Can somebody help me whit the exeptions

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package com.codegym.task.task20.task2002; import java.io.*; import java.text.SimpleDateFormat; import java.util.ArrayList; import java.util.Date; import java.util.List; /* Reading and writing to a file: CodeGym */ public class Solution { public static void main(String[] args) { // You can find your_file_name.tmp in your TMP directory or adjust outputStream/inputStream according to your file's actual location try { File yourFile = File.createTempFile("your_file_name", null); OutputStream outputStream = new FileOutputStream(yourFile); InputStream inputStream = new FileInputStream(yourFile); CodeGym codeGym = new CodeGym(); // Initialize users field for the codeGym object here codeGym.save(outputStream); outputStream.flush(); CodeGym loadedObject = new CodeGym(); loadedObject.load(inputStream); // Here check that the codeGym object is equal to the loadedObject object outputStream.close(); inputStream.close(); } catch (IOException e) { //e.printStackTrace(); System.out.println("Oops, something is wrong with my file"); } catch (Exception e) { //e.printStackTrace(); System.out.println("Oops, something is wrong with the save/load method"); } } public static class CodeGym { public List<User> users = new ArrayList<>(); public void save(OutputStream outputStream) throws Exception { // Implement this method PrintWriter outputLines = new PrintWriter ( outputStream ); if(users.isEmpty ()){ }if(!users.isEmpty ()){ for(User user : users){ //write first name if(user.getFirstName () == null){ outputLines.println ( "null" ); }else outputLines.println ( user.getFirstName () ); if(user.getLastName () == null){ outputLines.println ( "null" ); }else { outputLines.println ( user.getLastName () ); } //write birthday if(user.getBirthDate () == null){ outputLines.println ( "null" ); }else{ outputLines.println ( user.getBirthDate ()); } //write sex if(user.isMale ()){ outputLines.println ( "true" ); }else{ outputLines.println ( "false" ); } //write country if(user.getCountry () == null){ outputLines.println ( "null" ); }else{ outputLines.println ( user.getCountry ().getDisplayName () ); } outputLines.flush (); } } } public void load(InputStream inputStream) throws Exception { // Implement this method BufferedReader reader = new BufferedReader ( new InputStreamReader ( inputStream ) ); while(reader.ready ()) { User user = new User (); //write first name String firstName = reader.readLine (); if(firstName.equals ( "null" )){ user.setFirstName ( null ); }else { user.setFirstName (firstName); } //write last name String lastName = reader.readLine (); if(lastName.equals ( "null" )){ user.setLastName ( null ); }else { user.setLastName ( lastName ); } //write birthday String birthday = reader.readLine (); if(birthday.equals ( "null" )){ user.setBirthDate ( null ); }else{ user.setBirthDate (new SimpleDateFormat ( "dd-MMM-yyyy" ).parse ( birthday ) ); } //write sex String isMale = reader.readLine (); if(isMale.equals ( "true" )){ user.setMale ( true ); }else{ user.setMale ( false ); } //write country String country = reader.readLine (); if(country.equals ( "null" )){ user.setCountry ( null ); }else{ if(country.equals ( "United States" )){ user.setCountry ( User.Country.UNITED_STATES ); } if(country.equals ( "United Kingdom" )){ user.setCountry ( User.Country.UNITED_KINGDOM ); } if(country.equals ( "Other" )){ user.setCountry ( User.Country.OTHER ); } } users.add ( user ); } } @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; CodeGym codeGym = (CodeGym) o; return users != null ? users.equals(codeGym.users) : codeGym.users == null; } @Override public int hashCode() { return users != null ? users.hashCode() : 0; } } }

Implement the logic for file IO for the CodeGym class.
The file your_file_name.tmp can contain several CodeGym objects.
The main method exists just for you and is not involved in testing the solution.

Requirements:

The read/write logic in the save/load methods must work correctly when the users list is empty.
The read/write logic in the save/load methods must work correctly when the users list is not empty.
The Solution.CodeGym class should not support the Serializable interface.
The Solution.CodeGym class must be public.
The Solution.CodeGym class should not support the Externalizable interface.

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Ivaylo Trifonov

Level 22 , Madrid, Spain

3 November 2019, 18:27

Well, my friend, I struggled with this task, solved it with 26 attempts, and after 2-3 days of thinking and testing. Only 89 students solved it. In Your code : 1. In the save() method, there is no need to put some value (String "null" in Your case) if the value is already null, just make the check for null and then print the value if it is not null, else just nothing. 2. In the save() method, for the birthDate You need to pass a Date, but print a number (long) rather the Date itself. The date class has a method for it. It will help You later in the load() method to retrieve the value. The other way with the date format and parse always throws exceptions (different input of the date like 02/12/1997 or 2001-11-30 and the different locale that may be entered). 3. In the save() method, try to convert the isMale() method data to String and then make the check based on equality and print a String value also. 4. In the load() method, make a check before starting the while loop. You have to check if the users list is empty. 5. In the load() method, again, like in the save() method You only need to check if the value is not null and then (if is not of course) set it to the given variable (firstName, birthDate, etc.). 6. In the load() method, now You need to set a Date and for that, You have to convert (parse) the number value for the Date from the save() method. The rest of Your code seems to be good and working. I know that may look very complicated and frustrating but, if You concentrate on only one problem and work You way step by step it is not so scary :) In the end, this is what is programming for, problem-solving. For easy go-thru program code and detecting bugs, I recommend You to create User object and filling it with some test data. This way You can track the bugs and errors with simple debugging. I hope I helped You somehow. If You have some additional questions I will be glad to help.