount amount of money the company spent
     */
    void spend(int amount) {
        balance -= amount;
    }

    public int getBalance() {
        return balance;
    }
}


/**
 * A company in air transport.
 */
class TransportCompany extends Company {
    /**
     * The planes that the company has.
     */
    public ArrayList<Plane> planes = new ArrayList<>();

    public TransportCompany(String name) {
        super(name);
    }

    /**
     * Show all the planes that the company has, in ascending order by capacity.
     */
    public void showVehicles() {
        boolean swapped;
        do {
            swapped = false;
            for (int i = 0; i < planes.size() - 1; i++) {
                if (planes.get(i).capacity() > planes.get(i + 1).capacity()) {
                    Plane temp = planes.get(i);
                    planes.set(i, planes.get(i + 1));
                    planes.set(i + 1, temp);
                    swapped = true;
                }
            }
        } while (swapped);

        for (Plane plane : planes) {
            System.out.printf("Plane %s: %s (brand: %s)\n", plane.getId(), plane.getName(), plane.getPlaneBrand());
        }
    }
}

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        System.out.println("Enter the name for the transport company:");
        String name = scanner.next();

        TransportCompany transportCompany = new TransportCompany(name);

        boolean running = true;
        while (running) {
            System.out.println("Menu:");
            System.out.println("1 - Add plane to the company.");
            System.out.println("2 - List the plane that the company currently holds.");
            System.out.println("3 - Call for a transport job.");
            System.out.println("4 - Show how many money the company has.");
            System.out.println("5 - Exit");

            String choice = scanner.next();

            switch (choice) {
                case "1" -> {
                    System.out.print("Enter a name for the plane: ");
                    String planeName = scanner.next();
                    System.out.print("Enter a capacity for the plane: ");
                    int capacity = scanner.nextInt();
                    System.out.print("Enter a brand for the plane: ");
                    boolean valid = true;
                    String brandString = scanner.next().toUpperCase();
                    PlaneBrands planeBrand = null;
                    switch (brandString) {
                        case "AIRBUS" -> planeBrand = PlaneBrands.AIRBUS;
                        case "BOEING" -> planeBrand = PlaneBrands.BOEING;
                        case "COMAC" -> planeBrand = PlaneBrands.COMAC;
                        default -> valid = false;
                    }
                    if (!valid) {
                        System.out.println("Plane Brand Invalid!");
                        break;
                    }
                    System.out.print("Enter the cost to fly the plane: ");
                    int cost = scanner.nextInt();
                    System.out.print("Enter the price of a ticket: ");
                    int ticket = scanner.nextInt();

                    Plane plane = new Plane(name, capacity, planeBrand, cost, ticket);
                    transportCompany.planes.add(plane);
                }
                case "2" -> transportCompany.showVehicles();
                case "3" -> {
                    System.out.print("Enter the ID of the plane you want to fly: ");
                    String id = scanner.next();

                    Plane plane = null;
                    for (Plane p : transportCompany.planes) {
                        if (p.getId().equalsIgnoreCase(id)) {
                            plane = p;
                            break;
                        }
                    }
                    if (plane == null) {
                        System.out.println("The ID you entered cannot be found!");
                        break;
                    }

                    System.out.print("Enter the number of people onboard: ");

                    int people = -1;
                    boolean valid = false;
                    while (!valid) {
                        try {
                            people = scanner.nextInt();
                        } catch (InputMismatchException e) {
                            scanner.next();
                            System.out.println("The number you entered is in a wrong format, retry.");
                            continue;
                        }
                        valid = true;
                    }

                    if (people > plane.capacity()) {
                        System.out.println("The plane cannot fit that much people!");
                        break;
                    }

                    System.out.print("Enter the departure place of the plane: ");
                    String departure = scanner.next();
                    System.out.print("Enter the destination place of the plane: ");
                    String destination = scanner.next();

                    plane.transport(people, departure, destination);

                    transportCompany.spend(plane.getCost());
                    transportCompany.gain(plane.getTicket() * people);
                }
                case "4" -> System.out.printf("The company currently has %d $\n", transportCompany.getBalance());
                case "5" -> running = false;
                default -> System.out.println("Invalid choice!");
            }
        }
    }
}