・ Premises
A program is organized by processing. I am a beginner.
When I asked "I would like to add a fireworks-like diffusion to my program," I received the following program.
・ I want to realize
I want to keep drawing a circle without clicking on the execution result and let it spread wherever I click instead of clicking each circle. Also, if you click, I want to spread all the circles that are drawn.
1. Randomly colored circles continue to be drawn at random locations according to the music → 2. Click on the screen at any time to spread all the drawn circles → 3. Circles drawn when you click Only after spreading and clicking, the drawn circle remains → it becomes 1 again.

When the corresponding source code is executed, the execution result is drawn a circle once, and then the circle is clicked and diffused to draw the next circle.
I don't know why the next circle is not drawn unless I click it. In addition, the mouse click part uses various variables, and I do not know which one is linked and clicked, so I am worried about where to change it.

import ddf.minim. *;
import ddf.minim.analysis. *;
import ddf.minim.effects. *;
import ddf.minim.signals. *;
import ddf.minim.spi. *;
import ddf.minim.ugens. *;
Minim minim;
AudioPlayer player;
int buffersize = 512;
class Note {
  final float x;
  final float y;
  final float w;
  final float h;
  final float r;
  final float r2;
  final color col;// HSB, alpha
  boolean isAlive = true;
  Note (final float x, final float y, final float playerIn) {
    this.x = x;
    this.y = y;
    this.w = playerIn * 2;
    this.h = playerIn * 2;
    this.r = this.w/2;
    this.r2 = this.r * this.r;
    this.col = color (random (360), 100, 100, 50);
  }
  void draw () {
    noStroke ();
    fill (col);
    ellipse (x, y, w, h);
  }
  void update () {
  }
  boolean isExpired () {
    return! isAlive;
  }
  void toggle () {
    isAlive =! isAlive;
  }
}
abstract class Effect {
  protected float time;
  protected float t = 0;
  final float dt = 1.0;
  Effect () {
  }
  abstract void draw ();
  abstract void update ();
  void dec () {
    time-= dt;
    t + = dt;
  }
  boolean isExpired () {
    return time<0;
  }
}
abstract class MultiEffect extends Effect {
  ArrayList<Effect>chidren = new ArrayList<Effect>();
  MultiEffect () {
  }
  @Override
    void draw () {
    for (Effect eff: chidren) {
      eff.draw ();
    }
  }
  @Override
    void update () {
    for (Effect eff: chidren) {
      eff.update ();
    }
  }
  @Override
    boolean isExpired () {
    for (Effect eff: chidren) {
      if (! eff.isExpired ()) return false;
    }
    return true;
  }
}
class Bakuhatu extends Effect {
  final float x;
  final float y;
  float r;
  float dr = 1;
  final float ddr = 0.5;
  final int R, G, B;
  int alpha;
  int da = 0;
  final int dda = 1;
  Bakuhatu (final float x, final float y, final float r, final color col, final float time) {
    this.x = x;
    this.y = y;
    this.r = r;
    final int mask = 0xFF;
    alpha = (col >>24)&mask;
    alpha/= 2;
    R = (col >>16)&mask;
    G = (col >>8)&mask;B = col&mask;
    this.time = time;
  }
  @Override
    void draw () {
    noStroke ();
    colorMode (RGB);
    fill (R, G, B, alpha);
    ellipse (x, y, 2 * r, 2 * r);
  }
  @Override
    void update () {
    dec ();
    r + = dr;
    dr + = ddr;
    alpha-= da;
    da + = dda;
  }
}
final float g = 0.2;
class Hinoko extends Effect {
  float x;
  float y;
  final float r = 2;
  final float v0 = 5;
  float vx;
  float vy;
  final float theta;
  final color col;
  int R, G, B;
  int alpha;
  float da = 1;
  final float dda = 0.05;
  float drx, dry;
  float ddrx, ddry;
  Hinoko (final float x, final float y, final float r, final color col, final float theta, final float time) {
    this.x = x;
    this.y = y;
    this.vx = v0 * cos (theta);
    this.vy = v0 * sin (theta);
    this.col = col;
    final int mask = 0xFF;
    alpha = (col >>24)&mask;
    R = (col >>16)&mask;
    G = (col >>8)&mask;
    B = col&mask;
    this.drx = 0.5;
    this.dry = 0.05;
    this.ddrx = 0.5;
    this.ddry = 0.05;
    this.time = time;
    this.theta = theta;
  }
  @Override
    void draw () {
    noStroke ();
    colorMode (RGB);
    fill (R, G, B, alpha);
    ellipse (x, y, r, r);
  }
  @Override
    void update () {
    dec ();
    alpha-= da;
    da + = dda;
    x + = vx;
    y + = vy;
    y + = g * t;
    drx + = ddrx;
    dry + = ddry;
  }
}
class Hanabi extends MultiEffect {
  Hanabi (final float x, final float y, final float r, final color col) {
    super ();
    final float timeB = 30;
    chidren.add (new Bakuhatu (x, y, r, col, timeB));
    final float timeH = 50;
    final int max = 32;
    final float dtheta = TWO_PI/max;
    for (int i = 0;i<max;i ++) {
      chidren.add (new Hinoko (x, y, r, col, dtheta * i, timeH));
    }
  }
}
class Effects extends ArrayList<Effect>{
  Effects () {
    // do nothing
  }
  void add (Effects temp) {
    this.addAll (temp);
  }
  void draw () {
    for (Effect eff: this) {
      eff.draw ();
    }
  }
  void update () {
    ArrayList<Effect>temp = new ArrayList<Effect>();
    for (Effect eff: this) {
      eff.update ();
      if (! eff.isExpired ()) temp.add (eff);
    }
    this.clear ();
    this.addAll (temp);
  }
}
class NoteController {
  ArrayList<Note>notes = new ArrayList<Note>();
  ;
  final float margin = 100;final float xmin = margin;
  final float xmax = width-margin;
  final float ymin = margin;
  final float ymax = height-margin;
  NoteController () {
    //
  }
  void add (final float playerIn) {
    if (notes.size ()>10) return;// check
    if (playerIn<20) return;
    final float x = random (xmin, xmax);
    final float y = random (ymin, ymax);
    notes.add (new Note (x, y, playerIn));
  }
  void draw () {
    for (Note note: notes) {
      note.draw ();
    }
  }
  ArrayList<Note>update () {
    ArrayList<Note>next = new ArrayList<Note>();
    ArrayList<Note>del = new ArrayList<Note>();
    for (Note note: notes) {
      note.update ();
      if (note.isExpired ()) {
        del.add (note);
      } else {
        next.add (note);
      }
    }
    notes.clear ();
    notes.addAll (next);
    return del;
  }
  boolean isHit (final Note note) {
    if (mouseX<note.x-note.r) return false;
    if (mouseX>note.x + note.r) return false;
    if (mouseY<note.y-note.r) return false;
    if (mouseY>note.y + note.r) return false;
    return true;
  }
  int find () {
    int i = 0;
    for (Note note: notes) {
      if (isHit (note)) {
        return i;
      }
      i ++;
    }
    return -1;
  }
  void mouseClicked () {
    final int index = find ();
    if (index == -1) return;
    notes.get (index) .toggle ();
  }
}
class Converter {
  Effects makeHanabis (ArrayList<Note>notes) {
    Effects temp = new Effects ();
    for (Note note: notes) {
      temp.add (makeHanabi (note));
    }
    return temp;
  }
  Hanabi makeHanabi (Note note) {
    Hanabi temp = new Hanabi (note.x, note.y, note.r, note.col);
    return temp;
  }
}
NoteController controller;
Effects effects;
Converter converter;
void setup () {
  fullScreen ();
  frameRate (60);
  colorMode (HSB, 360, 100, 100, 100);
  controller = new NoteController ();
  effects = new Effects ();
  converter = new Converter ();
  minim = new Minim (this);
  / *
Free Fantasy BGM Music Material Page 0/Demon Soul
   https://maoudamashii.jokersounds.com/list/bgm10.html
   * /
  final String fn = "bgm_maoudamashii_fantasy10.mp3";
  // final int bpm = 110;
  player = minim.loadFile (fn);
  player.loop ();
}
void draw () {
  background (0);
  final float playerIn = player.mix.level () * 200;
  controller.add (playerIn);
  controller.draw ();
  ArrayList<Note>temp = controller.update ();
  effects.add (converter.makeHanabis (temp));
  effects.draw ();
  effects.update ();
}
void stop () {
  minim.stop ();
  super.stop ();
}
void mouseClicked () {
  controller.mouseClicked ();
}

I left the mouse click once and tried to extract only the part that spreads like fireworks, but I got an error that it was linked with the mouse click program or the variable was not used. Oops. So I tried to modify the mouse click part, but I could only decipher what I was doing using truth, and I didn't know where it was connected and how it was processed.

Use Processing 3.5.3