Looping the wrong way?

Question

The assignment for my class asks me to create a program that tells a supermarket which customer, on a daily basis, has spent the most money in the store. The program must find this customer and display their name.

Goals of assignment - To work with multiple classes, work with ArrayLists and apply the knowledge gained.

My question:

1. How should I loop my two output statements in my main class? Is that right in my main method? I need it to loop until the sentinel is used.
2. How is this going to affect my sentinel?
3. What type of questions should I be asking myself when dealing with loops? I'd like to think I'm overthinking this portion.

I really want to understand what I am doing here, so any help in the right direction would be appreciated! Thanks, in advance, for taking the time to help me out!

import java.util.Scanner;

public class main {

public static void main(String[] args) {

    System.out.println("* * * * * THE SUPERMARKET * * * * *");
    System.out.println("       Written by Nate Irwin");
    System.out.println();

    double finalTotal = -1;
    String anAccountName;

    Scanner input = new Scanner(System.in);
    Store store = new Store();

    do {
        System.out.println("Enter the customer name: ");
        if(input.hasNextLine()){
            anAccountName = input.nextLine();
            System.out.println("Enter customer total price, hit 0 to QUIT: ");
            finalTotal = input.nextDouble();
            store.addAccount(anAccountName, finalTotal);
            System.out.println();
        }
    } while (finalTotal != 0);

    System.out.println(store.getHighestCustomerTotal() + " has spent the most with us today!");
}
}

Store class:

import java.util.ArrayList;

public class Store {
    // Creates an ArrayList.
    private ArrayList<CustomerAccount> accounts = new    ArrayList<CustomerAccount>();

    //
    public void addAccount(String anAccountName, double finalTotal) {
        accounts.add(new CustomerAccount(anAccountName, finalTotal));
    }

    // Gets the HIGHEST customer total.
    public String getHighestCustomerTotal() {

        CustomerAccount highest = accounts.get(0);

        for (int i = 1; i < accounts.size(); i++) {
            if (accounts.get(i).getTotal() > highest.getTotal())
            {
                highest = accounts.get(i);
            }
        }

        return highest.getAccountName();
    }

}

CustomerAccount class:

public class CustomerAccount {
    // Variables defined to this class.
    private String accountName;
    private double total;

    // Constructor.
    public CustomerAccount(String anAccountName, double finalTotal) {
        accountName = anAccountName;
        total = finalTotal;
    }

    // Gets total from each customer.
    public double getTotal() {
        return total;
    }

    // Gets a customer's name.
    public String getAccountName() {
        return accountName;
    }
}

Answer 1

Your loop in main:

• Doesn't really use the data you type in... One would expect this data to be used to create CustomerAccount instances
• Has a completely unnecessary while(Condition) test at the end. This kind of loop is normally done with a While True and some test in the loop breaks out of the loop.

In getHighestCustomerTotal()

• you can use a more "modern" form of the for() where you iterate elements of the list directly instead of iterating the index.

Answer 2

I think your approach is fine, it gets the job done.

I'm not too sure what you're asking by saying how should you loop the two output statements, followed by if it should be in the main method. From what I understand, and by looking at your code, running this input loop is perfectly fine from the main class. The do-while is fine although I'd move the first 'introductory' output outside the loop so you don't see it every time the loop reiterates. Also, I notice you're not actually calling/instantiating the Store class in your main method, there's no data being added to the Store class for when it iterates through the accounts ArrayList.

As far as the answer that stated a more "modern" approach, I think the for loop you used is fine. I think the person was referring to the for-each loop. It doesn't really matter how you loop through it with the little amount of data you have.

There's some error in the logic for that loop. The getHighestCustomerTotal() is referencing an empty accounts ArrayList. You declared an ArrayList within the Store class and tried to loop through it but it's empty unless you called the addAccount() method from your main method at some point, so you'd need some error checking on that.