Выдает исключение и не проверяет на пустое значение

package com.javarush.task.task20.task2002;

import java.io.*;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.List;

/*
Читаем и пишем в файл: JavaRush
*/
public class Solution {
    public static void main(String[] args) {
        //you can find your_file_name.tmp in your TMP directory or fix outputStream/inputStream according to your real file location
        //вы можете найти your_file_name.tmp в папке TMP или исправьте outputStream/inputStream в соответствии с путем к вашему реальному файлу
        try {
            File your_file_name = File.createTempFile("your_file_name", null);
            OutputStream outputStream = new FileOutputStream(your_file_name);
            InputStream inputStream = new FileInputStream(your_file_name);

            JavaRush javaRush = new JavaRush();
            //initialize users field for the javaRush object here - инициализируйте поле users для объекта javaRush тут


            User user1 = new User();
            user1.setFirstName("Толик");
            user1.setLastName("Алкоголик");
            GregorianCalendar calendar = new GregorianCalendar(1954, 12, 12);
            user1.setBirthDate(calendar.getTime());
            user1.setCountry(User.Country.UKRAINE);
            user1.setMale(true);
            javaRush.users.add(user1);

            User user2 = new User();
            user2.setFirstName("Лелик");
            user2.setLastName("Анаболик");
            calendar = new GregorianCalendar(1967, 10, 01);
            user2.setBirthDate(calendar.getTime());
            user2.setCountry(User.Country.RUSSIA);
            user2.setMale(false);
            javaRush.users.add(user2);

            User user3 = new User();
            user3.setFirstName("Болик");
            user3.setLastName("АнаЛелик");
            calendar = new GregorianCalendar(1954, 11, 05);
            user3.setBirthDate(calendar.getTime());
            user3.setCountry(User.Country.OTHER);
            user3.setMale(false);
            javaRush.users.add(user3);

            javaRush.save(outputStream);
            outputStream.flush();

            JavaRush loadedObject = new JavaRush();
            loadedObject.load(inputStream);
            //check here that javaRush object equals to loadedObject object - проверьте тут, что javaRush и loadedObject равны
            if (javaRush.equals(loadedObject) && (javaRush.hashCode() == loadedObject.hashCode()))
                System.out.println("Есть совпадение");

            outputStream.close();
            inputStream.close();

        } catch (IOException e) {
            //e.printStackTrace();
            System.out.println("Oops, something wrong with my file");
        } catch (Exception e) {
            //e.printStackTrace();
            System.out.println("Oops, something wrong with save/load method");
        }
    }

    public static class JavaRush {
        public List<User> users = new ArrayList<>();

        public void save(OutputStream outputStream) throws Exception {
            //implement this method - реализуйте этот метод
            OutputStreamWriter outputStreamWriter = new OutputStreamWriter(outputStream);
            if (!users.isEmpty()){
                for (User user : users)
                {
                    outputStreamWriter.write(user.getFirstName() + " " + user.getLastName() + " " +
                            Long.toString(user.getBirthDate().getTime()) + " " + user.getCountry().getDisplayedName() + " " + user.isMale() + "\n");
                }
                outputStreamWriter.flush();
            }
        }

        public void load(InputStream inputStream) throws Exception {
            //implement this method - реализуйте этот метод
            BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));

           if (reader.ready()){
               while (reader.ready())
               {
                   String line = reader.readLine();
                   String[] strings = line.split(" ");

                   User user = new User();
                   user.setFirstName(strings[0]);
                   user.setLastName(strings[1]);
                   user.setBirthDate(new Date(Long.parseLong(strings[2])));
                   user.setCountry(User.Country.valueOf(strings[3]));
                   user.setMale(Boolean.parseBoolean(strings[4]));
               }
           } else this.users = null;
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;

            JavaRush javaRush = (JavaRush) o;

            return users != null ? users.equals(javaRush.users) : javaRush.users == null;

        }

        @Override
        public int hashCode() {
            return users != null ? users.hashCode() : 0;
        }
    }
}