Second requirement is not validating. Should I compare the object that is being loaded to the ones already existing in the list?

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Should I compare the object that is being loaded to the ones already existing in the list? If they are the same should I replace the object in the list?

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.util.Date; import java.util.ArrayList; 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", ".txt"); String fileLocation = "D:\\Programare\\Codegym\\File1.txt"; OutputStream outputStream = new FileOutputStream(fileLocation); InputStream inputStream = new FileInputStream(fileLocation); CodeGym codeGym = new CodeGym(); // Initialize users field for the codeGym object here User user1 = new User("Andrei", "Branza", new java.util.Date(System.currentTimeMillis()), true, User.Country.OTHER); codeGym.users.add(user1); codeGym.save(outputStream); outputStream.flush(); CodeGym loadedObject = new CodeGym(); loadedObject.load(inputStream); // Here check that the codeGym object is equal to the loadedObject object System.out.println(codeGym.equals(loadedObject)); 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 fw = new PrintWriter(outputStream); if (this.users.size() > 0) { for (User user : this.users) { String sex; StringBuilder sb = new StringBuilder(); sb.append(user.getFirstName()); sb.append("/"); sb.append(user.getLastName()); sb.append("/"); sb.append(user.getBirthDate().getTime()); sb.append("/"); sex = user.isMale() ? "male" : "female"; sb.append(sex); sb.append("/"); sb.append(user.getCountry()); fw.println(sb.toString()); } } fw.close(); } public void load(InputStream inputStream) throws Exception { // Implement this method BufferedReader br = new BufferedReader(new InputStreamReader(inputStream)); while (br.ready()){ User user = new User(); String[] userLine = br.readLine().split("/"); if (userLine.length < 5) { break; } user.setFirstName(userLine[0]); user.setLastName(userLine[1]); user.setBirthDate(new Date(Long.parseLong(userLine[2]))); user.setMale(Boolean.parseBoolean(userLine[3])); switch (userLine[4]){ case "UNITED_STATES": user.setCountry(User.Country.UNITED_STATES); break; case "UNITED_KINGDOM": user.setCountry(User.Country.UNITED_KINGDOM); break; default: user.setCountry(User.Country.OTHER); break; } this.users.add(user); } br.close(); } @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

24 February 2021, 20:43

solution

The problem is that this code writes "male" or "female" at line 64-65 of the code in the save() method, however in the load() method at line 86 the code tries to parse a boolean. This will throw an error when it tries to parse "male" or "female". A couple things to help with the code: #1 You can just get the correct country with just a String:

String x = "UNITED_KINGDOM"; // string of a country
user.setCountry(User.Country.valueOf(x)); // creates the correct enum value

This avoids having to use a switch statement. #2 A foreach loop will be skipped if there are no values in the collection it will iterate. Because of this you don't need to check if there are values before it such as line 54 does.

Andrei

Level 41

24 February 2021, 20:54

Yes, it worked with changing the values from male / female to true / false. Thanks! Regarding #1 : but if I set the string x to retrieve whatever value is in the respective element of the array, I still need an if statement : if (!(userLine[4].equals("UNITED_STATES")) || !(userLine[4].equals("UNITED_KINGDOM")) user.setCountry(User.Country.OTHER); No ? For #2: yes, great point!

Guadalupe Gagnon

Level 37 , Tampa, United States

24 February 2021, 21:07

#1 not necessarily, there are only 4 possible values of userLine[4]: the 3 that are in the enum and "null". If you pass null to that method then you will end up with an exception. Because the other 3 values are guaranteed to be safe, all you need to logically check for is "null":

if(userLine[4].equals("null")) user.setCountry(User.Country.OTHER);
else user.setCountry(User.Country.valueOf(userLine[4]));

Andrei

Level 41

24 February 2021, 21:14

Ah yes, you are right. I was considering input from user for example : "ARGENTINA" and that would go to the other category. Your example makes more sense , yes.