Lecture 6, CS 302-7 and 8, February 3

1. Reminders
1. OO change – Thursday now 1:30-2:30
2. First codelab assignment posted – announcements on course website
2. Review
1. Constants
2. Comments
3. I/O
4. Arithmetic
3. Arithmetic
1. Expression

i. Operand

ii. Operator

2. Modulo
3. Integer division

i. 3/2=1

ii. 3.0/2=1.5

4. Powers, roots – Math.pow, Math.sqrt

i. Math.pow(a,b); //a^b

ii. Math.sqrt(a); //sqrt(a)

iii. Squared - Might be easier just to do x * x

iv. Can use Math.pow to do cube root, cube, etc

5. Order of operations

i. Like standard math

ii. ()

iii. Will discuss more once we introduce a few more operators

6. Example –Quad.java
3. Random Class
1. What are random numbers?

i. pseudorandom vs random

1. True randomness: hotbits - http://www.fourmilab.ch/hotbits/

2. Use Random like Scanner
3. Step 1 : import java.util.Random();
4. Step 2: Random <name> = new Random();

i. Seed - > new Random(a);

5. Step 3: methods
6. .nextInt(a);

i. Returns an int between 0 and a (exclusive)

1. So, .nextInt(4) can return 0,1,2, or 3

7. .nextInt();

i. returns any int in range (-2,147,483,648 to 2,147,483,648)

8. .nextDouble();

i. returns a double between 0.0 and 1.0

9. Example – Dice.java
4. Strings
1. Strings are sequences of characters. Examples:

i. “ab”

ii. “c”

iii. “1”

iv. “&”

2. String name=”Rob”

i. Name is variable, “Rob” is literal

3. String length

i. name.length()

4. Empty String – “”

i. String empty=””;

ii. empty.length(); // 0

5. Concatenating strings

i. Like addition, for Strings

ii. String x=”x”;

iii. String y=”y”;

iv. String z=x+y;

v. S.o.p(z); //xy

1. (S.o.p is shorthand for System.out.println() – you still have to write it out in your programs)

6. HW
1. Read 3.1-3.2