Re : Serial Library: Connect and disconnect

1. createConnection() .
2. closeConnection() .

Within closeConnection() , make myPort = null; as also a flag to indicate it's not active anymore:

import processing.serial.*;
Serial myPort;

void draw() {
  if (myPort == null)  createConnection();
}

void createConnection() {
  myPort = new Serial(this, Serial.list()[0], 9600);
}

void closeConnection() {
  myPort.stop();
  myPort = null;
}