HW: Many Balls bouncing off Button

mySketch
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// how many balls do you want?
int numCircs = 51;  
​
// Variables for the Circles
// How fast to move it on the X and Y coordinates
float [] SpeedY = new float [numCircs];
float [] SpeedX = new float [numCircs];
​
// Location of Circles 
float [] Ypos = new float [numCircs];
float [] Xpos = new float [numCircs];
​
// Variables to draw the button
float buttonX, buttonY, buttonW, buttonH, ballW;
​
// Has any ball touched the button?
boolean button = false;
​
void setup () {
  size (500, 700);
​
  // align the button to the center of screen
  buttonX = width/2-80;   
  buttonY = height*2/3;   
  buttonH = 40;
  buttonW = 160;
​
  // Size of all Circles
  ballW = 7;
​
  // Start the Circles at a different random point on the screen for X and Y coordinates
  for (int i = 0; i < Ypos.length; i++) { 
    Ypos[i] = random(height); // Start on different parts of the sketch (change to a location or i* 5, to make them appear in a line
    SpeedY[i] = 2;
  }
​
  for (int i = 0; i < Xpos.length; i++) {
    Xpos[i] = random (height);
    SpeedX[i] = 2;
  }
}
void draw () {
​
  // Effect of Button: 
  // 1. change background when button is touched
  if (button) {
    background (#9370A5);   //purple
​
    // 2. draw a triangle when button is hit
    fill (255);
    triangle (200, 300, 250, 200, 300, 300);
  } else {
    background (#FADD00);    // Change BG to yellow
  }
​
  // Draw the button 
  fill(#00FAA0); 
  rect (buttonX, buttonY, buttonW, buttonH); 
​
  // Move balls and check hit detection against the button & sides
  // Use a for loop to cycle through the arrays
  for (int i = 0; i < Ypos.length; i++) {
​
    // Draw the balls at random locations
    fill(#93888C);     // gray
    ellipse ( Xpos[i], Ypos[i], ballW, ballW);// generate new balls 
​
    // make them move 
    Ypos[i] = Ypos[i] + SpeedY[i];    
    Xpos[i] = Xpos[i] + SpeedX[i];    
​
    // hit detection for the Button - Checks if any ball touches the button
    if ((Xpos[i] > buttonX-ballW) && (Xpos[i] < buttonX+buttonW+ballW) && (Ypos[i] > buttonY-ballW) && (Ypos[i] < buttonY+buttonH+ballW)) {
      button = !button; 
​
      // When any ball hits the button make it bounce in opposit direction
      if ( ( Ypos[i] < buttonY) || ( Ypos[i] > buttonY+buttonH)) {   //if it reaches top or bottom, reverse directions 
        SpeedY[i] = SpeedY[i] * -1;     //reverse direction vertically
​
      //make them bounce randomly around
      } else if ((Xpos[i] < buttonX) || (Xpos[i] > buttonX+buttonW)) {   // if it reaches the sides, reverse directions
        SpeedX[i] = SpeedX[i] * -1;     // reverse direction horizontally
      }
    }
    
    //if it hits the walls (top - bottom), reverse 
    if (( Ypos[i]>height) || ( Ypos[i]<0)) { 
      SpeedY[i] = SpeedY[i] * -1;
    } 
    //if it hits the walls (sides), reverse 
    if ((Xpos[i]>width) || (Xpos[i]<0)) {
      SpeedX[i] = SpeedX[i] * -1;
    }
  }
}