Buying Simulator (has a compilation error)

Buyign Simulator

package askhsh7;

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

public class Askhsh7 {

    public void static main(String[] args) {
        int[] passwords = {1, 2, 3, 4, 5, 6};
        int[] quantities = {22, 5, 2, 4, 80, 1};
        String[] ITEMS = {"ITEM1", "ITEM2", "ITEM3", "ITEM4", "ITEM5", "ITEM6"};
        int[] prices = {100, 50, 40, 22, 39, 89};
        Scanner scan = new Scanner(System.in);
        String answ;
        int pass, FLAG = 0;
        Invoice Customer = new Invoice();
        do {
            if (FLAG == 0) {
                System.out.println("DO YOU WISH TO BUY AN ITEMS ? IF YOU WANT TYPE  'yes' ELSE TYPE 'no' ");
                answ = scan.nextLine();
                if (answ == "no") {
                    break;
                }
            }
            System.out.println("CHOOSE THE PASSWORD THAT REPRESENTS THE ITEM YOU WANT");
            System.out.println(ITEMS);
            System.out.println(passwords);
            pass = scan.nextInt();
            if (Chek4Availability(quantities, pass) == null) {
                do {
                System.out.println("CHOOSE THE PASSWORD THAT REPRESENTS THE ITEM YOU WANT");
                System.out.println(ITEMS);
                System.out.println(passwords);
            pass = scan.nextInt();
                }while(Chek4Availability(quantities, pass) != null);
            }
            Customer.ListingItems(pass, ITEMS);
            Customer.Price(prices[pass - 1]);
            System.out.print("DO YOU WANT TO BUY AN NEW ITEM ? TYPE  'yes' ELSE TYPE 'no'");
            answ = scan.nextLine();
            FLAG += 1;
        } while (answ == "yes");
        System.out.println("TYPE IN YOUR NAME :");
        String name = scan.nextLine();
        Customer.Name(name);
        System.out.println("TYPE IN YOUR SHIPPING ADDRESS");
        String address = scan.nextLine();
        Customer.Address(address);
        System.out.println("TYPE IN YOUR BILLING ADDRESS");
        String Baddress = scan.nextLine();
        Customer.Baddress(address);
        Customer.Payment(FLAG);
    }

    public static int[] Chek4Availability(int[] quant, int pass) {
        if (quant[pass - 1] > 0 && pass >= 0 && pass <= 6) {
            System.out.println("the item you want is available");
            quant[pass - 1] += -1;
        } else {
            System.out.println("the item you want is not available");
            return null;
        }
        return quant;
    }

    public class Invoice {

        int totalprice = 0, X;
        ArrayList invoice = new ArrayList();
        ArrayList<String> items = new ArrayList();
        Scanner scan = new Scanner(System.in);
        public Invoice() {

        }

        public void Price(int tempoprice) {
            totalprice = tempoprice;
            invoice.set(0, totalprice);
        }

        public void Name(String temponame) {
            invoice.add(temponame);
        }

        public void Address(String address) {
            invoice.add(address);
        }

        public void Baddress(String address) {
            invoice.add(address);
        }

        public void ListingItems(int pass, String[] itemslist) {
            items.add(itemslist[pass - 1]);
        }

        public void Payment( int totalitems) {
            System.out.println("YOUR TOTAL PRICE IS " + totalprice);
            System.out.println("TYPE IN YOUR PAYMENT AMONT");
            int payment = scan.nextInt();
            if (totalprice - payment < 0) {
                System.out.println("YOUR PAYMENT WAS NOT SUCCES FULL AMOUNT DUE :" + (totalprice - payment));
            } else {
                System.out.println("YOUR PAYMENT WAS SUCCESFULL THANK YOU FOR PREFERING OUR SERVICES");
                System.out.println("INVOICE :" + "\n" + "TOTALPRICE :  " + invoice.get(0) + "\n" + "SUM OF ITEMS :  " + totalitems + "\n"
                        + "SHIPPING ADDRESS :  " + invoice.get(1) + "\n" + "BILLING ADDRESS" + invoice.get(2));
            }
        }

    }
}