Recognize bodies involved in collision's class

Processing Libraries
1

Hi,

I am using Fisica library for a game. I have different types of FCircle (circle2, circle2) of different size and one type of FBox rectangle1. I am able to generate actions when a circle collides with a rectangle (make the circle disappear or fill black for example). I would like to be able to differentiate the bodies involved in the collision. Now, I can only refer to body1 and body2 which disregards the class. I would like to fill black circle1 and remove circle2 when they are the body involved in the collision with the rectangle. Here is my script with an attempt where I commented the lines that are not working.

Thank you for your help, I am very new to coding.

import fisica.*;
FWorld world;
FCircle circle1;
FCircle circle2;
FCircle circleButton1;
FCircle circleButton2;

FBox rectangle1;

int gx = 0; // horizontal gravity;
int gy= 0; // vertical gravity;

ArrayList<FBox> rectangles = new ArrayList<FBox>();
ArrayList<FCircle> circles1 = new ArrayList<FCircle>();
ArrayList<FCircle> circles2 = new ArrayList<FCircle>();

//------------------------------------------

void contactStarted(FContact c) {
 FBody circle1 = null;
 if (c.getBody1() == rectangle1){
   circle1 = c.getBody2();
 }
 else if ( c.getBody2() == rectangle1){
   circle1 = c.getBody1();
 }
 
 if (circle1 ==null){
   return;
 }
 
 world.remove(circle1);
}

  

//-----------------------------------
void setup() {
  size(1500, 2000); 
  smooth();
  
Fisica.init(this);

world = new FWorld ();
world.setEdges();

  circleButton1 = new FCircle(50);
  circleButton1.setPosition(1000/6, height-1900);
  circleButton1.setStatic(true);
  circleButton1.setGrabbable(false);
  circleButton1.setNoFill();
  circleButton1.setStroke(0);
  circleButton1.setGrabbable(false);
  circleButton1.setStrokeWeight(3);
  world.add(circleButton1);

  circleButton2 = new FCircle(50);
  circleButton2.setPosition(1000/5, height-1900);
  circleButton2.setStatic(true);
  circleButton2.setGrabbable(false);
  circleButton2.setNoFill();
  circleButton2.setStroke(0);
  circleButton2.setStrokeWeight(3);
  circleButton2.setGrabbable(false);
  world.add(circleButton2);

  rectangle1 = new FBox (225, 25);
  rectangle1.setPosition(200, 600);
  rectangle1.setVelocity(random(50, 250), random(50, 250));
  rectangle1.setRestitution(1);
  rectangle1.setDamping(0.0);
  rectangle1.setStatic(true);
  rectangle1.setGrabbable(false);
  rectangle1.setStrokeWeight(3);
  rectangle1.setFill(0);
  rectangle1.setStroke(0);
  rectangles.add(rectangle1);
  world.add(rectangle1);
}


void draw() {
  background(255);
  world.setGravity(gx, gy);

  if (keyPressed == true) {
    if (key == 'a') {
      gx = (-400); 
      gy = (100);
    }
    
    if (key == 'd') {
      gx = (400); 
      gy = (100);
    }

    if (key == 's') {
      gx = (0); 
      gy = (400);
    }

    if (key == 'w') {
      gx = (0); 
      gy = (-400);
    }
  } else {
    gx=0;
    gy=1000;
  }
  world.draw();
  world.step();
}

void mousePressed() {
  FBody pressed = world.getBody(mouseX, mouseY);
  if (pressed == circleButton1) {
    FCircle circle1 = new FCircle(30);
    circle1.setPosition(1000/6, height-1800);
    circle1.setRotation(random(TWO_PI));
    circle1.setVelocity(0, random(200, 500));
    circle1.setNoFill();
    circle1.setStroke(0);
    circle1.setGrabbable(false);
    circle1.setStrokeWeight(2);
    circles1.add(circle1);
    world.add(circle1);
  }
  
  if (pressed == circleButton2) {
    FCircle circle2 = new FCircle(80);
    circle2.setPosition(1000/6, height-1800);
    circle2.setRotation(random(TWO_PI));
    circle2.setVelocity(0, random(200, 500));
    circle2.setNoFill();
    circle2.setStroke(0);
    circle2.setStrokeWeight(2);
    circle2.setGrabbable(false);
    circles2.add(circle2);
    world.add(circle2);
  }
}