public static double nextExponential(double lambda){
synchronized (random) {
    return -1.0 * Math.log(1 - random.nextDouble()) / lambda;
  }
}

public static double nextExponential ( double lambda ) { synchronized ( random ) { return - 1.0 * Math . log ( 1 - random . nextDouble ( ) ) / lambda ; } }
access a default instance of this class , access is synchronized
