Hi everyone,
I'm new in sketching with Processing and very very bad in English.
So, here's my sketch: I have a mobile square generating some points bouncing everywhere.
The problem is that bouncing is incorrect, I hope someone can find why of this.

Here's the code:

Mover mover;
// INIZIAZIONE VARIABILI
int width = 600;           // schermo
int height = 600;
float dim = 20;            // punti
float posX = width/2;      // quadratino
float posY = height/2;
int boxSize = 15;
boolean overBox = false;
boolean locked = false;
float xOffset = 0.0;
float yOffset = 0.0;
float pos2x = 20;          // secondo quadratino
float pos2y = 20;
int box2size = 15;
boolean overBox2 = false;
boolean locked2 = false;
float xOffset2 = 0.0;
float yOffset2 = 0.0;

void setup() {
  size (width, height);
  smooth();
  rectMode (RADIUS);
  mover = new Mover();
}

void draw() {
  background (255);
  // PUNTAMENTO PRIMO QUADRATO
  if (mouseX > posX - boxSize && mouseX < posX + boxSize &&
      mouseY > posY - boxSize && mouseY < posY + boxSize) {
        overBox = true;
        if (!locked) {
          stroke(255, 0, 0);
          strokeWeight(3);
        }
      } else {
        stroke (0);
        strokeWeight(2);
        overBox = false;
      }
      strokeWeight(2);
      rect (posX, posY, boxSize, boxSize);
  // PUNTAMENTO SECONDO QUADRATO
  if (mouseX > pos2x - box2size && mouseX < pos2x + box2size &&
      mouseY > pos2y - box2size && mouseY < pos2y + box2size) {
        overBox2 = true;
        if (!locked2) {
          stroke(0);
        }
      } else {
        overBox2 = false;
      }
      stroke (0);
      strokeWeight (2);
      rect (pos2x, pos2y, box2size, box2size);
  mover.update();
  mover.checkEdges();
  mover.display();
 
}

void mousePressed() {
  if (overBox) {            // pressione primo quadrato
    locked = true;
    xOffset = mouseX - posX;
    yOffset = mouseY - posY;
  } else {
    locked = false;
  }
 
  if (overBox2) {           // pressione secondo quadrato
    locked2 = true;
    xOffset2 = mouseX - pos2x;
    yOffset2 = mouseY - pos2y;
  } else {
    locked2 = false;
  }
}

void mouseDragged() {
  if (locked) {
    posX = mouseX - xOffset;
    posX = constrain (posX, 16, width - 17);
    posY = mouseY - yOffset;
    posY = constrain (posY, 16, height - 17);
  }
  if (locked2) {
    pos2x = mouseX - xOffset2;
    pos2x = constrain (pos2x, 31, width - 32);
    pos2y = mouseY - yOffset;
    pos2y = constrain (pos2y, 31, height - 32);
  }
}

void mouseReleased() {
  locked = false;
  locked2 = false;
}

class Mover {
 
  PVector location1;         // dichiarazione dei vettori
  PVector location2;
  PVector location3;
  PVector location4;
  PVector location5;
  PVector location6;
  PVector location7;
  PVector location8;
  PVector velocity1;
  PVector velocity2;
  PVector velocity3;
  PVector velocity4;
  PVector velocity5;
  PVector velocity6;
  PVector velocity7;
  PVector velocity8;
 
  Mover() {
    location1 = new PVector (posX, posY);   // dichiarazione del valore dei vettori
    location2 = new PVector (posX, posY);
    location3 = new PVector (posX, posY);
    location4 = new PVector (posX, posY);
    location5 = new PVector (posX, posY);
    location6 = new PVector (posX, posY);
    location7 = new PVector (posX, posY);
    location8 = new PVector (posX, posY);
    velocity1 = new PVector (0.5, 0);
    velocity2 = new PVector (0.35, 0.35);
    velocity3 = new PVector (0, 0.5);
    velocity4 = new PVector (-0.35, 0.35);
    velocity5 = new PVector (-0.5, 0);
    velocity6 = new PVector (-0.35, -0.35);
    velocity7 = new PVector (0, -0.5);
    velocity8 = new PVector (0.35, -0.35);
  }
 
  void update() {
    location1.add(velocity1);          // somma posizioni e velocità corrispondenti
    location2.add(velocity2);
    location3.add(velocity3);
    location4.add(velocity4);
    location5.add(velocity5);
    location6.add(velocity6);
    location7.add(velocity7);
    location8.add(velocity8);
  }

  void display() {
    stroke (0);
    strokeWeight(dim);
    point(location1.x,location1.y);
    point(location2.x,location2.y);
    point(location3.x,location3.y);
    point(location4.x,location4.y);
    point(location5.x,location5.y);
    point(location6.x,location6.y);
    point(location7.x,location7.y);
    point(location8.x,location8.y);
   
  }

  void checkEdges() { 
    frameRate(150);
    // CONTROLLO RIMBALZI PERIMETRO
    if ((location1.x >= width) || (location1.x <= 0)) {                          // controllo rimbalzo
    velocity1.x = velocity1.x * -1;
    }
    if ((location1.y >= height) || (location1.y <= 0)) {
    velocity1.y = velocity1.y * -1;
    }
    if ((location2.x >= width) || (location2.x <= 0)) {
    velocity2.x = velocity2.x * -1;
    }
    if ((location2.y >= height) || (location2.y <= 0)) {
    velocity2.y = velocity2.y * -1;
    }
    if ((location3.x >= width) || (location3.x <= 0)) {
    velocity3.x = velocity3.x * -1;
    }
    if ((location3.y >= height) || (location3.y <= 0)) {
    velocity3.y = velocity3.y * -1;
    }
    if ((location4.x >= width) || (location4.x <= 0)) {
    velocity4.x = velocity4.x * -1;
    }
    if ((location4.y >= height) || (location4.y <= 0)) {
    velocity4.y = velocity4.y * -1;
    }
    if ((location5.x >= width) || (location5.x <= 0)) {
    velocity5.x = velocity5.x * -1;
    }
    if ((location5.y >= height) || (location5.y <= 0)) {
    velocity5.y = velocity5.y * -1;
    }
    if ((location6.x >= width) || (location6.x <= 0)) {
    velocity6.x = velocity6.x * -1;
    }
    if ((location6.y >= height) || (location6.y <= 0)) {
    velocity6.y = velocity6.y * -1;
    }
    if ((location7.x >= width) || (location7.x <= 0)) {
    velocity7.x = velocity7.x * -1;
    }
    if ((location7.y >= height) || (location7.y <= 0)) {
    velocity7.y = velocity7.y * -1;
    }
    if ((location8.x >= width) || (location8.x <= 0)) {
    velocity8.x = velocity8.x * -1;
    }
    if ((location8.y >= height) || (location8.y <= 0)) {
    velocity8.y = velocity8.y * -1;
    }

    // CONTROLLO RIMBALZI QUADRATINO
    if ((location1.x > pos2x - box2size) && (location1.x < pos2x + box2size)) {      // 1°
        velocity1.x = velocity1.x * -1;
    }
    if ((location1.y > pos2y - box2size) && (location1.y < pos2y + box2size)) {
        velocity1.y = velocity1.y * -1;
    }
    if ((location2.x > pos2x - box2size) && (location2.x < pos2x + box2size)) {      // 2°
        velocity2.x = velocity2.x * -1;
    }
    if ((location2.y > pos2y - box2size) && (location2.y < pos2y + box2size)) {
        velocity2.y = velocity2.y * -1;
    }
    if ((location3.x > pos2x - box2size) && (location3.x < pos2x + box2size)) {      // 3°
        velocity3.x = velocity3.x * -1;
    }
    if ((location3.y > pos2y - box2size) && (location3.y < pos2y + box2size)) {
        velocity3.y = velocity3.y * -1;
    }
    if ((location4.x > pos2x - box2size) && (location4.x < pos2x + box2size)) {      // 4°
        velocity4.x = velocity4.x * -1;
    }
    if ((location4.y > pos2y - box2size) && (location4.y < pos2y + box2size)) {
        velocity4.y = velocity4.y * -1;
    }
    if ((location5.x > pos2x - box2size) && (location5.x < pos2x + box2size)) {      // 5°
        velocity5.x = velocity5.x * -1;
    }
    if ((location5.y > pos2y - box2size) && (location5.y < pos2y + box2size)) {
        velocity5.y = velocity5.y * -1;
    }
    if ((location6.x > pos2x - box2size) && (location6.x < pos2x + box2size)) {      // 6°
        velocity6.x = velocity6.x * -1;
    }
    if ((location6.y > pos2y - box2size) && (location6.y < pos2y + box2size)) {
        velocity6.y = velocity6.y * -1;
    }
    if ((location7.x > pos2x - box2size) && (location7.x < pos2x + box2size)) {      // 7°
        velocity7.x = velocity7.x * -1;
    }
    if ((location7.y > pos2y - box2size) && (location7.y < pos2y + box2size)) {
        velocity7.y = velocity7.y * -1;
    }
    if ((location8.x > pos2x - box2size) && (location8.x < pos2x + box2size)) {      // 8°
        velocity8.x = velocity8.x * -1;
    }
    if ((location8.y > pos2y - box2size) && (location8.y < pos2y + box2size)) {
        velocity8.y = velocity8.y * -1;
    }

    // DECREMENTO DIMENSIONE PUNTI
    dim = dim - 0.01;
    dim = constrain (dim, 1, 20);
    // RIAVVIO AUTOMATICO
    if (dim == 1) {
      location1.x = posX;
      location1.y = posY;
      location2.x = posX;
      location2.y = posY;
      location3.x = posX;
      location3.y = posY;
      location4.x = posX;
      location4.y = posY;
      location5.x = posX;
      location5.y = posY;
      location6.x = posX;
      location6.y = posY;
      location7.x = posX;
      location7.y = posY;
      location8.x = posX;
      location8.y = posY;
      dim = 20;
    }
  }
}



The code is very bad organised cause I haven't improved myself yet in using arrays..!
Thanks everyone.