See reference: https://processing.org/reference/ArrayList.html
(But I think you got this already)
The main point in my opinion is not the Arraylist but what happens in the class you are using for its objects:
- In the class you store the positions of the cells and size and color and if it’s isAlive.
- Additionally you have the constructor and methods such as display() as described in the tutorial “objects”.
Example without a class
Here is an example without a class, just using the class PVector:
ArrayList<PVector> points = new ArrayList();
void setup() {
size(800, 800);
background(255);
} // function setup()
void draw() {
background(255);
// show points in green
strokeWeight(4);
stroke(0, 255, 0); // GREEN
for (PVector pv1 : points) {
point(pv1.x, pv1.y);
}
// read mouse
mousePressedThroughout();
}// function draw()
// -------------------------------------------------------------------
void keyPressed() {
// delete all
points.clear();
}
void mousePressedThroughout() {
// read mouse
if (mousePressed) {
//draw/add
points.add(new PVector(mouseX, mouseY));
}//if
}
//
More complex example with class
This is a more complex example with a class Spark (representing one spark within an explosion) and removing of old members of the ArrayList which are dead (in a for-loop backwards).
The ArrayList holds the sparks. Although the sparks belong to different firework explosions, they are all in ONE ArrayList.
ArrayList<Spark> sparks = new ArrayList();
int divider=1;
// ***************************************************************************
boolean videoExportIsOn1 = false;// *******************************************
// ***************************************************************************
// -------------------------------------------------------------------------------
void setup() {
size(1240, 960, P3D);
noStroke();
fill(255);
sphereDetail(5);
}
void draw() {
background(0);
lights();
// text
fill(255);
text("Click mouse to start firework. Hold any key for spheres.", 22, 22);
// manage sparks
if (keyPressed) {
noStroke();
}
for (Spark currentSpark : sparks) {
currentSpark.move();
currentSpark.display();
currentSpark.script();
}
// remove dead ones
for (int i=sparks.size()-1; i>=0; i--) {
Spark s = sparks.get(i);
if (s.isDead)
sparks.remove(i);
}
// spawn new
if (frameCount%divider == 0) {
mousePressedNew();
divider=int(random(13, 33));
}
// images for movie (menu tools)
if (videoExportIsOn1) {
// Saves each frame as line-000001.png, line-000002.png, etc.
saveFrame("line-######.png");
}
}
// ---------------------------------------------------------------------------------
// Input
void mousePressed() {
int colType=int(random (7));
for (int i=0; i<1000; i++) {
Spark spark = new Spark(width/2, height-4, 4);
sparks.add(spark);
spark.jump( mouseX, mouseY, colType);
}
}
// --------------------------------------------------------------------------
// Tools
void mousePressedNew() {
int colType=int(random (7));
float x= random(44, width-44);
float y= random(44, height-44); // random(33, 220);
for (int i=0; i<990; i++) {
Spark spark = new Spark(width/2, height-4, 4);
sparks.add(spark);
spark.jump( x, y, colType );
}
}
// ================================================================
class Spark {
float x, y, z; // position
float diameter; // Durchmesser
float gravity = 0.53; // Gravitation
color col;
final int stateWait=0;
final int stateTriggered=1;
final int stateJump=2;
int state = stateWait;
int timer;
int duration;
float angle, radius, radius_Add;
float maxRadius=1000;
float centerX, centerY;
boolean isDead=false;
// Constructor
Spark(float x_in, float y_in,
float diameter_in) {
x = x_in;
y = y_in;
diameter = diameter_in;
}// Constructor
void move() {
// Spark move
// move
x = centerX+cos(angle)*radius;
y = centerY+sin(angle)*radius;
radius+=radius_Add;
if (radius>maxRadius)
isDead=true;
}// function
// start spark
void jump( float x, float y, int colType ) {
timer=millis();
// duration for this spark to start after ignition
duration=int(random(0, 90));
state=stateTriggered;
centerX=x;
centerY=y;
angle=random(0, TWO_PI);
maxRadius= random(90, 200);
diameter=random(1.5, 7.7);
// print(colType);
switch (colType) {
case 0:
col = color(random(256), random(256), random(256));
break;
case 1:
col = color(random(256), 0, 0);
break;
case 2:
col = color(random(256));
break;
case 3:
col = color(random(254, 256));
break;
case 4:
// blue or white
if (random(100)>50)
col = color(0, 0, random(254, 256));//blue
else col = color(random(254, 256)); // white
break;
case 5:
// A or B
if (random(100)>50)
col = color(random(50, 256), random(50, 256), random(50, 256));
else col = color(random(256), random(256), random(256));
break;
default:
col = color(random(33), random(22), random(256));
break;
}
}
void script() {
switch(state) {
case stateWait:
//
diameter-=.1;
break;
case stateTriggered:
if (millis()-timer>duration)
state=stateJump;
break;
case stateJump:
jump2();
state=0;
break;
default:
println("Error 114");
exit();
break;
}//switch
}//method
void jump2() {
//starts explosion
radius_Add=random(2.1, 9.4);
}// function
void display() {
// Spark display
if (!keyPressed) {
fill(col);
ellipse(x, y, diameter, diameter);
} else {
pushMatrix();
translate(x, y, 0);
fill(col);
sphere(diameter);
popMatrix();
}//else
//
}// function
//
}//class
//
Warm regards,
Chrisir
