import java.io.*;
import java.util.*;

public abstract class Account {

protected static AccountNumber accountNumber;
protected Customer customer = null; // not to be used yet

public abstract MeterNumber[] getMeterNumbers();
public abstract boolean exists(String meterNumber, String tariff);

public static Account load(Scanner sc) {
   while (sc.hasNextLine()) {
       AccountNumber accountNumber = AccountNumber.fromString(sc.nextLine());
       String kind = sc.next();
       sc.nextLine();
       if (kind.equals("D")) {
           return new DomesticAccount(sc, accountNumber);
       }   else {
               return new CommercialAccount(sc, accountNumber);
           }
      }    {
               return null;
           }
   }

}

import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Scanner;
import java.util.Set;
import java.util.TreeSet;


public class Testt {

    public static void main(String[] args) {


        Account.load(new Scanner("Accounts3.txt"));

        Map <AccountNumber, String> map1 = new HashMap <AccountNumber, String>();

        map1.put(Account.accountNumber, "hello");

        System.out.println(map1);

    }
}

Exception in thread "main" java.util.NoSuchElementException
    at java.util.Scanner.throwFor(Scanner.java:862)
    at java.util.Scanner.next(Scanner.java:1371)
    at Account.load(Account.java:20)
    at Testt.main(Testt.java:14)