Fix checkstyle error

src/main/java/corgi/Corgi.java

@@ -26,7 +26,7 @@ public class Corgi {
     private Stack<Pair<State, Command>> history;
 
     /**
-     * Constructs new Corgi chatbot with an empty task list, 
+     * Constructs new Corgi chatbot with an empty task list,
      * a text renderer, a storage and a history stack.
      */
     public Corgi() {

src/main/java/corgi/State.java

@@ -17,7 +17,7 @@ public final class State {
 
     /**
      * Construct new state object with given task list, storage and text renderer.
-     * 
+     *
      * @param tasks The given task list.
      * @param storage The given storage.
      * @param renderer The given text renderer.
@@ -31,7 +31,7 @@ public State(
 
     /**
      * Getter for task list.
-     * 
+     *
      * @return The task list.
      */
     public TaskList getTaskList() {
@@ -40,7 +40,7 @@ public TaskList getTaskList() {
 
     /**
      * Getter for storage.
-     * 
+     *
      * @return The storage.
      */
     public Storage<Task> getStorage() {
@@ -49,7 +49,7 @@ public Storage<Task> getStorage() {
 
     /**
      * Getter for text renderer.
-     * 
+     *
      * @return The text renderer.
      */
     public TextRenderer getTextRenderer() {
@@ -58,7 +58,7 @@ public TextRenderer getTextRenderer() {
 
     /**
      * Add target task to the task list.
-     * 
+     *
      * @param task The target task.
      * @return New state with the updated task list.
      */
@@ -72,7 +72,7 @@ public State addTask(Task task) {
 
     /**
      * Remove task at the target index in the task list.
-     * 
+     *
      * @param index The target index.
      * @return New state with the updated task list.
      * @throws TaskListIndexOutOfBoundsException
@@ -87,14 +87,14 @@ public State removeTask(int index) throws TaskListIndexOutOfBoundsException {
 
     /**
      * Mark task at the target index to a given status.
-     * 
+     *
      * @param index The target index.
      * @param status The expected status.
      * @return New state with the updated task list.
      * @throws TaskListIndexOutOfBoundsException
      * @throws TaskStatusException
      */
-    public State markTask(int index, boolean status) 
+    public State markTask(int index, boolean status)
             throws TaskListIndexOutOfBoundsException, TaskStatusException {
         TaskList newTaskList = this.tasks.mark(index, status);
 

src/main/java/corgi/commands/Command.java

@@ -26,7 +26,7 @@ public Command(boolean isExit) {
 
     /**
      * Executes the command, performing its intended action on the provided task list,
-     * text renderer, and storage. Returns new state and string message 
+     * text renderer, and storage. Returns new state and string message
      *
      * @param currState The current state of the application.
      * @param history The history stack to store the states.

src/main/java/corgi/commands/FindTasksOnDateCommand.java

@@ -66,10 +66,10 @@ public Pair<State, String> execute(State currState, Stack<Pair<State, Command>>
 
         String outputDate = this.target.format(Task.DATE_OUTPUT_FORMATTER);
 
-         String returnMsg = tasksOnDate.isEmpty()
+        String returnMsg = tasksOnDate.isEmpty()
                 ? currTextRenderer.showNoTaskOnDate(outputDate)
                 : currTextRenderer.showTasksOnDate(outputDate, tasksOnDate.toString());
-        
+
         return new Pair<>(currState, returnMsg);
     }
 }

src/main/java/corgi/commands/MarkTaskCommand.java

@@ -60,7 +60,7 @@ public Pair<State, String> execute(State currState, Stack<Pair<State, Command>>
             String returnMsg = (status)
                     ? renderer.showTaskDone(list.getTaskInfo(this.index))
                     : renderer.showTaskUndone(list.getTaskInfo(this.index));
-            
+
             return new Pair<>(newState, returnMsg);
         } catch (TaskListIndexOutOfBoundsException e) {
             throw new CommandExecutionException("Invalid index provided!");

src/main/java/corgi/commands/UndoCommand.java

@@ -6,6 +6,9 @@
 import corgi.ui.TextRenderer;
 import javafx.util.Pair;
 
+/**
+ * Represents a command to undo previous command action.
+ */
 public class UndoCommand extends Command {
     /**
      * Initializes a new UndoCommand instance.
@@ -15,16 +18,16 @@ public UndoCommand() {
     }
 
     /**
-     * Executes the command by reverting the previous action based on the provided 
+     * Executes the command by reverting the previous action based on the provided
      * history stack and updating the task list accordingly.
      *
      * @param currState The current state of the application.
      * @param history The history stack to store the states.
      * @return A pair containing the new state and a string message indicating the result of the command execution.
      */
     @Override
-    public Pair<State, String> execute(State currState, Stack<Pair<State, Command>> history) 
-        throws CommandExecutionException {
+    public Pair<State, String> execute(State currState, Stack<Pair<State, Command>> history)
+            throws CommandExecutionException {
         if (history.isEmpty()) {
             throw new CommandExecutionException("Nothing to undo!");
         }

src/main/java/corgi/tasks/Deadline.java

@@ -34,15 +34,15 @@ public Deadline(boolean status, String desc, LocalDate by) {
     }
 
     @Override
-    public Deadline markAsDone() throws TaskStatusException{
+    public Deadline markAsDone() throws TaskStatusException {
         if (status) {
             throw new TaskStatusException("The task is already marked as done.");
         }
         return new Deadline(true, desc, by);
     }
 
     @Override
-    public Deadline markAsNotDone() throws TaskStatusException{
+    public Deadline markAsNotDone() throws TaskStatusException {
         if (!status) {
             throw new TaskStatusException("The task is already marked as not done.");
         }

src/main/java/corgi/tasks/Event.java

@@ -24,7 +24,7 @@ public Event(String desc, LocalDate from, LocalDate to) {
         this.to = to;
     }
 
-    
+
     /**
      * Initializes a new event task with the given status, description, start date, and end date.
      *
@@ -38,23 +38,23 @@ public Event(boolean status, String desc, LocalDate from, LocalDate to) {
         this.from = from;
         this.to = to;
     }
-    
+
     @Override
-    public Event markAsDone() throws TaskStatusException{
+    public Event markAsDone() throws TaskStatusException {
         if (status) {
             throw new TaskStatusException("The task is already marked as done.");
         }
         return new Event(true, desc, from, to);
     }
 
     @Override
-    public Event markAsNotDone() throws TaskStatusException{
+    public Event markAsNotDone() throws TaskStatusException {
         if (!status) {
             throw new TaskStatusException("The task is already marked as not done.");
         }
         return new Event(false, desc, from, to);
     }
-    
+
     /**
      * Checks if the event task is happening on the specified target date.
      *

src/main/java/corgi/tasks/TaskList.java

@@ -48,8 +48,8 @@ public TaskList add(Task t) {
      * without the removed task.
      *
      * @param index The index of the task to be removed.
-     * @throws TaskListIndexOutOfBoundsException If the index is invalid.
      * @return A new TaskList with the specified task removed.
+     * @throws TaskListIndexOutOfBoundsException If the index is invalid.
      */
     public TaskList remove(int index) throws TaskListIndexOutOfBoundsException {
         if (!isValidIndex(index)) {
@@ -65,9 +65,9 @@ public TaskList remove(int index) throws TaskListIndexOutOfBoundsException {
      *
      * @param index  The index of the task to be marked.
      * @param status The new status of the task.
+     * @return A new TaskList with the specified task's status updated.
      * @throws TaskListIndexOutOfBoundsException If the index is invalid.
      * @throws TaskStatusException If the task was already marked with the given status.
-     * @return A new TaskList with the specified task's status updated.
      */
     public TaskList mark(int index, boolean status) throws TaskListIndexOutOfBoundsException, TaskStatusException {
         if (!isValidIndex(index)) {

src/main/java/corgi/tasks/ToDo.java

@@ -25,15 +25,15 @@ public ToDo(boolean status, String desc) {
     }
 
     @Override
-    public ToDo markAsDone() throws TaskStatusException{
+    public ToDo markAsDone() throws TaskStatusException {
         if (status) {
             throw new TaskStatusException("The task is already marked as done.");
         }
         return new ToDo(true, desc);
     }
 
     @Override
-    public ToDo markAsNotDone() throws TaskStatusException{
+    public ToDo markAsNotDone() throws TaskStatusException {
         if (!status) {
             throw new TaskStatusException("The task is already marked as not done.");
         }