added comments to the purpose of each method and class

src/main/java/duke/Command.java

@@ -1,4 +1,5 @@
 package duke;
+//list of possible commands by the user
 public enum Command {
     TODO,
     DEADLINE,

src/main/java/duke/DateConverter.java

@@ -3,7 +3,9 @@
 import java.text.SimpleDateFormat;
 import java.util.Date;
 
+
 public class DateConverter {
+    // converts the input string from MMM dd yyyy to a Date object with "YYYY/MM/DD"
     public static String convertDate(String inputDateStr) {
         try {
             // Define a SimpleDateFormat for parsing the input date

src/main/java/duke/Deadline.java

@@ -5,22 +5,24 @@ public class Deadline extends Task {
     private LocalDate deadline;
 
 
-
+    // constructor of deadline takes in a string, whether it is marked and a deadline
     public Deadline(String name, boolean isMarked, LocalDate deadline) {
         super(name, isMarked);
         this.deadline = deadline;
     }
 
 
-
+    // gets the deadline of the Deadline object
     public LocalDate getDeadline() {
+
         return deadline;
     }
-
+    // sets the deadline of the Deadline Object
     public void setDeadline(LocalDate deadline) {
         this.deadline = deadline;
     }
 
+    // returns a String depending on if it is marked as [D] <marked/or not> <name of deadline task> by:<Date>
     @Override
     public String toString() {
         String status = isMarked ? "[X]" : "[ ]";

src/main/java/duke/Duke.java

@@ -30,130 +30,182 @@ public void run() {
             Command command = Parser.parseCommand(userInput);
             String description = Parser.parseDescription(userInput);
             switch (command) {
+                //if user wants to exit, tasks are saved and exit message is shown
                 case EXIT:
-                    storage.save(tasks, "tasks.txt");
-                    ui.closeScanner();
-                    ui.showExitMessage();
+                    handleExit();
                     return;
+                // lists all the tasks out
                 case LIST:
-                    ui.showTaskList(tasks);
+                    handleList();
                     break;
+                case FIND:
+                    handleFind(description);
+                    break;
+                // unmarks task
                 case UNMARK:
-                    try {
-                        int taskNumber = Integer.parseInt(description) - 1;
-                        if (taskNumber >= 0 && taskNumber < tasks.size()) {
-                            tasks.unmarkTask(taskNumber);
-                        } else {
-                            ui.showError("Task number out of range.");
-                        }
-                    } catch (NumberFormatException e) {
-                        ui.showError("Invalid task number. Please provide a valid integer.");
-                    }
+                    handleUnmark(description);
                     break;
+                //marks the task
                 case MARK:
-                    try {
-                        int taskNumber = Integer.parseInt(description) - 1;
-                        if (taskNumber >= 0 && taskNumber < tasks.size()) {
-                            tasks.markTaskAsDone(taskNumber);
-                        } else {
-                            ui.showError("Task number out of range.");
-                        }
-                    } catch (NumberFormatException e) {
-                        ui.showError("Invalid task number. Please provide a valid integer.");
-                    }
+                    handleMark(description);
                     break;
+                // if user wants to add a todo object
                 case TODO:
-                    try {
-                        if (description.isEmpty()) {
-                            throw new EmptyTodoException();
-                        }
-                        Todo todo = new Todo(description, false);
-                        tasks.addTask(todo);
-
-                    } catch (EmptyTodoException e) {
-                        System.out.println(e.getMessage());
-                    }
+                    handleTodo(description);
                     break;
+                // if user wants to input deadline
                 case DEADLINE:
-
-                    if (description.isEmpty()) {
-                        try {
-                            throw new EmptyDeadlineException();
-                        } catch (EmptyDeadlineException e) {
-                            System.out.println(e.getMessage());
-                        }
-                    } else {
-                        // Find the index of the deadline separator "/"
-                        int separatorIndex = description.indexOf('/');
-
-                        if (separatorIndex != -1) { // Ensure the separator exists in the input
-                            // Extract the task description and deadline
-
-                            String descriptionString = description.substring(0, separatorIndex).trim();
-                            String deadline = description.substring(separatorIndex + 4).trim();
-                            String pattern = "\\d{4}/\\d{2}/\\d{2}";
-                            Pattern datePattern = Pattern.compile(pattern);
-                            Matcher matcher = datePattern.matcher(deadline);
-                            if (matcher.find()) {
-                                DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy/MM/dd");
-                                LocalDate localDateDeadline = LocalDate.parse(deadline, formatter);
-                                Deadline deadlineTask = new Deadline(descriptionString, false, localDateDeadline);
-                                tasks.addTask(deadlineTask);
-
-                            } else {
-                                System.out.println("Please input your deadline in YYYY/MM/DD format");
-                            }
-                        } else {
-                            System.out.println("Invalid input format for deadline. Please input in the following format: <deadline> <description> /by <YYYY/MM/DD> ");
-                        }
-                    }
+                    handleDeadline(description);
                     break;
+                // if user wants to input an event
                 case EVENT:
-                    if (description.isEmpty()) {
-                        try {
-                            throw new EmptyEventException();
-                        } catch (EmptyEventException e) {
-                            System.out.println(e.getMessage());
-                        }
-                    } else {
-                        // Find the indices of the time separators
-                        int fromIndex = description.indexOf("/from");
-                        int toIndex = description.indexOf("/to");
-
-                        if (fromIndex != -1 && toIndex != -1) {
-                            // Extract the task description, startTime, and endTime
-                            String descriptionString = description.substring(0, fromIndex).trim();
-                            String startTime = description.substring(fromIndex + 5, toIndex).trim();
-                            String endTime = description.substring(toIndex + 3).trim();
-
-                            // Create a new Event object
-                            Event eventTask = new Event(descriptionString, false, startTime, endTime);
-                            tasks.addTask(eventTask);
-
-                        } else {
-                            System.out.println("Invalid input format for event command.");
-                        }
-                    }
+                    handleEvent(description);
                     break;
+                // if user wants to delete existing task
                 case DELETE:
-                    try {
-                        int taskNumber = Integer.parseInt(description) - 1;
-                        if (taskNumber >= 0 && taskNumber < tasks.size()) {
-                            tasks.deleteTask(taskNumber);
-                        } else {
-                            ui.showError("Task number out of range.");
-                        }
-                    } catch (NumberFormatException e) {
-                        ui.showError("Invalid task number. Please provide a valid integer.");
-                    }
+                    handleDelete(description);
                     break;
+                // if user just enters a completely invalid command
                 case INVALID:
-                    ui.showError("Invalid command. Please try again.");
+                    handleInvalid();
                     break;
             }
         }
     }
 
+    private void handleExit() {
+        storage.save(tasks, "tasks.txt");
+        ui.closeScanner();
+        ui.showExitMessage();
+    }
+
+    private void handleList() {
+        ui.showTaskList(tasks);
+    }
+
+    private void handleFind(String description) {
+        tasks.findTasksContainingKeyword(description);
+    }
+
+    private void handleUnmark(String description) {
+        // if user inputs task number, check if it is even an integer, and whether it is within range
+        try {
+            int taskNumber = Integer.parseInt(description) - 1;
+            if (taskNumber >= 0 && taskNumber < tasks.size()) {
+                tasks.unmarkTask(taskNumber);
+            } else {
+                ui.showError("Task number out of range.");
+            }
+
+        } catch (NumberFormatException e) {
+            ui.showError("Invalid task number. Please provide a valid integer.");
+        }
+    }
+
+    private void handleMark(String description) {
+        // if user inputs task number, check if it is even an integer, and whether it is within range
+        try {
+            int taskNumber = Integer.parseInt(description) - 1;
+            if (taskNumber >= 0 && taskNumber < tasks.size()) {
+                tasks.markTaskAsDone(taskNumber);
+            } else {
+                ui.showError("Task number out of range.");
+            }
+        } catch (NumberFormatException e) {
+            ui.showError("Invalid task number. Please provide a valid integer.");
+        }
+    }
+    private void handleTodo(String description) {
+        try {
+            if (description.isEmpty()) {
+                throw new EmptyTodoException();
+            }
+            Todo todo = new Todo(description, false);
+            tasks.addTask(todo);
+
+        } catch (EmptyTodoException e) {
+            System.out.println(e.getMessage());
+        }
+    }
+    private void handleDeadline(String description) {
+        if (description.isEmpty()) {
+            try {
+                throw new EmptyDeadlineException();
+            } catch (EmptyDeadlineException e) {
+                System.out.println(e.getMessage());
+            }
+        } else {
+            // Find the index of the deadline separator "/"
+            int separatorIndex = description.indexOf('/');
+
+            if (separatorIndex != -1) { // Ensure the separator exists in the input
+                // Extract the task description and deadline
+
+                String descriptionString = description.substring(0, separatorIndex).trim();
+                String deadline = description.substring(separatorIndex + 4).trim();
+                String pattern = "\\d{4}/\\d{2}/\\d{2}";
+                Pattern datePattern = Pattern.compile(pattern);
+                Matcher matcher = datePattern.matcher(deadline);
+                if (matcher.find()) {
+                    DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy/MM/dd");
+                    LocalDate localDateDeadline = LocalDate.parse(deadline, formatter);
+                    Deadline deadlineTask = new Deadline(descriptionString, false, localDateDeadline);
+                    tasks.addTask(deadlineTask);
+
+                } else {
+                    System.out.println("Please input your deadline in YYYY/MM/DD format");
+                }
+            } else {
+                System.out.println("Invalid input format for deadline. Please input in the following format: <deadline> <description> /by <YYYY/MM/DD> ");
+            }
+        }
+    }
+
+    private void handleEvent(String description) {
+        if (description.isEmpty()) {
+            try {
+                throw new EmptyEventException();
+            } catch (EmptyEventException e) {
+                System.out.println(e.getMessage());
+            }
+        } else {
+            // Find the indices of the time separators
+            int fromIndex = description.indexOf("/from");
+            int toIndex = description.indexOf("/to");
+
+            if (fromIndex != -1 && toIndex != -1) {
+                // Extract the task description, startTime, and endTime
+                String descriptionString = description.substring(0, fromIndex).trim();
+                String startTime = description.substring(fromIndex + 5, toIndex).trim();
+                String endTime = description.substring(toIndex + 3).trim();
+
+                // Create a new Event object
+                Event eventTask = new Event(descriptionString, false, startTime, endTime);
+                tasks.addTask(eventTask);
+
+            } else {
+                System.out.println("Invalid input format for event command.");
+            }
+        }
+    }
+
+    private void handleDelete(String description) {
+        try {
+            int taskNumber = Integer.parseInt(description) - 1;
+            if (taskNumber >= 0 && taskNumber < tasks.size()) {
+                tasks.deleteTask(taskNumber);
+            } else {
+                ui.showError("Task number out of range.");
+            }
+        } catch (NumberFormatException e) {
+            ui.showError("Invalid task number. Please provide a valid integer.");
+        }
+    }
+
+    private void handleInvalid() {
+        ui.showError("Invalid command. Please try again.");
+    }
+
     public static void main(String[] args) {
         new Duke("tasks.txt").run();
     }

src/main/java/duke/EmptyDeadlineException.java

@@ -1,4 +1,5 @@
 package duke;
+// if the description of a deadline is empty, return error message
 public class EmptyDeadlineException extends Exception {
     public EmptyDeadlineException() {
         super("OOPS!!! The description of a deadline cannot be empty.");

src/main/java/duke/EmptyEventException.java

@@ -1,4 +1,5 @@
 package duke;
+// if the description of an event is empty, return error message
 public class EmptyEventException extends Exception {
     public EmptyEventException() {
         super("OOPS!!! The description of an event cannot be empty.");

src/main/java/duke/EmptyTodoException.java

@@ -1,4 +1,5 @@
 package duke;
+// if the description of a todo is empty, return error message
 public class EmptyTodoException extends Exception {
     public EmptyTodoException() {
         super("OOPS!!! The description of a todo cannot be empty.");

src/main/java/duke/Event.java

@@ -1,26 +1,33 @@
 package duke;
+
 public class Event extends Task {
     private String startTime;
     private String endTime;
 
+    //Event objects inherit from tasks and has additional attributes start and end time
+
     public Event(String name, boolean isMarked, String startTime, String endTime) {
         super(name, isMarked);
         this.startTime = startTime;
         this.endTime = endTime;
     }
 
+    //getter of start time of event
     public String getStartTime() {
         return startTime;
     }
 
+    // setter of start time for event
     public void setStartTime(String startTime) {
         this.startTime = startTime;
     }
 
+    // getter of end time for event
     public String getEndTime() {
         return endTime;
     }
 
+    // setter of end time for event
     public void setEndTime(String endTime) {
         this.endTime = endTime;
     }

src/main/java/duke/Exit.java

@@ -1,4 +1,6 @@
 package duke;
+
+// when user enters bye and wants to exit the bot , this message is shown
 public class Exit {
     public String exitMessage() {
         return "Bye. Hope to see you again soon!";