1. Chapter 9 Arrays

2. What is an Array
An array is a special variable, which can hold a collection of elements of the same type.
Examples:
A list of colors
A list of objects, such as rain drops or cars
A list of players in a game
A sequential list of numbers to link to/associate with other variables such as x, y, w, h, color, etc.

3. Characteristics of Arrays
Arrays start with 0.
Arrays have a fixed size.
Each element in an array has a unique position, in which the order is crucial.
Each index/position of an array is matched with an element. E.g. array of your siblings you might be #2.
The size can be:
-A number
-A variable of int type
-An expression that calculates an integer

4. Declaring and Initializing Arrays
Declaring: int [] myArray; String [] myWord = new String[6];
Declaring and initializing with values : float[] myNums = { 1.0, 3.2, 6, 9.5};

5. …from processing.org/tutorials/arrays, an easier way to remember array declarations
// Declare
int[] data;  
// Create
data = new int[5];
// Assign
data[0] = 19;
data[1] = 40;
data[2] = 75;
data[3] = 76;
data[4] = 90;
// Declare & create
int[] data = new int[5];
// Assign
data[0] = 19;  
data[1] = 40;
data[2] = 75;
data[3] = 76;
data[4] = 90;
// Declare, create, assign
int[] data = { 19, 40, 75, 76, 90 };

6. Examples of specifying size
color [] swatches = new color[4]; int [] storeLoc = new int [12 ]; int cities = 5; string [] mycities = new string [cities]; int [] family = new int [siblings+parents]

7. In summary, 3 ways to fill with value (initialize)
Hard code the values in each spot.
Type out a list in curly brackets separated by commas.
Iterate through the elements in an array.
See next slide…

8. Table: Three ways to initialize
Hard code the values in each spot
String [] stuff = new String [4];
stuff[0] = "Buick";
stuff[1] = "Nissan";
stuff[2] = "Toyota";
stuff[3] = "Ford";
Type out a list in curly brackets separated by commas.
String [] siblings = {"Ernest", "Mary", "Therman"};
The above two methods are inefficient for large arrays. The third option is most widely used. Also, there are more advanced ways such as filling with data from a text file.
Iterate through the elements in an array. This also allows you to access each index value.
for(int i = 0; i < stuff.length; i++ { }

9. Accessing elements in Arrays
Several ways… Iterating through each element is one of them. See examples 9-5, 9-6, and 9-7. Then do #7

10. Create a Bar Chart
Remember Let’s do again. Then remix your own way.

11. Time for Fun Programming again
#54
A bit of a remix with names and descriptions of computer company founders

12. Do It Yourself:
Create a String array with about 5 names of family members.
Iterate through each.
If time permits, use a for() to place a rectangle around each name.
println() or text() to see results
(See solution at moorec.people.cofc.edu/fam.txt)

13. I started my own homework…

14. Jitterbug
Just another example. Nothing spectacular, but you can gain more experience on synthesizing current and past knowledge.
Jitterbug[] bugs = new Jitterbug[10];
void setup() {
size(240, 120);
for( int i = 0; i< bugs.length; i++) {
float x = random(width);
float y = random(height);
int r = i*2; //i did a remix here
bugs[i] = new Jitterbug(x, y, r); }
void draw() {
for(int i = 0; i<bugs.length; i++){
bugs[i].display();
bugs[i].move();
Main program on left and class on right.

15. Create class without looking:
Since we ran out of time, ignore the steps on these two pages. Instead we will open example Then study and modify it.
Create class without looking:
The class is called Ball
The data is:
float x for horiz position
float y for vert position
float w for width of circle
The method functions as follows:
Fills with a color
No stroke
Draws an ellipse with x, y, w, w arguments

16. Continue Incrementally:
Now pretend you only want an array that displays 3 balls. No movement, no gravity.
Modify page 181 to only display 3 balls from an array.