@Override
	public int compareTo(Object o) {
		Double particle = fitness;
		Double other = (((ParticleFitness)o).getFitness());
		int result = particle.compareTo(other);
		if(result != 0){
			return result;
		}else{
			Integer particleIndex = index;
			Integer otherIndex = ((ParticleFitness)o).getIndex();
			return particleIndex.compareTo(otherIndex);
		}
	}