I've been stuck on this for ages now.... Please help getting "Check why exception occures in the save/load methods."

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So this "clue" from the mentor does absolutely no good at helping me out. I haven't a clue what to do and I've been reading like crazy to try to figure this out and I all I keep reading everywhere is that it is 1000x easier and safer and better to just use serialization.... please help. Thanks in advance : )

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.

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 { PrintStream out = new PrintStream(outputStream); if (users.size()==0) { out.print("null"); } else { for (User u : users) { String firstName = u.getFirstName(); String lastName = u.getLastName(); String birthday = u.getBirthDate().toString(); String sex = u.isMale()? "true":"false"; String country = u.getCountry().toString(); out.print(firstName +","+ lastName +","+ birthday +","+ sex +","+ country); } } } public void load(InputStream inputStream) throws Exception { BufferedReader bR = new BufferedReader(new InputStreamReader(inputStream)); String in = bR.readLine(); if (!in.equals("null")) { String[] inStrings = in.split(","); String firstName = inStrings[0]; String lastName = inStrings[1]; String birthday = inStrings[2]; String sex = inStrings[3]; String country = inStrings[4]; User user = new User(); //Name user.setFirstName(firstName); user.setLastName(lastName); //Birthday SimpleDateFormat formatter = new SimpleDateFormat("EEEE, dd/MM/yyyy/hh:mm:ss"); Date parsedDate = formatter.parse(birthday); user.setBirthDate(parsedDate); //Sex if (sex.equals("true")) { user.setMale(true); } else { user.setMale(false); } //country if (country.equals("United States")) { user.setCountry(User.Country.UNITED_STATES); } if (country.equals("United Kingdom")) { user.setCountry(User.Country.UNITED_KINGDOM); } else { user.setCountry(User.Country.OTHER); } } } @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; } } }

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Guadalupe Gagnon

Level 37 , Tampa, United States

26 November 2019, 16:15

solution

The problem is that this code only works properly if there is none or one user in the list. In the save method the code loops through all the users and adds them to the file, the problem is they all end up on the same line. In the load method the code will successfully create one user, but it should continue creating users until all the users in the file have been successfully created. It should also be adding them to the users list. Tips: #1 Make sure to add a new line for each user saved to the file. The best way is to save the first user in the list manually, then each subsequent users save with a new line character at the beginning of the line:

if (users.size() > 0) {
   User temp = user.get(0);
   String firstName = temp.getFirstName();
   String lastName = temp.getLastName();
   String birthday = temp.getBirthDate().toString();
   String sex = temp.isMale()? "true":"false";
   String country = temp.getCountry().toString();
   out.print(firstName +","+ lastName +","+ birthday +","+ sex +","+ country);
    for(int i = 1; i < users.size(); i++{
      //copy above code other than output line
      out.print("\n" + firstName +","+ lastName +","+ birthday +","+ sex +","+ country);
   }
}

This guarantees no empty lines are added #2 Using the above tips, change lines 65 and 65 to:

String in;
while ((in = bR.readLine()) != null) {
   // code to create a user and add it to the list
}

This is a loop that will continue reading until no more data is available. #3 You don't need lines 93-101. This will work the same way:

user.setCountry(User.Country.valueOf(country));

Jason

Level 26 , Rancho Cucamonga, United States

26 November 2019, 19:44

Okay I did all those things and I am still getting the same fail message. I was trying everything I could think of after that like tried closing the streams to see if there was something that wasn't happening leaving them open. I tried clearing the users arraylist to see if that had something to do with it. I tried your way of populating "country" and my way with all the different combinations you can think of and I am still not getting anywhere lol. here's what I got. I just copied your code as it was easier just easier to do so :P

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

        public void save(OutputStream outputStream) throws Exception {
            PrintStream out = new PrintStream(outputStream);
            if (users.size() > 0) {
                User temp = users.get(0);
                String firstName = temp.getFirstName();
                String lastName = temp.getLastName();
                String birthday = temp.getBirthDate().toString();
                String sex = temp.isMale() ? "true" : "false";
                String country = temp.getCountry().toString();
                out.print(firstName + "," + lastName + "," + birthday + "," + sex + "," + country);

                    for (int i = 1; i < users.size(); i++) {
                        temp = users.get(i);
                        firstName = temp.getFirstName();
                        lastName = temp.getLastName();
                        birthday = temp.getBirthDate().toString();
                        sex = temp.isMale() ? "true" : "false";
                        country = temp.getCountry().toString();
                        out.print("\n" + firstName + "," + lastName + "," + birthday + "," + sex + "," + country);
                    }
            }
            users.clear();
            out.close();
        }

Jason

Level 26 , Rancho Cucamonga, United States

26 November 2019, 19:46

public void load(InputStream inputStream) throws Exception {
           BufferedReader bR = new BufferedReader(new InputStreamReader(inputStream));
           String in;
           while ((in = bR.readLine()) != null){
               String[] inStrings = in.split(",");
               String firstName = inStrings[0];
               String lastName = inStrings[1];
               String birthday = inStrings[2];
               String sex = inStrings[3];
               String country = inStrings[4];

               User user = new User();

               //Name
               user.setFirstName(firstName);
               user.setLastName(lastName);

               //Birthday
               SimpleDateFormat formatter = new SimpleDateFormat("EEEE, dd/MM/yyyy/hh:mm:ss");
               Date parsedDate = formatter.parse(birthday);
               user.setBirthDate(parsedDate);

               //Sex
               if (sex.equals("true")) {
                   user.setMale(true);
               }
               else {
                   user.setMale(false);
               }

               //country
               user.setCountry(User.Country.valueOf(country));

               users.add(user);
           }
           bR.close();

Guadalupe Gagnon

Level 37 , Tampa, United States

26 November 2019, 20:10

solution

Running your code now I get an error on the load that is caused from the SimpleDateFormat. In the save method you are just passing the default string from the date. You can fix the load method by passing the default pattern of the Date object's toString(), which is: "EEE MMM dd HH:mm:ss zzz yyyy" or just remove all that and pass the string directly to a Date constructor (which has been deprecated) like this: user.setBirthDate(new Date(birthday));

Jason

Level 26 , Rancho Cucamonga, United States

26 November 2019, 22:31

I went with the your first recommendation and just used the pattern you gave me, I had looked mine up and I had thought that that was the default pattern but it turned out not to be true. Also, to get my code to work I had to take out the clear() on the users ArrayList which I am still a bit confused about but I guess it's just what ever :P. Once again thank you very much Gagnon, and you are invaluable member of this community. <3

Guadalupe Gagnon

Level 37 , Tampa, United States

26 November 2019, 23:09

I had to google that myself, I definitely don't know/remember everything about java. The .clear(), and I am theorizing here, was failing because when the verification tested the code it started with one Codegym object, added some users to the internal array, saved it with the method, created a new Codegym object, loaded the users from the file, then compared the two objects to make sure everything was done correctly. All of that in semi-code:

File file = new File(pathTofile);
CodeGym test = new CodeGym()
// code to create any number of users and add them to test.users
FileOutPutStream out = new FileOutPutStream(file);
test.save(out);
out.close();

Codegym copy = new CodeGym();
FileInputStream in = new FileInputStream(file);
copy.load(in);
in.close();

// now check that all the users from test are also in copy