A-CodeQuality, refactored code to follow good coding practices.

data/tasks.txt

@@ -1,5 +1,2 @@
-[A][ ] hehe
-[D][ ]  (by: now)
-[A][ ] airubg
-[D][ ] ugbia (by: efuba woubjs)
-[A][ ] ff
+[D][ ] uabrgiub (by: 12 Dec 1212 00:00)
+[A][ ] iguiugbf

src/main/java/Command/DeleteCommand.java

@@ -42,7 +42,7 @@ public DeleteCommand(int taskIndex) {
     @Override
     public String execute(TaskList taskList, Ui ui, Storage storage) throws DukeException {
         try {
-            assert taskIndex > 0 && taskIndex < taskList.getTaskCount() : "Invalid task index/ out of range";
+            assert taskIndex >= 0 && taskIndex <= taskList.getTaskCount() : "Invalid task index/ out of range";
             Task removedTask = taskList.deleteTask(taskIndex);
             storage.saveTask(taskList.getTasks());
             return ui.showDeletedTask(removedTask, taskList.getTaskCount());

src/main/java/Parser/Parser.java

@@ -54,20 +54,9 @@ public static Task parseTask(String taskData) throws FileNotFoundException, Duke
                 taskToAdd = new ToDo(taskInfo);
                 break;
             case "D":
-                taskInfo = taskInfo.substring(0, taskInfo.indexOf("(") - 1);
-                String xtraInfo = taskData.substring(taskData.indexOf("(") + 1, taskData.indexOf(")"));
-                String[] deadLineInfo = xtraInfo.split(": ");
-                String by = deadLineInfo[1];
-                taskToAdd = new DeadLine(taskInfo, by);
-                break;
+                return createDeadLineTask(taskInfo);
             case "E":
-                taskInfo = taskInfo.substring(0, taskInfo.indexOf('(') - 1);
-                String addInfo = taskData.substring(taskData.indexOf('(') + 1, taskData.indexOf(')'));
-                String[] eventInfo = addInfo.split(": ");
-                String from = eventInfo[1].substring(0, eventInfo[1].length() - 2).trim();
-                String to = eventInfo[2].trim();
-                taskToAdd = new Event(taskInfo, from, to);
-                break;
+                return createEventTask(taskInfo);
             default:
                 throw new DukeException("File is corrupted!");
             }
@@ -83,6 +72,44 @@ public static Task parseTask(String taskData) throws FileNotFoundException, Duke
         return null;
     }
 
+    /**
+     * Creates a DeadLine task based on task information.
+     *
+     * @param taskInfo The task information string containing the task description and deadline.
+     * @return A DeadLine task instance based on the task information.
+     * @throws DukeException If there is an issue parsing the task information.
+     */
+    private static Task createDeadLineTask(String taskInfo) throws DukeException {
+        try {
+            String[] parts = taskInfo.split(" \\(by: ");
+            String description = parts[0];
+            String by = parts[1].substring(0, parts[1].length() - 1);
+            return new DeadLine(description, by);
+        } catch (Exception e) {
+            throw new DukeException("Error parsing Deadline task: " + taskInfo);
+        }
+    }
+
+    /**
+     * Creates an Event task based on task information.
+     *
+     * @param taskInfo The task information string containing the task description and event details.
+     * @return An Event task instance based on the task information.
+     * @throws DukeException If there is an issue parsing the task information.
+     */
+    private static Task createEventTask(String taskInfo) throws DukeException {
+        try {
+            String[] parts = taskInfo.split(" \\(from: ");
+            String description = parts[0];
+            String[] dateParts = parts[1].split(" to ");
+            String from = dateParts[0];
+            String to = dateParts[1].substring(0, dateParts[1].length() - 1);
+            return new Event(description, from, to);
+        } catch (Exception e) {
+            throw new DukeException("Error parsing Event task: " + taskInfo);
+        }
+    }
+
     /**
      * Parses a user input string and creates the corresponding `Command` object.
      *
@@ -100,27 +127,100 @@ public static Command parse(String input) throws DukeException {
         case "list":
             return new ListCommand();
         case "todo":
-            String todoDesc = input.substring(5).trim(); // Extract the description
+            return createToDoCommand(input);
+        case "add":
+            return createAddCommand(input);
+        case "deadline":
+            return createDeadLineCommand(input);
+        case "event":
+            return createEventCommand(input);
+        case "unmark":
+            return createUnmarkCommand(input);
+        case "mark":
+            return createMarkCommand(input);
+        case "echo":
+            return createEchoCommand(input);
+        case "delete":
+            return createDeleteCommand(input);
+        case "help":
+            return new HelpCommand();
+        case "find":
+            return createFindCommand(input);
+        default:
+            throw new DukeException("I'm sorry, but I don't understand that command.");
+        }
+    }
+
+    /**
+     * Creates a ToDoCommand based on user input.
+     *
+     * @param input The user input string containing the command and description.
+     * @return A ToDoCommand instance based on the user input.
+     * @throws DukeException If there is an issue parsing the input.
+     */
+    private static ToDoCommand createToDoCommand(String input) throws DukeException {
+        try {
+            String todoDesc = input.substring(5).trim();
             Task todoTask = new ToDo(todoDesc);
             return new ToDoCommand(todoTask);
-        case "add":
+        } catch (Exception e) {
+            throw new DukeException("Error parsing ToDo command: " + input);
+        }
+    }
+
+    /**
+     * Creates an AddCommand based on user input.
+     *
+     * @param input The user input string containing the command and description.
+     * @return An AddCommand instance based on the user input.
+     * @throws DukeException If there is an issue parsing the input.
+     */
+    private static AddCommand createAddCommand(String input) throws DukeException {
+        try {
+            String[] words = input.split(" ");
             if (words.length < 2) {
                 throw new DukeException("Please specify a task to add.");
             }
             String addDesc = input.substring(4).trim();
             Task addTask = new Add(addDesc);
             return new AddCommand(addTask);
-        case "deadline":
-            String deadlineDesc = input.substring(8).trim(); // Extract the description
+        } catch (Exception e) {
+            throw new DukeException("Error parsing Add command: " + input);
+        }
+    }
+
+    /**
+     * Creates a DeadLineCommand based on user input.
+     *
+     * @param input The user input string containing the command and description.
+     * @return A DeadLineCommand instance based on the user input.
+     * @throws DukeException If there is an issue parsing the input.
+     */
+    private static DeadLineCommand createDeadLineCommand(String input) throws DukeException {
+        try {
+            String deadlineDesc = input.substring(8).trim();
             if (!deadlineDesc.contains("/by")) {
                 throw new DukeException("The deadline command should include '/by'.");
             }
             String[] deadlineParts = deadlineDesc.split("/by");
             String description = deadlineParts[0].trim();
             String by = deadlineParts[1].trim();
             return new DeadLineCommand(description, by);
-        case "event":
-            String eventDesc = input.substring(5).trim(); // Extract the description
+        } catch (Exception e) {
+            throw new DukeException("Error parsing Deadline command: " + input);
+        }
+    }
+
+    /**
+     * Creates an EventCommand based on user input.
+     *
+     * @param input The user input string containing the command and event description.
+     * @return An EventCommand instance based on the user input.
+     * @throws DukeException If there is an issue parsing the input.
+     */
+    private static EventCommand createEventCommand(String input) throws DukeException {
+        try {
+            String eventDesc = input.substring(5).trim();
             if (!eventDesc.contains("/from") || !eventDesc.contains("/to")) {
                 throw new DukeException("The event command should include '/from' and '/to'.");
             }
@@ -130,40 +230,108 @@ public static Command parse(String input) throws DukeException {
             String from = dateParts[0].trim();
             String to = dateParts[1].trim();
             return new EventCommand(eventDescription, from, to);
-        case "unmark":
-            if (words.length < 2) {
-                throw new DukeException("Please specify a task number to unmark.");
-            }
-            int taskNumberToUnmark = Integer.parseInt(words[1]) - 1; // Assuming tasks are 1-based
-            return new UnmarkCommand(taskNumberToUnmark);
-        case "mark":
+        } catch (Exception e) {
+            throw new DukeException("Error parsing Event command: " + input);
+        }
+    }
+
+    /**
+     * Creates a MarkCommand based on user input.
+     *
+     * @param input The user input string containing the command and task number to mark as done.
+     * @return A MarkCommand instance based on the user input.
+     * @throws DukeException If there is an issue parsing the input.
+     */
+    private static MarkCommand createMarkCommand(String input) throws DukeException {
+        try {
+            String[] words = input.split(" ");
             if (words.length < 2) {
                 throw new DukeException("Please specify a task number to mark as done.");
             }
-            int taskNumberToMark = Integer.parseInt(words[1]) - 1; // Assuming tasks are 1-based
+            int taskNumberToMark = Integer.parseInt(words[1]) - 1;
             return new MarkCommand(taskNumberToMark);
-        case "echo":
+        } catch (Exception e) {
+            throw new DukeException("Error parsing Mark command: " + input);
+        }
+    }
+
+    /**
+     * Creates an UnmarkCommand based on user input.
+     *
+     * @param input The user input string containing the command and task number to unmark.
+     * @return An UnmarkCommand instance based on the user input.
+     * @throws DukeException If there is an issue parsing the input.
+     */
+    private static UnmarkCommand createUnmarkCommand(String input) throws DukeException {
+        try {
+            String[] words = input.split(" ");
+            if (words.length < 2) {
+                throw new DukeException("Please specify a task number to unmark.");
+            }
+            int taskNumberToUnmark = Integer.parseInt(words[1]) - 1;
+            return new UnmarkCommand(taskNumberToUnmark);
+        } catch (Exception e) {
+            throw new DukeException("Error parsing Unmark command: " + input);
+        }
+    }
+
+    /**
+     * Creates an EchoCommand based on user input.
+     *
+     * @param input The user input string containing the command and text for the echo.
+     * @return An EchoCommand instance based on the user input.
+     * @throws DukeException If there is an issue parsing the input.
+     */
+    private static EchoCommand createEchoCommand(String input) throws DukeException {
+        try {
+            String[] words = input.split(" ");
             if (words.length < 2) {
                 throw new DukeException("Please provide text for the echo command.");
             }
-            String echoText = input.substring(5).trim(); // Extract the text
+            String echoText = input.substring(5).trim();
             return new EchoCommand(echoText);
-        case "delete":
+        } catch (Exception e) {
+            throw new DukeException("Error parsing Echo command: " + input);
+        }
+    }
+
+    /**
+     * Creates a DeleteCommand based on user input.
+     *
+     * @param input The user input string containing the command and task index to delete.
+     * @return A DeleteCommand instance based on the user input.
+     * @throws DukeException If there is an issue parsing the input.
+     */
+    private static DeleteCommand createDeleteCommand(String input) throws DukeException {
+        try {
+            String[] words = input.split(" ");
             if (words.length < 2) {
                 throw new DukeException("Please provide me a task index to delete");
             }
             int taskNumToDel = Integer.parseInt(words[1]) - 1;
             return new DeleteCommand(taskNumToDel);
-        case "help":
-            return new HelpCommand();
-        case "find":
+        } catch (Exception e) {
+            throw new DukeException("Error parsing Delete command: " + input);
+        }
+    }
+
+    /**
+     * Creates a FindCommand based on user input.
+     *
+     * @param input The user input string containing the command and keyword for searching.
+     * @return A FindCommand instance based on the user input.
+     * @throws DukeException If there is an issue parsing the input.
+     */
+    private static FindCommand createFindCommand(String input) throws DukeException {
+        try {
+            String[] words = input.split(" ");
             if (words.length < 2) {
                 throw new DukeException("Please provide a keyword for the find command.");
             }
             String keyword = input.substring(5).trim();
             return new FindCommand(keyword);
-        default:
-            throw new DukeException("I'm sorry, but I don't understand that command.");
+        } catch (Exception e) {
+            throw new DukeException("Error parsing Find command: " + input);
         }
     }
 }

src/main/java/Ui/Ui.java

@@ -14,6 +14,19 @@
  */
 public class Ui {
 
+    private static final String HELP_DESK = "List of Commands: Add, Deadline, Event, Todo, Echo,"
+            + "Mark, Unmark, Delete, Find, Bye\n"
+            + "1. Add - Add a task to the list\n"
+            + "2. Deadline - Add a task with a deadline\n"
+            + "3. Event - Add an event task\n"
+            + "4. Todo - Add a todo task\n"
+            + "5. Echo - Echo a message\n"
+            + "6. Mark - Mark a task as done\n"
+            + "7. Unmark - Unmark a task as done\n"
+            + "8. Delete - Delete a task\n"
+            + "9. Find - Find tasks by keyword\n"
+            + "10. Bye - Exit the program";
+
     /**
      * Displays a welcome message to the user when the application starts.
      *
@@ -49,17 +62,7 @@ public String showError(DukeException e) {
      * @return A list of available commands.
      */
     public String showCommands() {
-        return "List of Commands: Add, Deadline, Event, Todo, Echo, Mark, Unmark, Delete, Find, Bye\n"
-                + "1. Add - Add a task to the list\n"
-                + "2. Deadline - Add a task with a deadline\n"
-                + "3. Event - Add an event task\n"
-                + "4. Todo - Add a todo task\n"
-                + "5. Echo - Echo a message\n"
-                + "6. Mark - Mark a task as done\n"
-                + "7. Unmark - Unmark a task as done\n"
-                + "8. Delete - Delete a task\n"
-                + "9. Find - Find tasks by keyword\n"
-                + "10. Bye - Exit the program";
+        return HELP_DESK;
     }
 
     /**