arrays and looping through arrays with for loops!

1. TEA M TEAL
LIZ RUTLEDGE
DAY 9 rutle173@newschool.edu
August 11, 2011 esrutledge@gmail.com

2. agenda.
Review: Learn:
whatever you want. ARRAYS!!! (double-woooooooot!)
likely candidates: namely:
custom functions controlling a bunch of things
for loops individually without having to
write an entirely separate code
if statements
sequence for each one
mouse/keyboard interaction
boolean “switches”
also: looping through arrays
with a for loop
DAY 9
Tuesday, 11 Aug 2011
CODE
bootcamp 2011

3. homework
brainstorming!
questions?
mind-blowing discoveries?
new-found life goals?
http://vimeo.com/21651041
DAY 9
Tuesday, 11 Aug 2011
CODE
bootcamp 2011

4. arrays!
storing lots of little things in one bigger list of things.
the concept:
being able to store lots of related variables in one place so that you
can easily modify or control all those objects simultaneously
portability: way easier to control a million little shapes if they’re
all accessbile through the same array
readability: by keeping all your variables of a certain kind in one
place it’s easier to tell what you’re dealing with throughout the
code (and easier to remember variable names!)
scalability: you can increase the number of elements controlled
by your arrays by changing a single number
DAY 9
Tuesday, 11 Aug 2011
CODE
bootcamp 2011

5. how arrays work.
a quick example.
// define list of grocery items
to pick up at store as separate
this:
variables
String grocery1 = “beer”;
String grocery2 = “milk”;
String grocery3 = “bread”;
String grocery4 = “eggs”;
String grocery5 = “chocolate”;
// define list of grocery
items to pick up at store
as items in an array
String[] = new String[5];
turns groceries[0] = “beer”;
groceries[1] = “milk”;
into groceries[2] = “bread”;
this: groceries[3]
groceries[4]
=
=
“eggs”;
“chocolate”;
DAY 9
Tuesday, 11 Aug 2011
CODE
bootcamp 2011

6. how arrays work.
a quick example.
except now we can refer to ALL of our groceries at once:
println(grocery1); this println(groceries);
println(grocery2);
println(grocery3); // prints to the
println(grocery4); console:
vs.
println(grocery5); [0] “beer”
[1] “milk”
// prints to the console: [2] “bread”
beer [3] “eggs”
milk [4] “chocolate”
bread
eggs this
chocolate
DAY 9
Tuesday, 11 Aug 2011
CODE
bootcamp 2011

7. arrays and for loops.
putting that handy index
to work.
the concept:
looping through all the elements of an array
in english please?
remember how for loops increment through numbers? and how
arrays are indexed by numbers? not a coincidence.
we can use those same incrementing loops to do things to every
element in an array with very little effort!
DAY 9
Tuesday, 11 Aug 2011
CODE
bootcamp 2011

8. arrays and for loops.
putting that handy index
to work.
example:
looping through all the elements of an array
for( int i = 0; i < 5; i++) {
print(groceries[i]); this
}
println(grocery1);
println(grocery2);
vs.
// prints to the console:
println(grocery3);
beer
println(grocery4);
milk
println(grocery5);
bread
eggs
the // prints to the console:
chocolate
beer
old milk
way bread
eggs
chocolate
DAY 9
Tuesday, 11 Aug 2011
CODE
bootcamp 2011

9. homework.
due Friday, August 12th.
more bouncing ball[z]!
Redo your bouncing ball(s) sketch using arrays to create 50 bouncing balls.
The balls should have different sizes, colors, and speeds. (it’s okay if some overlap
but no two balls should be exactly alike.)
extra credit:
make each ball change color (independently) when it hits a surface and
bounces
extra extra credit:
store how many times each ball has bounced off a surface in another array
(hint: if you print out that array, faster moving balls should have a higher number of bounces)
DAY 9
Tuesday, 11 Aug 2011
CODE
bootcamp 2011