1. Unit 7 - Short-Circuit Evaluation - De Morgan’s Laws - The switch statement - Type-casting in Java - Using Math.random()

2. Short-Circuit Evaluation
if (condition1 && condition2) ...
If condition1 is false, then condition2 is not evaluated (the result is false anyway)
if (condition1 || condition2) ...
If condition1 is true, then condition2 is not evaluated (the result is true anyway)

3. De Morgan’s Laws ! (p && q) evaluates to ( !p || !q )
One could think of it as the “Distributive Property” for Logic
! (p && q) evaluates to ( !p || !q )
! (p || q) evaluates to ( !p && !q )

4. The switch Statement switch (expression) { case value1: ... break;
default: }
The switch Statement
switch case
default
break
Don’t forget breaks!
Reserved words
Only works with:
int
char
enum

5. The switch Statement (cont’d)
The same case can have two or more labels. For example:
switch (num) {
case 1:
case 2:
System.out.println(“Buckle my shoe");
break;
case 3:
case 4:
System.out.println(“Shut the door"); …

6. The Cast Operator
Java allows a programmer to “cast” a piece of data to a different type when needed.
Can be useful if working with int values and a decimal result is needed.
For example, one might want the decimal equivalent of a fraction even though the numerator and denominator are integers.
Example:
decAnswer = (double)myDenominator /
(double)myNumerator;

7. Math.Random() returns a double value 0 ≤ x < 1
Can then be scaled to fit the needs of your application.
For example, if you needed a random number from 1 to 12, you would do something like this:
randNum = (int) (12 * Math.Random() ) + 1;

8. The Craps Project
The purpose of this case study is both to practice with if-else and boolean expressions and to discuss design topics: OO design, team development, and software reusability.

9. The Craps Project (cont’d)
Your job
Your assignment is placed into the context of a larger team effort. All you need to know is the public interfaces for your classes Die and CrapsGame, that is, their constructors and public methods.

10. The Craps Project (cont’d)
Step 1:
Test your CrapsGame class separately using the class CrapsTest1 provided to you.
CrapsTest1
It would take a long time to test your class in the real Craps program, with random numbers of points coming up on the dice. You want a more controlled test, in which you can specify the outcome of a “dice roll,” and you need to run through all relevant sequences of “roll” outcomes.
CrapsGame

11. The Craps Project (cont’d)
Step 2:
Use your Die and CrapsGame classes in the CrapsStats application.
CrapsStats
Note how the CrapsGame class is used in the Craps program, and also in the CrapsStats program. This is a simple example of reusability.
CrapsGame
Die

12. The Craps Project (cont’d)
Step 3:
Finish the RollingDie class (the drawDots method). Integrate CrapsGame and RollingDie into the Craps program.
Step 3 is here to let you code a switch.