Fired up Processing for the first time in a while, for some quick prototyping, and my brain has gone awry. Could somebody point me in the right direction for the following:

So, I have a load of 'Sphere' objects, randomly bunged on the stage. I then want to attach user actions to individual elements ie. click on a sphere and it does something like increase in size (for now).

Here's my code:

//Set up object arrays

int numOfspheresArr = 20;

Sphere[] spheresArr = new Sphere[numOfspheresArr];

void setup(){

  size(800, 600);

  for (int i = 0; i < spheresArr.length; i++){

    spheresArr[i] = new Sphere (color(random(0,255),0,0,60),50,random(0, width), random(0, height));

  }

}

void draw(){

  background(255);

  for(int i = 0; i < spheresArr.length; i++){

    spheresArr[i].display();

    spheresArr[i].hitTest();

  }

}

// Class : Begin

class Sphere{

  color c;

  float diameter;

  float xpos;

  float ypos;

  

  Sphere(color _c, float _diameter, float _xpos, float _ypos){

    c = _c;

    diameter = _diameter;

    xpos = _xpos;

    ypos = _ypos;

  }

  

  void display(){

    noStroke();

    smooth();

    fill(c);

    ellipseMode(CENTER);

    ellipse(xpos, ypos, diameter, diameter);

  }

  

  void hitTest(){

     if (mousePressed == true){

     this.diameter ++;

     println(this + " object is being clicked");

    }

  }  

}

// Class : End

What am I missing here again? Soz for the gormless post!