Question

I think there are a few fundamental problems with my code here. I’m not too familiar with the java syntax, so I’m not too sure where I’ve gone wrong. Any help would be greatly appreciated.

I have tried to use a constructor in the middle, and a few accessors towards the bottom, but I think I have over-complicated it for myself.

import java.util.Scanner;    
public class FerryBooking {

    public static void main(String args[]){
        class VehicleBooking {
            private String booking_ID = new String("");
            private String registration = new String("");
            private String make_model = new String("");
            private int number_passengers = 1;
            private boolean insurance_choice = false;
            private boolean insurance_flag = false;

            public static final int booking_fee= 100;
            public static final int extra_passenger = 50;
            public static final int insurance_fee = 50;

            VehicleBooking() {
                Scanner input = new Scanner(System.in);
                Scanner scan = new Scanner(System.in);

                System.out.print("Enter booking ID");
                booking_ID = input.next();
                System.out.print("Enter registration number");
                registration = input.next();
                System.out.print("Enter vehicle make/model");
                make_model = input.next();
                System.out.print("Enter number of passengers");
                number_passengers = scan.nextInt();
            }

            public String getBookingID(){
                return booking_ID;
            }
            public String getRegistration(){
                return registration;
            }
            public String getMakeModel(){
                return make_model;
            }
            public int getPassengers(){
                return number_passengers;
            }
            public boolean getInsurance(){
                return insurance_choice;
            }
            public boolean addInsurance(){
                insurance_choice = true;
                if (insurance_flag = false) {
                    insurance_flag = true;
                    return true;
                } else if (insurance_flag = true) {
                    return false;
                }
                return true;
            }
            public double getBookingFee(){
                int final_cost = booking_fee + (getPassengers()*extra_passenger);
                if (insurance_choice = true){
                    final_cost = final_cost + insurance_fee;
                }
                return final_cost;
            }
        }
    }
}

–EDIT–

I have re-written a lot of the code, and sized it down to where my big issue was; the constructor. However I am getting an error related to the constructor with the code provided to me.

import java.util.Scanner;

public class VehicleBooking {

    private String booking_ID = "";
    private String registration = "";
    private String make_model = "";
    private int number_passengers = 1;
    private boolean insurance_choice = false;

    public static final int BOOKING_FEE= 100;
    public static final int EXTRA_PASSENGER = 50;
    public static final int INSURANCE_FEE = 50;

    public VehicleBooking(String booking_ID1, String registration1,  String make_model1, int number_passengers1) {

        /** Initialise the variables **/
        booking_ID = booking_ID1;
        registration = registration1; 
        make_model = make_model1;
        number_passengers = number_passengers1;
    }

    public static void main(String args[]) {
        VehicleBooking vb = new VehicleBooking(booking_ID1, registration1, make_model1, number_passengers1);
    }       
}

Answer 1

First don’t initialize a String like the one below: –

private String booking_ID = new String("");

Rather use String.valueOf() or just assign an empty string to variable: –

private String booking_ID = "";

Second, make a habit to declare your CONSTANTS with UPPER_CASE letter: –

public static final int BOOKING_FEE = 100;

Third, take a look at your constructor: –

    VehicleBooking()  {
        Scanner input = new Scanner(System.in);
        Scanner scan = new Scanner(System.in);

        System.out.print("Enter booking ID");
        booking_ID = input.next();
        System.out.print("Enter registration number");
        registration = input.next();
        System.out.print("Enter vehicle make/model");
        make_model = input.next();
        System.out.print("Enter number of passengers");
        number_passengers = scan.nextInt();
    }

You should never do I/O operation in your constructor.. Constructors are used to initialize the state of the object. It’s sole purpose is to initialize.

For I/O purpose, make different method readInput() and call it after your object is created..

Another thing: – Here’s your if-else-if block you have used..

         if (insurance_flag = false) {
             insurance_flag = true;
             return true;
         } else if (insurance_flag = true) {
             return false;
         }

In this code, your if is always false and your else if is always true.. Because you are actually assigning these values to your insurance_flag.. You should use == for comparison purpose..

So, use if (insurance_flag == false).. In fact you don’t need to compare with a boolean literal…

just use: – if (!insurance_flag).. They are equivalent..

Ideally you should change that method containing your above if to the one below: –

       public boolean addInsurance(){
            boolean returnValue = !insurance_flag;
            insurance_flag = true;
            return returnValue;
       }

Because that is what your method is doing, but in an odd way..

You can also replace final_cost = final_cost + insurance_fee; with the below code: –

final_cost += insurance_fee;

By using it this way, final_cost will not be evaluated twice..

EDIT ** : –

Your constructor should look like this: –

public VehicleBooking(String bookingId, String registration, String makeModel, 
                      String numberOfPassengers)  {

    /** Initialize the instance variables **/
    /** this represent the reference to current object **/
    this.booking_ID = bookingId;
    this.registration = registration; 
    this.make_model = makeModel;
    this.number_passengers = numberOfPassengers;
}

So, you’re actually passing those values you read, into the constructor as parameter, and initializing your instance attributes, with those parameters..

I think this would clear your doubt..