private static void mergeSort(ArrayList<objeto> items){

        if (items.size() == 1) {
            //insert(items);
        }
        else{
            int n = items.size() - 1;
            int k = n /2;
            ArrayList<objeto> U = new ArrayList<objeto>();
            ArrayList<objeto> V = new ArrayList<objeto>();
            copy(items,U,0,k);
            copy(items,V,k+1,n);

            mergeSort(U);
            mergeSort(V);

            merge(U,V,items);
        }
    }

    private static void copy(ArrayList<objeto> src,ArrayList<objeto> dest, int i,int j){

        for (int ini=i; ini<= j;ini++){

            dest.add(src.remove(0));
        }
    }

    private static void merge(ArrayList<objeto> src1,ArrayList<objeto> src2,ArrayList<objeto> out){

        while (!src1.isEmpty() && !src2.isEmpty()){

            if (src1.get(0).getAverage() > src2.get(0).getAverage()){

                out.add(src1.remove(0));
            }
            else out.add(src2.remove(0));
        }

        while (!src1.isEmpty()){

            out.add(src1.remove(0));
        }

        while (!src2.isEmpty()){

            out.add(src2.remove(0));
        }
    }