Many balls bouncing off the walls

int numOfBalls = 300;

int ballMin = 3;

int ballMax = 5;

​

float[] ballsX = new float[numOfBalls];

float[] ballsY = new float[numOfBalls];

float[] xChange = new float[numOfBalls];

float[] yChange = new float[numOfBalls];

float[] ballSize = new float[numOfBalls];

color[] ballColors = new color[numOfBalls];

​

void setup(){

  size(500, 500);

  background(0);

  smooth();

  noStroke();

  colorMode(HSB, 100, 100, 100, 100);

  fill(0);

  for(int i = 0; i < numOfBalls; i++){

    ballsX[i] = random(10, width-10);

    ballsY[i] = random(10, height-10);

    xChange[i] = random(-5, 5);

    yChange[i] = random(-5, 5);

    ballSize[i] = random(ballMin, ballMax);

    ballColors[i] = int(random(0, 100));

  }

}

​

void draw(){

    background(100);

    for(int i = 0; i < numOfBalls; i++){

      if((ballsX[i] < 5) || (ballsX[i] > width - 5)){

        xChange[i] = -xChange[i];

      }

      if((ballsY[i] < 5) || (ballsY[i] > height - 5)){

        yChange[i] = -yChange[i];

      }

      fill(ballColors[i], 100, 100);

      ellipse(ballsX[i], ballsY[i], ballSize[i], ballSize[i]);

      ballsX[i] = ballsX[i] + xChange[i];

      ballsY[i] = ballsY[i] + yChange[i];

    }

}

​