Computer Science 15-111 (Sections A & B), Spring 2007

Class Notes: 29-Jan-2007

Logistics

1. hw3 and hw2.ec due at 8pm tonight
2. Quiz 2: Wed, 31-Feb-2007 in class
3. Poll: quiz 2 review projected attendance
4. Quiz 1 Retake: Fri, 2-Feb-2007 in class
5. JCreator and DrJava
6. Reading:
1. Mon: Ch. 6.6 to 6.10 (and 6.0 - 6.5)
2. Wed: Ch 6.11 to 6.16
3. Fri: Ch 6.17 to 6.19
   
   

Topic Outline:

1. On Style: “Magic Numbers”

a. A simple rule: no literals in expressions besides -2, -1, 0, 1, 2.

b. Bad: drawCircle(pixels,250,50,50,…)

c. Better: drawCircle(pixels,width-radius,radius,radius,..)

d. Reads better, fewer bugs, more easily modified, etc, etc, etc…

2. Enumeration Operations (Section 6.4)

a. equals(), name(), ordinal(), values()

b. FadeType type1, type2;
if (type1.equals(type2)) { … } // not equals(type1,type2)

c. for (FadeType fadeType : FadeType.values()) {
System.out.printf("%d: %s\n”,fadeType.ordinal(),
fadeType.name());
}
Outputs:
0: HORIZONTAL_FADE
1: VERTICAL_FADE
2: RADIAL_FADE

3. Classes: a 10-minute tour of Sections 6.6 to 6.10

a. Create a new class (Counter)

b. Adding instance variables (value)

c. Adding instance methods (get(), click(), reset())

d. Making instance variables private

e. Counting instances

i. Adding a constructor (and losing the default constructor!)

ii. Adding a static (class) variable -- howMany

iii. Adding a static (class) method -- howMany()

4. Pixel image demo part 2: Zooms and/or Thumbnails of jpegs!

5. 2d Arrays: Either matrix operations or Gaussian Elimination (depending on time)