Add documentation for UserInterface and Parser class

src/main/java/budgetbuddy/parser/Parser.java

@@ -15,12 +15,23 @@
 import budgetbuddy.transaction.type.Transaction;
 import budgetbuddy.ui.UserInterface;
 
+/**
+ * Parses the user input into data that is easily understandable by other classes and methods.
+ */
 public class Parser {
 
     public static final int ADD_COMMAND_INDEX = 3;
     public static final int HELP_BEGIN_INDEX = 4;
     private static final int ADD_ACC_COMMAND_INDEX = 7;
 
+    /**
+     * The function `parseAccountNumber` extracts and returns an account number from a given input
+     * string following a specific syntax.
+     *
+     * @param input The input string that containes the account number to be parsed.
+     * @return The method is returning an integer value, which is the account number parsed from the
+     * input string.
+     */
     public static int parseAccountNumber(String input) throws InvalidArgumentSyntaxException {
         String data = input.substring(ADD_COMMAND_INDEX + 1);
         String[] parseData = data.split("/");
@@ -32,6 +43,16 @@ public static int parseAccountNumber(String input) throws InvalidArgumentSyntaxE
         throw new InvalidArgumentSyntaxException("Invalid add syntax.");
     }
 
+    /**
+     * The function `parseUserInputToTransaction` takes user input, parses it to create a transaction
+     * object (either income or expense), and handles various exceptions related to invalid input.
+     *
+     * @param input takes a user input that contain transaction details in a
+     * specific format.
+     * @param account The `account` parameter in this method represents the account to which the transaction belongs.
+     * @return The method `parseUserInputToTransaction` is returning a `Transaction` object, which can
+     * be either an `Income` or an `Expense` object based on the type provided in the input.
+     */
     public Transaction parseUserInputToTransaction(String input, Account account)
             throws InvalidTransactionTypeException, NumberFormatException,
             EmptyArgumentException, InvalidCategoryException, InvalidAddTransactionSyntax {
@@ -102,6 +123,18 @@ public Transaction parseUserInputToTransaction(String input, Account account)
     }
 
     //@@author Vavinan
+    /**
+     * The `parseEditTransaction` function in Java parses a new transaction string and creates either
+     * an Income or Expense object based on the transaction type, validating the category number and
+     * throwing exceptions for invalid data.
+     *
+     * @param newTransaction The `newTransaction` string is expected to be in a specific format
+     * @param account The `account` parameter in the `parseEditTransaction` method represents the
+     * account to which the transaction belongs.
+     * @return The `parseEditTransaction` method is returning a `Transaction` object, which can be
+     * either an `Income` or `Expense` object based on the type provided in the `newTransaction`
+     * string.
+     */
     public Transaction parseEditTransaction(String newTransaction, Account account) throws InvalidEditTransactionData,
             InvalidCategoryException {
         String[] parts = newTransaction.split(" \\| ");
@@ -135,6 +168,13 @@ public String parseHelpCommand(String input) {
     }
     //@@author
 
+    /**
+     * The `parseAddAccount` function in Java parses the input and returns the account name and
+     *  balance of the new account that is to added.
+     *
+     * @param input It contains details about account name and initial balance
+     * @return  A string array that contains the account name and initial balance
+     */
     public static String[] parseAddAccount(String input) throws NumberFormatException, EmptyArgumentException {
         String data = input.substring(ADD_ACC_COMMAND_INDEX + 1).trim();
         String[] parseData = data.split("/");
@@ -163,6 +203,12 @@ public static String[] parseAddAccount(String input) throws NumberFormatExceptio
         return new String[]{name, initialBalance};
     }
 
+    /**
+     * The `parseRemoveAccount` function in Java parses the input and returns the account
+     * number that is to be deleted
+     * @param input It contains details about account number that is to be deleted
+     * @return  A integer value representing the account number
+     */
     public static int parseRemoveAccount(String input)
             throws NumberFormatException, EmptyArgumentException {
         if (input.trim().length() < 11) {
@@ -175,7 +221,12 @@ public static int parseRemoveAccount(String input)
         return Integer.parseInt(data);
     }
 
-
+    /**
+     * The `parseEditAccount` function in Java parses the input and returns the account
+     * number that is to be edited
+     * @param input It contains details about account number  that is to be edited
+     * @return  A integer value representing the account number
+     */
     public static int parseEditAccount(String input) throws EmptyArgumentException {
         if (input.trim().length() < 9) {
             throw new EmptyArgumentException("edit-acc index ");