This page will be full of code examples and external resources for when you're programming and forget how to do something
If statements
If statements should be used when your program needs to make decisions.
This is a basic if statement.int x = 0;
if (x > 100) {
print("X is big!");
} else {
print("X is small");
}
Check if the variable input is equal to the variable passcode.
int passcode = 651;
int input = 123;
if (input == passcode) {
print("You typed the correct password");
}
Draw a background if the mouse is on the left half of the screen.
if (mouseX < screenWidth / 2) {
background(255, 0, 0);
}
While loops
Use these when something needs to happen over and over.
This prints every number between 0 and 100.
int x = 0;
while (x < 100) {
print(x);
x += 1;
}
Draws circles accross the screen every 50 pixels.
int positionX = 0;
while (positionX < screenWidth) {
ellipse(positionX, 500, 20, 20)
positionX += 50;
}
Sets total equal to 100 letter a's
String total = "";
int number = 0;
while (number < 100) {
total += "a";
number += 1;
}
Functions
Functions are commands. There are many built into Processing, but you will
also need
to know how to create your own.
To call a function means to use the function.
void maybePrint(int x) {
if (x > 50) {
print("Yas");
}
}
This is how you can use that function.
maybePrint(60);
void drawCircle(int x, int y) {
ellipse(x, y, 50, 50);
}
Here's how you can call this function.
drawCircle(100, 50);
void printNumbersUpTo(int x) {
int y = 0;
while (x < x) {
print(y);
y += 1;
}
}
This is how you call this function.
printNumbersUpTo(75);
Arrays
Arrays are created in the following way :
int[] firstArray = new int[] { 99, 2, 5 };
int[] secondArray = new int[65];
Arrays can be used in the following way :
The following code will increase the first element by 2. Then next,
it will print the first element.
int[] ages = new int[] { 10, 12, 16 };
ages[0] += 2;
print(ages[0]);
Elements in an array are accessed by using their indexes :
int[] array = new int[50];
array[0] = 10;
array[1] = 50;
array[2] = 5;
array[0] = array[0] + array[1] + array[2];
print(array[0]);
We can create an array of anything, here's some examples :
String[] array = new String[10];
array[0] = "Moose";
array[1] = " is an awesome snake";
array[2] = array[0] + array[1];
print(array[2]);
Here's how you print everything in an array :
int[] numbers = new int[] { 999, 888, 777, 1, 2, 3 };
int i = 0;
while (i < numbers.length) {
print(numbers[i]);
i += 1;
}
Lists
This is how you create an ArrayList :
// Create a list of Strings
ArrayList<String> list = new ArrayList<String>();
// Create a list of integers
ArrayList<Integer> list = new ArrayList<Integer>();
// List of floats
ArrayList<Float> list = new ArrayList<Float>();
This is how you add to an ArrayList :
ArrayList<String> list = new ArrayList<String>();
list.add("Hi");
This is how you remove from an ArrayList :
ArrayList<String> list = new ArrayList<String>();
list.remove("Hi");
This is how get stuff from an ArrayList :
ArrayList<String> list = new ArrayList<String>();
list.get(0);
HashMap<String, Integer> map = new HashMap<String, Integer>();
map.put("Jon", 21);
map.put("Gary", 14);
map.put("Andrew", 19);
print(map.get("Jon"));
int x = 100, y = 100;
int speed = 3;
void setup() {
size(800, 600);
}
void draw() {
background(255, 255, 255);
fill(255, 0, 0);
updatePosition();
ellipse(x, y, 10, 10);
}
void updatePosition() {
if (keyPressed) {
if (key == 'w') {
y -= speed;
}
if (key == 's') {
y += speed;
}
if (key == 'a') {
x -= speed;
}
if (key == 'd') {
x += speed;
}
}
}
This is the rain program
int[] raindrops = new int[50];
float[] speed = new float[50];
void setup() {
size(500, 500);
int i = 0;
while (i < raindrops.length) {
speed[i] = 1;
raindrops[i] = (int) random(-height, 0);
i += 1;
}
}
void draw() {
background(255, 255, 255);
fill(0, 0, 255);
int i = 0;
while (i < raindrops.length) {
ellipse(width * ((1.0 * i) / raindrops.length), raindrops[i], 10, 10);
raindrops[i] += speed[i];
speed[i] *= 1.03;
if (raindrops[i] > 500) {
raindrops[i] = (int) random(-height, 0);
speed[i] = 1;
}
i += 1;
}
}