Dear all,

 

For our next discussion on Monday, I’ll be doing something different. In the previous discussion classes, I always give you some discussion questions. However, in this class, I’ll give a short programming exercise to test your understanding about Class in Java. I’ll prepare one programming problem for you to try in the class. You can open anything: Java API, your lecture notes, and textbook.

 

Oh yes, you can find the answer for the previous discussion questions (discussion 3) in my website: www.comp.nus.edu.sg/~johannes#teaching

 

So, things that we are going to do in the class are as follows:

1.       Emphasize on some important concepts in the last lecture (testing & debugging). This will take approx. 20 mins

2.       Programming exercise. This will take approx. 40-50 mins

3.       Review of previous labs (Lab 1 and 2) and Lab 3. This will take approx. 30 mins

 

Regarding your labs, there’s a delay in releasing the result of your first lab because of some problems in CourseMarker marking site. I’ve also finished grading your second lab. If you have received the result of your lab (through e-mail), you’ll be able to see the comment from me in this form:

// johannes:

// -- my comment –

// ...

 

There are some common mistakes which need to be highlighted:

1.       Some of you forgot to write your name in the top part of your program. It’s important for you to write your own name in the space provided there, so I don’t need to go through the class list and check whose program is this.

2.       Writing comments (although the program is still simple) is important.

3.       Most of you forgot to remove Aaron’s name from your program. I supposed that Aaron has already told that you must remove his name from all of your programs, because it’s your program, not his.

4.       Actually this is not a mistake, but an advice from me: it’s a good programming practice not to import any packages which you do not use in your program, and not to declare variable which you do not use as well.

5.       In your Lab2Ex1: some of you didn’t use the computeArea() method inside Circle class to compute the area of the circle. Instead, some of you compute the area of the circle in the main method.

6.       In your Lab2Ex1: the erroneous method which you need to change is: void setRadius (double radius); Some of you failed to notice this. I’ll give a further explanation in the class

7.       In your Lab2Ex2: you should use the getX() and getY() method to get the coordinates for a certain point. Therefore, when printing out the coordinate, you should use df.format(p.getX()); for example.

8.       In your Lab2Ex2: some of you didn’t use the MyPoint class inside your main method at all.

 

Looking at your result, I’ll take some times to go through your second lab.

 

That’s all from me & happy weekend!