错误：找不到或加载主类hfsmart.ShoppingCart原因：java.lang.ClassNotFoundException：hfsmart.ShoppingCart

Question

为什么显示：

  

错误：找不到或加载主类hfsmart.ShoppingCart
  原因：java.lang.ClassNotFoundException：hfsmart.ShoppingCart

我已经搜索过，但仍然不知道该怎么做。

我该怎么办？

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


public class ShoppingCart {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int shoppingType = 0;
        boolean flag = true;
        boolean memberStatus = false;
        String temp = "";
        String option = "";
        NonMember member;
        int input = 0;
        ArrayList<String> sellItems = new ArrayList<String>() {
            {
                add("Yogurt");
                add("Sugar");
                add("Butter");
                add("Chocolate");
                add("Bread");
            }
        };

        System.out.println("Welcome to Nono Mall");

        do {
            flag = false;
            System.out.print("Do you want to be a member? [y|n]: ");
            option = sc.nextLine();
            if (option.equalsIgnoreCase("y") || option.equalsIgnoreCase("n"))
                flag = true;
        } while (flag == false);

        if (option.equalsIgnoreCase("y")) {
            int memberNumber = (int) (Math.random() * 100 + 1);
            member = new Member(memberNumber);
            System.out.println("Your member number is " + memberNumber);
        } else {
            member = new NonMember();
        }

        System.out.println("\n\nBefore you shop, please choose your shopping cart");
        System.out.println("1. Shopping Carry Basket");
        System.out.println("2. Shopping Trolley");

        do {
            try {
                flag = true;
                System.out.print("Input: ");
                shoppingType = sc.nextInt();
            } catch (Exception e) {
                flag = false;
                sc.nextLine();
            }
        } while (shoppingType < 1 || shoppingType > 2 || flag == false);

        if (shoppingType == 1)
            member.cart = new Basket();
        else
            member.cart = new Trolley();

        do {
            try {
                flag = true;
                System.out.println("Shopping cart capacity: " + member.cart.capacity);
                System.out.println("1. Buy Item");
                System.out.println("2. View Item");
                System.out.println("3. Checkout");
                System.out.print("Input: ");
                input = sc.nextInt();
            } catch (Exception e) {
                flag = false;
            }

            switch (input) {
            case 1:
                System.out.println("\nChoose Items");
                System.out.println("==================");
                for (int i = 0; i < sellItems.size(); i++) {
                    System.out.println((i + 1) + ". " + sellItems.get(i));
                }
                int choose = 0, qtyTemp = 0;
                boolean flagItem = true;
                do {
                    flagItem = true;
                    try {
                        System.out.print("Choose :");
                        choose = sc.nextInt();
                    } catch (Exception e) {
                        flagItem = false;
                    }
                } while (flagItem == false || choose < 1 || choose > sellItems.size());

                do {
                    try {
                        flagItem = true;
                        System.out.print("How many items you want to buy? ");
                        qtyTemp = sc.nextInt();

                    } catch (Exception e) {
                        flagItem = false;
                    }
                } while (flagItem == false);
                member.addToCart(sellItems.get(choose - 1), qtyTemp);

                break;

            case 2:
                System.out.println("\nCurrent Item: ");
                System.out.println("================");
                for (int i = 0; i < member.cart.listBarang.size(); i++) {
                    System.out.println(member.cart.listBarang.get(i) + "      " + member.cart.listQty.get(i));
                }
                System.out.println();
                break;
            case 3:
                System.out.print("Please pay at cashier.. ");
                int totalItem = 0;
                for (int i=0;i<member.cart.listQty.size();i++) {
                    totalItem += member.cart.listQty.get(i);
                }

                if (member instanceof Member) {
                    System.out.println("Total item: " + totalItem);
                    ((Member) member).point = totalItem / 2;
                    System.out.println("You have discount " + ((Member) member).discount);
                    System.out.println("Your point now: " + ((Member) member).point);
                }
                break;
            }
        } while (input != 3 || flag == false);

    }

}