How to access an array using a private static void method

Question

I am a beginner trying to program a train booking system which has 8 seats and requires the user to input various letters in order to execute a method. I am struggling to create a method through a private static void which when the user enters ‘E’ It shows all the empty seats through an array.

Here is the code that I have currently done so far:

package trainbookingsystem;

import java.util.Scanner;

public class Trainbookingsystem {           

    static final int NUMBER_OF_ROOMS = 8;

    public static void main(String[] args) {

        int [] Train = new int [NUMBER_OF_ROOMS];

          //Display an welcome and introduction to program

          //repeat
          Scanner in = new Scanner(System.in);
          char choice;
          do
          {
                    //display a menu
                displayMenu();

                    //read a choice
                System.out.println("--------------------------------------------------");
                System.out.println("Enter a letter to select an option or (Q) to exit");
                System.out.println("--------------------------------------------------");
                choice = in.next().toUpperCase().charAt(0);
                    //process that choice
                switch(choice)
                {
                    case 'Q' :System.out.println("");
                    break;

                    case 'E' : System.out.println("You chose empty room");
                        showEmptySeats(Train);
                    break;

                    default: System.out.println("You enetered an invalid choice");
                }

          //until the user presses 'Q', while choice is not 'Q'
          } while (choice != 'Q');

          //Exit anf Farewell
          System.out.println("Thank you for using our train booking system!");

    }



    private static void displayMenu() {
        System.out.println("|Welcome to the Train booking system|");
                System.out.println("*Use the following guide to naviagte through the program*");
                System.out.println("---------------------------------------------------------");
                System.out.println("| A |Add customer to seat");
                System.out.println("| V |View all seats");
                System.out.println("| E |Display Empty seats");
                System.out.println("| D |Delete customer from seat");
                System.out.println("| F |Find the seat for a given customers name");
                System.out.println("| S |Store program data in to file");
                System.out.println("| L |Load program data in to file");
                System.out.println("| O | View seats Ordered alphabetically by name");

    }

    private static void showEmptySeats(int[] someArray  ) {
        //Go through train seats array
        // if a seat is empty
            int a = someArray[4];
            //dsiplay it


    }    
}

You never set anything in that array, why would you expect it to have some values? — Amongalen, Mar 04 '20 at 10:33
Btw. By convention variable names in Java start with lowercase letter. — Amongalen, Mar 04 '20 at 10:33
Just FYI: Your methods have no return type (`void`) and you are [accessing them in a `static` way](https://stackoverflow.com/questions/2671496/java-when-to-use-static-methods) (directly from the main method). These two keywords are irrelevant to your problem. — bkis, Mar 04 '20 at 10:34

Arvind Kumar Avinash · Answer 1 · 2020-03-04T10:59:53.603

Note that uninitialized indices in an int array will have a value of 0. You can put 1 into the indices (seats) which get occupied. Just for the demo, I have reserved seat no. 0, 3 and 7 by putting 1 into them. Inside showEmptySeats, I have checked the train array for the indices which have 0 (means empty).

import java.util.Scanner;    

public class Trainbookingsystem {
    static final int NUMBER_OF_ROOMS = 8;

    public static void main(String[] args) {

        int [] train = new int [NUMBER_OF_ROOMS];
        train[0]=1;
        train[3]=1;
        train[7]=1;

        //Display an welcome and introduction to program

        //repeat
        Scanner in = new Scanner(System.in);
        char choice;
        do
        {
            //display a menu
            displayMenu();

            //read a choice
                System.out.println("--------------------------------------------------");
            System.out.println("Enter a letter to select an option or (Q) to exit");
                System.out.println("--------------------------------------------------");
            choice = in.next().toUpperCase().charAt(0);
            //process that choice
            switch(choice)
            {
                case 'Q':
                    System.out.println("");
                    break;

                case 'E':
                    System.out.println("You chose empty room");
                    showEmptySeats(train);
                    break;

                default:
                    System.out.println("You enetered an invalid choice");
            }

        //until the user presses 'Q', while choice is not 'Q'
        } while (choice != 'Q');

        //Exit anf Farewell
        System.out.println("Thank you for using our train booking system!");

    }

    private static void displayMenu() {
        System.out.println("|Welcome to the Train booking system|");
        System.out.println("*Use the following guide to naviagte through the program*");
        System.out.println("---------------------------------------------------------");
        System.out.println("| A |Add customer to seat");
        System.out.println("| V |View all seats");
        System.out.println("| E |Display Empty seats");
        System.out.println("| D |Delete customer from seat");
        System.out.println("| F |Find the seat for a given customers name");
        System.out.println("| S |Store program data in to file");
        System.out.println("| L |Load program data in to file");
        System.out.println("| O | View seats Ordered alphabetically by name");
    }

    private static void showEmptySeats(int[] train) {
        for(int i = 0;i<train.length;i++) {
            if(train[i]==0) {
                System.out.println("Seat no. "+i+" is empty");
            }
        }
    }
}

A sample run:

|Welcome to the Train booking system|
*Use the following guide to naviagte through the program*
---------------------------------------------------------
| A |Add customer to seat
| V |View all seats
| E |Display Empty seats
| D |Delete customer from seat
| F |Find the seat for a given customers name
| S |Store program data in to file
| L |Load program data in to file
| O | View seats Ordered alphabetically by name
--------------------------------------------------
Enter a letter to select an option or (Q) to exit
--------------------------------------------------
E
You chose empty room
Seat no. 1 is empty
Seat no. 2 is empty
Seat no. 4 is empty
Seat no. 5 is empty
Seat no. 6 is empty
|Welcome to the Train booking system|
*Use the following guide to naviagte through the program*
---------------------------------------------------------
| A |Add customer to seat
| V |View all seats
| E |Display Empty seats
| D |Delete customer from seat
| F |Find the seat for a given customers name
| S |Store program data in to file
| L |Load program data in to file
| O | View seats Ordered alphabetically by name
--------------------------------------------------
Enter a letter to select an option or (Q) to exit
--------------------------------------------------

I hope, you should be able to proceed from here. Feel free to comment in case you need any further help.

How to access an array using a private static void method

1 Answers1