Apply refactoring to improve code quality

src/main/java/edith/Storage.java

@@ -56,7 +56,7 @@ public void save(ArrayList<Task> listOfTasks) throws IOException {
      * @throws IOException If an I/O error occurs while reading from the file.
      * @throws EdithException If the file contains corrupted data or the data format is invalid.
      */
-    public ArrayList<Task> load() throws IOException, EdithException {
+    public ArrayList<Task> load() throws IOException {
         ArrayList<Task> listOfTasks = new ArrayList<>();
         File file = new File(this.filePath);
         File directory = new File(file.getParent());
@@ -79,26 +79,7 @@ public ArrayList<Task> load() throws IOException, EdithException {
             String taskString = taskData[2].trim();
             Task task;
 
-            switch (typeOfTaskString) {
-            case "[T]":
-                task = new ToDo(taskString);
-                break;
-            case "[D]":
-                String[] deadlineParts = taskString.split(" /by ");
-                String deadlineTask = deadlineParts[0].trim();
-                String dueDate = deadlineParts[1].trim();
-                task = new Deadline(deadlineTask, dueDate);
-                break;
-            case "[E]":
-                String[] eventParts = taskString.split(" /from | /to ");
-                String eventTask = eventParts[0].trim();
-                String startTime = eventParts[1].trim();
-                String endTime = eventParts[2].trim();
-                task = new Event(eventTask, startTime, endTime);
-                break;
-            default:
-                throw new EdithException("An error occurred while parsing the Edith.task list. Data might be corrupted.", 1);
-            }
+            task = loadHelper(typeOfTaskString, taskString);
 
             if (statusString.equals("[X]")) {
                 task.markTaskDone();
@@ -108,4 +89,31 @@ public ArrayList<Task> load() throws IOException, EdithException {
         }
         return listOfTasks;
     }
+
+    public Task loadHelper(String typeOfTaskString, String taskString) throws EdithException {
+        Task task;
+
+        switch (typeOfTaskString) {
+        case "[T]":
+            task = new ToDo(taskString);
+            break;
+        case "[D]":
+            String[] deadlineParts = taskString.split(" /by ");
+            String deadlineTask = deadlineParts[0].trim();
+            String dueDate = deadlineParts[1].trim();
+            task = new Deadline(deadlineTask, dueDate);
+            break;
+        case "[E]":
+            String[] eventParts = taskString.split(" /from | /to ");
+            String eventTask = eventParts[0].trim();
+            String startTime = eventParts[1].trim();
+            String endTime = eventParts[2].trim();
+            task = new Event(eventTask, startTime, endTime);
+            break;
+        default:
+            throw new EdithException("An error occurred while parsing the Edith.task list. Data might be corrupted.", 1);
+        }
+
+        return task;
+    }
 }

src/main/java/edith/command/AddCommand.java

@@ -49,6 +49,27 @@ public AddCommand(String instruction) {
     @Override
     public String execute(TaskList tasks, Ui ui, Storage storage) throws EdithException {
         Task task = null;
+        task = addTaskHelper();
+
+        try {
+            tasks.addTask(task);
+            storage.save(tasks.getListOfTasks());
+
+            StringBuilder response = new StringBuilder();
+            response.append("Got it. I've added this task:\n")
+                    .append(task.toString()).append("\n")
+                    .append("There are now ").append(tasks.getNumOfTasks()).append(" tasks in your list.");
+
+            return response.toString();
+        } catch (DateTimeParseException e) {
+            throw new EdithException(ui.invalidDateTimeError(), 1);
+        } catch (IOException e) {
+            return "An error occurred while saving updated Edith.task list.";
+        }
+    }
+
+    public Task addTaskHelper() throws EdithException {
+        Task task;
 
         if (instruction.startsWith("todo ")) {
             String taskString = instruction.substring(5).trim();
@@ -77,20 +98,6 @@ public String execute(TaskList tasks, Ui ui, Storage storage) throws EdithExcept
             throw new EdithException("Invalid command for adding tasks.");
         }
 
-        try {
-            tasks.addTask(task);
-            storage.save(tasks.getListOfTasks());
-
-            StringBuilder response = new StringBuilder();
-            response.append("Got it. I've added this task:\n")
-                    .append(task.toString()).append("\n")
-                    .append("There are now ").append(tasks.getNumOfTasks()).append(" tasks in your list.");
-
-            return response.toString();
-        } catch (DateTimeParseException e) {
-            throw new EdithException(ui.invalidDateTimeError(), 1);
-        } catch (IOException e) {
-            return "An error occurred while saving updated Edith.task list.";
-        }
+        return task;
     }
 }

src/main/java/edith/command/DeleteCommand.java

@@ -44,7 +44,8 @@ public DeleteCommand(int index) {
     @Override
     public String execute(TaskList tasks, Ui ui, Storage storage) throws EdithException {
         if (index < 0 || index >= tasks.getNumOfTasks()) {
-            throw new EdithException("Task " + index + " does not exist. Please enter a valid task number.");
+            int num = index + 1;
+            throw new EdithException("Task " + num + " does not exist. Please enter a valid task number.");
         }
 
         Task taskToDelete = tasks.getTask(index);

src/main/java/edith/command/MarkCommand.java

@@ -44,7 +44,8 @@ public MarkCommand(int index) {
     @Override
     public String execute(TaskList tasks, Ui ui, Storage storage) throws EdithException {
         if (index < 0 || index >= tasks.getNumOfTasks()) {
-            throw new EdithException("Task " + index + " does not exist. Please enter a valid task number.");
+            int num = index + 1;
+            throw new EdithException("Task " + num + " does not exist. Please enter a valid task number.");
         }
 
         Task taskToMark = tasks.getTask(index);

src/main/java/edith/command/UnmarkCommand.java

@@ -44,7 +44,8 @@ public UnmarkCommand(int index) {
     @Override
     public String execute(TaskList tasks, Ui ui, Storage storage) throws EdithException {
         if (index < 0 || index >= tasks.getNumOfTasks()) {
-            throw new EdithException("Task " + index + " does not exist. Please enter a valid task number.");
+            int num = index + 1;
+            throw new EdithException("Task " + num + " does not exist. Please enter a valid task number.");
         }
 
         Task taskToUnmark = tasks.getTask(index);

src/main/java/edith/task/TaskList.java

@@ -108,15 +108,23 @@ public String listTasks(Ui ui) {
      * @param ui   The Ui object used to display the tasks.
      */
     public String listTasksOnDate(String date, Ui ui) {
-        int index = 1;
-        boolean isDue = false;
-        boolean isStartingOn = false;
-
         DateTimeFormatter formatter = DateTimeFormatter.ofPattern("d/M/yyyy");
         LocalDate localDate = LocalDate.parse(date, formatter);
 
+        int index = 1;
         StringBuilder response = new StringBuilder();
+
         response.append("Here are your tasks due by ").append(date).append(":\n");
+        listDueTasks(index, response, localDate);
+
+        response.append("Here are your events starting on ").append(date).append(":\n");
+        listEventsOnDate(index, response, localDate);
+
+        return response.toString();
+    }
+
+    public void listDueTasks(int index, StringBuilder response, LocalDate localDate) {
+        boolean isDue = false;
 
         for (Task task : listOfTasks) {
             if (task instanceof Deadline) {
@@ -141,8 +149,11 @@ public String listTasksOnDate(String date, Ui ui) {
         } else {
             response.append("\n");
         }
+    }
+
+    public void listEventsOnDate(int index, StringBuilder response, LocalDate localDate) {
+        boolean isStartingOn = false;
 
-        response.append("Here are your events starting on ").append(date).append(":\n");
         for (Task task : listOfTasks) {
             if (task instanceof Event) {
                 Event event = (Event) task;
@@ -157,8 +168,6 @@ public String listTasksOnDate(String date, Ui ui) {
         if (!isStartingOn) {
             response.append("NOTHING");
         }
-
-        return response.toString();
     }
 
     /**