I wrote this program to implement a shopping cart. It supports adding/removing items to the cart, viewing the current order, and completing the checkout process.

import java.util.Scanner;

public class Keychains1 {

    public static Scanner keyboard = new Scanner(System.in);
    public static boolean stay = true;


    public static void add_keychains() {
        System.out.println("ADD KEYCHAINS");
    }

    public static void remove_keychains() {
        System.out.println("REMOVE KEYCHAINS");
    }

    public static void view_order() {
        System.out.println("VIEW ORDER");
    }

    public static void checkout() {
        System.out.println("CHECKOUT");
        stay = false;
    }


    public static void main(String[] args) {

        int choice;     

        while (stay) {

            System.out.println("Ye Olde Keychain Shoppe");
            System.out.println();

            System.out.println("1. Add Keychains to Order");
            System.out.println("2. Remove Keychains from Order");
            System.out.println("3. View Current Order");
            System.out.println("4. Checkout");
            System.out.println();
            System.out.print("Please enter your choice: ");

            choice = keyboard.nextInt();

            System.out.println();

            if (choice == 1) {
                add_keychains();
            }
            else if (choice == 2) {
                remove_keychains();
            }
            else if (choice == 3) {
                view_order();
            } 
            else if (choice == 4) {
                checkout();
            }
            else {
                System.out.println("Error. Please choose again.");
            }
            System.out.println();
        }

    }
}