[Doc] - Improve javadocs and give credit for reused/referred code

Author: joel-lim

src/main/java/duke/Main.java

@@ -21,6 +21,7 @@ public class Main extends Application {
 
     @Override
     public void start(Stage stage) {
+        // Solution below adapted from JavaFx Tutorial by Jeffry Lum.
         FXMLLoader fxmlLoader = new FXMLLoader(Main.class.getResource("/view/Gui.fxml"));
         AnchorPane ap;
         try {
@@ -48,6 +49,5 @@ public void handle(WindowEvent event) {
         new Thread(() -> {
             duke.run();
         }).start();
-
     }
 }

src/main/java/duke/commands/Command.java

@@ -15,6 +15,7 @@ public interface Command {
      * @param arg   Arguments for the command (may be empty).
      * @param tasks List of Tasks.
      * @param ui    User interface for Duke.
+     * @param storage Storage for Duke.
      * @throws DukeException If inputs are invalid.
      */
     void execute(String arg, TaskList tasks, Ui ui, Storage storage) throws DukeException;

src/main/java/duke/ui/DialogBox.java

@@ -17,12 +17,13 @@
 
 import duke.exceptions.DukeException;
 
-
 /**
- * This control represents a dialog box consisting of an ImageView to represent the speaker's face and a label
- * containing text from the speaker.
+ * This control represents a dialog box consisting of an ImageView to represent
+ * the speaker's face and a label containing text from the speaker.
  */
 public class DialogBox extends HBox {
+    // @@author joel-lim-reused
+    // Reused from JavaFx Tutorial by Jeffry Lum.
     @FXML
     private Label dialog;
     @FXML
@@ -43,7 +44,8 @@ private DialogBox(String text, Image img) throws DukeException {
     }
 
     /**
-     * Flips the dialog box such that the ImageView is on the left and text on the right.
+     * Flips the dialog box such that the ImageView is on the left and text on the
+     * right.
      */
     private void flip() {
         ObservableList<Node> tmp = FXCollections.observableArrayList(this.getChildren());
@@ -52,13 +54,21 @@ private void flip() {
         setAlignment(Pos.TOP_LEFT);
     }
 
+    /**
+     * Gets a DialogBox with the User's image.
+     */
     public static DialogBox getUserDialog(String text, Image img) throws DukeException {
         return new DialogBox(text, img);
     }
 
+    /**
+     * Gets a flipped DialogBox with Duke's image.
+     */
     public static DialogBox getDukeDialog(String text, Image img) throws DukeException {
         var db = new DialogBox(text, img);
         db.flip();
         return db;
     }
+
+    // @@author
 }

src/main/java/duke/ui/Gui.java

@@ -18,6 +18,7 @@
  * Controller for the Main Window of the GUI for Duke.
  */
 public class Gui extends AnchorPane implements Ui {
+    // Solution below adapted from JavaFx Tutorial by Jeffry Lum.
     @FXML
     private ScrollPane scrollPane;
     @FXML