Critically examined the code and refactored it to improve the code qu…

src/main/java/AddCommand.java

@@ -25,7 +25,7 @@ public AddCommand (Task task) {
      * @return
      */
     @Override
-    public String execute(TaskList taskList, Ui ui, Storage storage) throws IOException {
+    public String execute(TaskList taskList, Ui ui, Storage storage) throws DukeException {
 
         taskList.add(task);
 

src/main/java/Command.java

@@ -12,7 +12,7 @@ public abstract class Command {
      * @param storage
      * @throws IOException
      */
-    public abstract String execute (TaskList taskList, Ui ui, Storage storage) throws IOException;
+    public abstract String execute (TaskList taskList, Ui ui, Storage storage) throws DukeException;
 
     /**
      * Checks whether the command is to exit the program

src/main/java/DeleteCommand.java

@@ -24,7 +24,7 @@ public DeleteCommand (int index) {
      * @throws IOException
      */
     @Override
-    public String execute(TaskList taskList, Ui ui, Storage storage) throws IOException {
+    public String execute(TaskList taskList, Ui ui, Storage storage) throws DukeException {
 
         Task task = taskList.delete(index);
 

src/main/java/DoneCommand.java

@@ -24,7 +24,7 @@ public DoneCommand (int index) {
      * @throws IOException
      */
     @Override
-    public String execute(TaskList taskList, Ui ui, Storage storage) throws IOException {
+    public String execute(TaskList taskList, Ui ui, Storage storage) throws DukeException {
 
         Task task = taskList.done(this.index);
 

src/main/java/Duke.java

@@ -72,7 +72,7 @@ public String run (String fullCommand) {
             Command c = Parser.parse(fullCommand);
             this.isExit = c.isExit();
             return c.execute(tasks, ui, storage);
-        } catch (IOException | DukeException e) {
+        } catch (DukeException e) {
             return ui.showError(e.getMessage());
         }
 

src/main/java/DukeException.java

@@ -22,4 +22,8 @@ public static DukeException emptyDescription () {
     public static DukeException outOfBounds () {
         return new DukeException("☹ OOPS!!! The number you inputted is out of bounds \uD83D\uDE22");
     }
+
+    public static DukeException couldNotSave () {
+        return new DukeException("☹ OOPS!!! Your task could not be saved/updated/deleted \uD83D\uDE22");
+    }
 }

src/main/java/ExitCommand.java

@@ -13,7 +13,7 @@ public class ExitCommand extends Command {
      * @throws IOException
      */
     @Override
-    public String execute(TaskList taskList, Ui ui, Storage storage) throws IOException {
+    public String execute(TaskList taskList, Ui ui, Storage storage) throws DukeException {
         return ui.bye();
     }
 

src/main/java/FindCommand.java

@@ -10,7 +10,7 @@ public FindCommand(String text) {
 
 
     @Override
-    public String execute(TaskList taskList, Ui ui, Storage storage) throws IOException {
+    public String execute(TaskList taskList, Ui ui, Storage storage) throws DukeException {
 
         Task[] matchedTasks = taskList.find(text);
 

src/main/java/ListCommand.java

@@ -14,7 +14,7 @@ public class ListCommand extends Command {
      * @throws IOException
      */
     @Override
-    public String execute(TaskList taskList, Ui ui, Storage storage) throws IOException {
+    public String execute(TaskList taskList, Ui ui, Storage storage) throws DukeException {
 
         return ui.list(taskList.list);
     }

src/main/java/Storage.java

@@ -94,17 +94,26 @@ public ArrayList<Task> retrieve () throws FileNotFoundException {
     /**
      * Saves the Tasks in a file
      * @param list The list of tasks to save
-     * @throws IOException
+     * @throws DukeException
      */
-    public void save (ArrayList<Task> list) throws IOException {
+    public void save (ArrayList<Task> list) throws DukeException {
+
+        try {
+
+            String s = "";
+
+            for (Task t : list) {
+                s += t.saveFormat() + System.lineSeparator();
+            }
+
+            this.writeToFile(filePath, s);
+
+        } catch (IOException e) {
 
-        String s = "";
+            throw DukeException.couldNotSave();
 
-        for (Task t : list) {
-            s += t.saveFormat() + System.lineSeparator();
         }
 
-        this.writeToFile(filePath, s);
     }
 
 }

src/main/java/TaskList.java

@@ -31,7 +31,10 @@ public void add (Task task) {
      * @param index The Index of the Task
      * @return
      */
-    public Task done (int index) {
+    public Task done (int index) throws DukeException {
+
+        if (index < 0 || index > list.size()) throw DukeException.outOfBounds();
+
         Task task = list.get(index);
         task.markAsDone();
 
@@ -43,7 +46,9 @@ public Task done (int index) {
      * @param index The index of the task
      * @return The deleted task
      */
-    public Task delete (int index) {
+    public Task delete (int index) throws DukeException {
+
+        if (index < 0 || index > list.size()) throw DukeException.outOfBounds();
 
         Task task = list.remove(index);
         return task;