Added some documentation to the code.

fixed a slight bug in the encofing of user data where evry user had the same password of "pass".

src/main/java/me/zacharias/bank/Account.java

@@ -48,7 +48,14 @@ public class Account {
         this.interestRate = interestRate;
         transactions.add(new Transaction(0, "Account opened", id, id, TransactionType.OPEN));
     }
-
+    
+    /**
+     * Withdraws the given amount from the account.
+     * @param amount The amount to be withdrawn
+     * @param description The description of the transaction
+     * @param destination The destination of the transaction
+     * @return The transaction object
+     */
     public Transaction WithdrawTransaction(double amount, String description, UUID destination) {
         if(amount < 0) {
             throw new IllegalArgumentException("Amount cannot be negative");
@@ -62,6 +69,13 @@ public class Account {
         return transaction;
     }
     
+    /**
+     * Deposits the given amount into the account.
+     * @param amount The amount to be deposited
+     * @param description The description of the transaction
+     * @param originator The originator of the transaction
+     * @return The transaction object
+     */
     public Transaction DepositTransaction(double amount, String description, UUID originator) {
         if(amount < 0) {
             throw new IllegalArgumentException("Amount cannot be negative");
@@ -72,6 +86,14 @@ public class Account {
         return transaction;
     }
     
+    /**
+     * Transfers the given amount from the account to the given destination.
+     * @param amount The amount to be transferred
+     * @param description The description of the transaction
+     * @param originator The originator of the transaction
+     * @param destination The destination of the transaction
+     * @return The transaction object
+     */
     public Transaction TransferTransaction(double amount, String description, UUID originator, UUID destination) {
         if(amount < 0 && balance < Math.abs(amount)) {
             throw new IllegalArgumentException("Insufficient balance");
@@ -82,6 +104,11 @@ public class Account {
         return transaction;
     }
     
+    /**
+     * Handles the given transaction.
+     * @param transaction The transaction to be handled
+     * @return The transaction object
+     */
     public Transaction handleTransaction(Transaction transaction) {
         if(transaction.getType() == TransactionType.WITHDRAW) {
             if(transaction.getAmount() < 0) {
@@ -103,6 +130,9 @@ public class Account {
         return transaction;
     }
     
+    /**
+     * Loads the transactions from the TransactionQue.json file for this account.
+     */
     public void load()
     {
         ArrayList<Transaction> transactions = Utils.GetTransactions(id);
@@ -111,40 +141,79 @@ public class Account {
             handleTransaction(transaction);
         }
     }
-
+    
+    /**
+     * Gets the name of the account.
+     * @return The name of the account
+     */
     public String getName() {
         return name;
     }
-
+    
+    /**
+     * Gets the balance of the account.
+     * @return The balance of the account
+     */
     public double getBalance() {
         return balance;
     }
     
+    /**
+     * Gets the ID of the account.
+     * @return The ID of the account
+     */
     public UUID getId() {
         return id;
     }
-
+    
+    /**
+     * Gets the transactions of the account.
+     * @return The transactions of the account
+     */
     public ArrayList<Transaction> getTransactions() {
         return transactions;
     }
     
+    /**
+     * Gets the interest of the account.
+     * @return The interest of the account
+     */
     public double getInterest() {
         return balance * (1+interestRate);
     }
     
+    /**
+     * Gets the interest rate of the account.
+     * @return The interest rate of the account
+     */
     @Override
     public String toString() {
         return toString(false);
     }
     
+    /**
+     * Gets the account as a string.
+     * @param negativ Whether to show the balance as
+     * @return The account as a string
+     */
     public String toString(boolean negativ)
     {
         return name + " - " + (negativ ? -balance : balance) + " kr";
     }
     
+    /**
+     * Contains the interest rates of the accounts.
+     */
     public static class Interests
     {
+        /**
+         * Interest rate of the bank account.
+         */
         public static final double BANK_ACCOUNT_INTEREST_RATE = 0.001;
+        
+        /**
+         * Interest rate of the savings account.
+         */
         public static final double SAVINGS_ACCOUNT_INTEREST_RATE = 0.05;
     }
 }

src/main/java/me/zacharias/bank/AccountType.java

@@ -1,7 +1,19 @@
 package me.zacharias.bank;
 
+/**
+ * Represents the type of an account.
+ */
 public enum AccountType {
+    /**
+     * Bank account type.
+     */
     BANK_ACCOUNT,
+    /**
+     * Savings account type.
+     */
     SAVINGS_ACCOUNT,
+    /**
+     * Unknown account type.
+     */
     UNKNOWN,
 }

src/main/java/me/zacharias/bank/BankAccount.java

@@ -3,9 +3,13 @@ package me.zacharias.bank;
 import static me.zacharias.bank.Account.Interests.BANK_ACCOUNT_INTEREST_RATE;
 
 /**
- * This class only works as a way to have prefilled information, but can be replaced by just calling the {@link Account#Account(String, double, double)} instead
+ * This class only works as a way to have prefilled information, but can be replaced by just calling the {@link Account#Account(String, double)} instead
  */
 public class BankAccount extends Account {
+    /**
+     * Creates a new BankAccount with the given name.
+     * @param name The name of the account
+     */
     public BankAccount(String name) {
         super(name, BANK_ACCOUNT_INTEREST_RATE);
     }

src/main/java/me/zacharias/bank/Launcher.java

@@ -7,7 +7,16 @@ import java.io.InputStreamReader;
 import java.util.ArrayList;
 import java.util.UUID;
 
+/**
+ * Launcher class for the bank application.
+ * Used to provide an interface for creating new users.
+ */
 public class Launcher {
+    /**
+     * Main method for the launcher.
+     * Used to provide an interface for creating new users.
+     * @param args The command line arguments
+     */
     public static void main(String[] args) {
         ArrayList<String> argsList = new ArrayList<>();
         
@@ -50,7 +59,7 @@ public class Launcher {
                 
                 Account a = user.createAccount("Konto");
                 a.DepositTransaction(100, "Welcome to the bank", UUID.fromString("00000000-0000-0000-0000-000000000000"));
-                user.write();
+                user.write(password);
                 
                 users.add(user);
             }catch (Exception e) {

src/main/java/me/zacharias/bank/Main.java

@@ -9,6 +9,9 @@ import java.util.UUID;
 
 import static me.zacharias.bank.Utils.*;
 
+/**
+ * This is more or less just a test class.
+ */
 public class Main {
     User user;
 

src/main/java/me/zacharias/bank/SavingsAccount.java

@@ -3,10 +3,13 @@ package me.zacharias.bank;
 import static me.zacharias.bank.Account.Interests.SAVINGS_ACCOUNT_INTEREST_RATE;
 
 /**
- * This class only works as a way to have prefilled information, but can be replaced by just calling the {@link Account#Account(String, double, double)} instead
+ * This class only works as a way to have prefilled information, but can be replaced by just calling the {@link Account#Account(String, double)} instead
  */
 public class SavingsAccount extends Account{
-    
+    /**
+     * Creates a new SavingsAccount with the given name.
+     * @param name The name of the account
+     */
     public SavingsAccount(String name) {
         super(name, SAVINGS_ACCOUNT_INTEREST_RATE);
     }

src/main/java/me/zacharias/bank/User.java

@@ -10,29 +10,63 @@ import java.util.UUID;
 
 import static me.zacharias.bank.Utils.*;
 
+/**
+ * User class for the bank application.
+ * Used to store the user data.
+ */
 public class User {
+    /**
+     * The user's id.
+     */
     UUID id;
+    
+    /**
+     * The user's name.
+     */
     String name;
+    
+    /**
+     * The user's accounts.
+     */
     ArrayList<Account> accounts;
     
+    /**
+     * Creates a new User with the given name.
+     * @param name The name of the user
+     */
     public User(String name) {
         this.name = name;
         id = UUID.randomUUID();
         accounts = new ArrayList<>();
     }
     
+    /**
+     * Creates a new BankAccount with the given name.
+     * @param name The name of the account
+     * @return The created account
+     */
     public Account createAccount(String name) {
         Account account = new BankAccount(name);
         accounts.add(account);
         return account;
     }
     
+    /**
+     * Creates a new SavingsAccount with the given name.
+     * @param name The name of the account
+     * @return The created account
+     */
     public Account createSavingsAccount(String name) {
         Account account = new SavingsAccount(name);
         accounts.add(account);
         return account;
     }
-
+    
+    /**
+     * Gets the account with the given name.
+     * @param name The name of the account
+     * @return The account with the given name
+     */
     public Account getAccount(String name) {
         for (Account account : accounts) {
             if (account.name.equals(name)) {
@@ -41,7 +75,12 @@ public class User {
         }
         return null;
     }
-
+    
+    /**
+     * Gets the account with the given id.
+     * @param id The id of the account
+     * @return The account with the given id
+     */
     public Account getAccount(@NotNull UUID id) {
         for (Account account : accounts) {
             if (account.id.equals(id)) {
@@ -51,6 +90,10 @@ public class User {
         return null;
     }
     
+    /**
+     * Deletes the given account.
+     * @param account The account to be deleted
+     */
     public void deleteAccount(@NotNull Account account) {
         Account base = null;
         for(Account a : accounts) {
@@ -65,25 +108,40 @@ public class User {
         accounts.remove(account);
     }
     
+    /**
+     * Gets the user's name.
+     * @return The user's name
+     */
     public String getName() {
         return name;
     }
     
+    /**
+     * Gets the user's accounts.
+     * @return The user's accounts
+     */
     public ArrayList<Account> getAccounts() {
         return accounts;
     }
     
-    public void write() {
+    /**
+     * Writes the user data to the user file.
+     * @param password The password used to encrypt the user data
+     */
+    public void write(String password) {
         String user = SHA256(name);
         File userFile = new File("./users/" + user + ".json");
         String json = gson.toJson(this);
         try {
-            WriteFile(userFile, Encrypt(json, "pass"));
+            WriteFile(userFile, Encrypt(json, password));
         } catch (Exception e) {
             throw new RuntimeException(e);
         }
     }
     
+    /**
+     * Updates the accounts according to the TransactionQue.json file.
+     */
     public void update() {
         for(Account account : accounts) {
             account.load();

src/main/java/me/zacharias/bank/Utils.java

@@ -21,8 +21,14 @@ import java.util.ArrayList;
 import java.util.Base64;
 import java.util.UUID;
 
+/**
+ * Utils class for various utility functions.
+ */
 public class Utils {
     
+    /**
+     * Simple Gson instance for serialization and deserialization the User classes.
+     */
     public static final Gson gson;
     
     static {
@@ -38,6 +44,11 @@ public class Utils {
         }
     }
     
+    /**
+     * SHA256 hasing os string mostly used for having an abstract way of storing usernames
+     * @param input String to be hashed
+     * @return hashed string using the SHA256 algorithm
+     */
     public static String SHA256(String input) {
         MessageDigest sha256 = null;
         try {
@@ -61,8 +72,22 @@ public class Utils {
     private static final int ITERATIONS = 65536;
     private static final int SALT_LENGTH = 16;
     private static final int IV_LENGTH = 12;
-
+    
-    public static String Encrypt(String data, String username) throws NoSuchPaddingException, NoSuchAlgorithmException, InvalidAlgorithmParameterException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException, InvalidKeySpecException {
+    /**
+     * Encrypts the given data using AES/GCM/NoPadding with a random salt and IV.
+     * Used to encrypt the user data. before storing it in the user file.
+     * @param data The data in string format to be encrypted
+     * @param password The password used to derive the key for encryption
+     * @return The encrypted data
+     * @throws NoSuchPaddingException
+     * @throws NoSuchAlgorithmException
+     * @throws InvalidAlgorithmParameterException
+     * @throws InvalidKeyException
+     * @throws IllegalBlockSizeException
+     * @throws BadPaddingException
+     * @throws InvalidKeySpecException
+     */
+    public static String Encrypt(String data, String password) throws NoSuchPaddingException, NoSuchAlgorithmException, InvalidAlgorithmParameterException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException, InvalidKeySpecException {
         SecureRandom random = new SecureRandom();
 
         byte[] salt = new byte[SALT_LENGTH];
@@ -71,7 +96,7 @@ public class Utils {
         byte[] iv = new byte[IV_LENGTH];
         random.nextBytes(iv);
 
-        SecretKey key = deriveKey(username, salt);
+        SecretKey key = deriveKey(password, salt);
 
         Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
         GCMParameterSpec gcmSpec = new GCMParameterSpec(128, iv);
@@ -85,7 +110,21 @@ public class Utils {
 
         return Base64.getEncoder().encodeToString(combined);
     }
-
+    
+    /**
+     * Decrypts the given data using AES/GCM/NoPadding with a random salt and IV.
+     * Used to decrypt the user data. after retrieving it from the user file.
+     * @param data The data in string format to be decrypted
+     * @param username The password used to derive the key for decryption
+     * @return The decrypted data
+     * @throws NoSuchPaddingException
+     * @throws NoSuchAlgorithmException
+     * @throws InvalidAlgorithmParameterException
+     * @throws InvalidKeyException
+     * @throws IllegalBlockSizeException
+     * @throws BadPaddingException
+     * @throws InvalidKeySpecException
+     */
     public static String Decrypt(String data, String username) throws NoSuchPaddingException, NoSuchAlgorithmException, InvalidAlgorithmParameterException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException, InvalidKeySpecException {
         byte[] combined = Base64.getDecoder().decode(data);
 
@@ -107,13 +146,28 @@ public class Utils {
 
         return new String(decrptedData);
     }
-
+    
+    /**
+     * Derives the key from the given password and salt.
+     * Used to encrypt and decrypt the user data.
+     * @param password The password used to derive the key
+     * @param salt The salt used to derive the key
+     * @return The derived key
+     * @throws NoSuchAlgorithmException
+     * @throws InvalidKeySpecException
+     */
     private static SecretKey deriveKey(String password, byte[] salt) throws NoSuchAlgorithmException, InvalidKeySpecException {
         SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256");
         PBEKeySpec spec = new PBEKeySpec(password.toCharArray(), salt, ITERATIONS, KEY_SIZE);
         return new SecretKeySpec(factory.generateSecret(spec).getEncoded(), "AES");
     }
-
+    
+    /**
+     * Reads the given file and returns its content as a string.
+     * Used to read the user data from the user file.
+     * @param file The file to be read
+     * @return The content of the file as a string
+     */
     public static String ReadFile(File file)
     {
         if(!file.exists())
@@ -136,7 +190,13 @@ public class Utils {
             throw new RuntimeException(e);
         }
     }
-
+    
+    /**
+     * Writes the given data to the given file.
+     * Used to write the user data to the user file.
+     * @param file The file to write to
+     * @param data The data to be written
+     */
     public static void WriteFile(File file, String data) {
         if(file.exists())
         {
@@ -159,6 +219,11 @@ public class Utils {
         }
     }
     
+    /**
+     * Adds the given transaction to the transactionQue.json file.
+     * Used to add transactions to the transaction queue for later processing by the receiving account.
+     * @param transaction The transaction to be added
+     */
     public static void AddTrnsationQue(Transaction transaction) {
         try {
             File transactionQueFile = new File("./data/transactionQue.json");
@@ -192,6 +257,12 @@ public class Utils {
         }
     }
     
+    /**
+     * Gets all transactions from the transactionQue.json file.
+     * Used to get transactions from the transaction queue for later processing by the receiving account.
+     * @param account The account to get the transactions for
+     * @return The transactions from the transaction queue for the given account
+     */
     public static ArrayList<Transaction> GetTransactions(UUID account) {
         try{
             File transactionQueFile = new File("./data/transactionQue.json");
@@ -241,6 +312,13 @@ public class Utils {
         }
     }
     
+    /**
+     * Gets the JSONObject from the transactionQue.json file.
+     * Used to get the JSONObject from the transaction queue for later processing by the receiving account.
+     * @param transactionQueFile The file to get the JSONObject from
+     * @return The JSONObject from the transaction queue
+     * @throws IOException If an I/O error occurs
+     */
     private static @NotNull JSONObject getJsonObject(File transactionQueFile) throws IOException {
         if(!transactionQueFile.exists())
         {
@@ -274,6 +352,13 @@ public class Utils {
         return jsonObject;
     }
     
+    /**
+     * Validates the transactions in the TransactionQue.json file.
+     * Used to validate the transaction queue for later processing by the receiving account.
+     * @param transactions the transactions array from the TransactionQue.json file
+     * @param validation the provided hash value from the TransactionQue.json file
+     * @return weather or not the key is valid for the transactions array
+     */
     private static boolean validate(JSONArray transactions, String validation) {
         byte[] decodedBytes = Base64.getDecoder().decode(validation);
         StringBuilder result = new StringBuilder();

src/main/java/me/zacharias/bank/app/Main.java

@@ -47,7 +47,7 @@ public class Main extends JPanel {
     
     public void logout() {
         frame.remove(mainManu);
-        mainManu.user.write();
+        mainManu.user.write(new String(login.passwordField.getPassword()));
         mainManu = null;
         accountView = null;
         transactionView = null;

src/main/java/me/zacharias/bank/transaction/Transaction.java

@@ -6,13 +6,44 @@ import java.time.format.DateTimeFormatter;
 import java.util.UUID;
 
 public class Transaction {
+    /**
+     * Amount of the transaction.
+     */
     private double amount;
+    
+    /**
+     * Description of the transaction.
+     */
     private String description;
+    
+    /**
+     * Originator of the transaction.
+     */
     private UUID originator;
+    
+    /**
+     * Destination of the transaction.
+     */
     private UUID destination;
+    
+    /**
+     * Type of the transaction.
+     */
     private TransactionType type;
+    
+    /**
+     * Date of the transaction.
+     */
     private String date;
     
+    /**
+     * Creates a new transaction.
+     * @param amount Amount of the transaction.
+     * @param description Description
+     * @param destination Destination of the transaction.
+     * @param originator Originator of the transaction.
+     * @param type Type of the transaction.
+     */
     public Transaction(double amount, String description, UUID destination, UUID originator, TransactionType type) {
         this.amount = amount;
         this.description = description;
@@ -22,30 +53,59 @@ public class Transaction {
         date = LocalDateTime.now().format(DateTimeFormatter.ofPattern("dd.MM.yyyy HH:mm"));
     }
     
+    /**
+     * Gets the amount of the transaction.
+     * @return The amount of the transaction
+     */
     public double getAmount() {
         return amount;
     }
-
+    
+    /**
+     * Gets the description of the transaction.
+     * @return The description of the transaction
+     */
     public String getDescription() {
         return description;
     }
-
+    
+    /**
+     * Gets the originator of the transaction.
+     * @return The originator of the transaction
+     */
     public UUID getOriginator() {
         return originator;
     }
-
+    
+    /**
+     * Gets the destination of the transaction.
+     * @return The destination of the transaction
+     */
     public UUID getDestination() {
         return destination;
     }
-
+    
+    /**
+     * Gets the type of the transaction.
+     * @return The type of the transaction
+     */
     public TransactionType getType() {
         return type;
     }
     
+    /**
+     * Gets the date of the transaction.
+     * @return The date of the transaction
+     */
     public String getDate() {
         return date;
     }
     
+    /**
+     * Copies the transaction.
+     * @param transactionType Type of the transaction.
+     * @return A copy of the transaction.
+     */
     public Transaction copy(TransactionType transactionType) {
         return new Transaction(amount, description, destination, originator, transactionType);
     }

src/main/java/me/zacharias/bank/transaction/TransactionType.java

@@ -1,5 +1,28 @@
 package me.zacharias.bank.transaction;
 
 public enum TransactionType {
-    WITHDRAW, DEPOSIT, OPEN, TRANSFER, CLOSE
+    /**
+     * Transaction type for withdrawing money from the account.
+     */
+    WITHDRAW,
+    
+    /**
+     * Transaction type for depositing money into the account.
+     */
+    DEPOSIT,
+    
+    /**
+     * Transaction type for opening the account.
+     */
+    OPEN,
+    
+    /**
+     * Transaction type for transferring money from one account to another.
+     */
+    TRANSFER,
+    
+    /**
+     * Transaction type for closing the account.
+     */
+    CLOSE
 }