int max = individuals.size()/2;
for (int i = 0; i < max; i++) {
            int index1 = -1;
            int index2 = -1;
            while (index1 == index2) {

                index1 = random.nextInt(individuals.size());
                index2 = random.nextInt(individuals.size());
            }

            Individual individual1 = individuals.remove(index1);
            Individual individual2 = individuals.remove(index2);
            //krzyżowanie
 }