add additional questions by xuliny

src/Q5.java

@@ -82,4 +82,12 @@ public class Q5 extends AbstractGame {
         // (a)
         ball.update();
     }
+
+    // Additional exercise:
+    //      1. create a Player.java class just like you abstract the Ball
+    //      2. use up, down, left, right to control the player, stop player moving if it is going to be outside of the window
+    //      3. select some if condition block in update method and
+    //             - right click it -> refactor -> Extract -> Method
+    //         in order to improve the readability of your code :)
+    // SWEN20003 is fun!
 }