策略模式（Strategy）

interface Sort{
        void sort();
    }
    class QuickSort implements Sort{
        @Override
        public void sort() {
            System.out.print("快排");
        }
    }
    class BubbleSort implements Sort{
        @Override
        public void sort() {
            System.out.print("冒泡");
        }
    }
    class Strategy{
        Sort mSort;
        public void sort(int[] res){
            if (res.length > 1000 * 1000){
                mSort = new QuickSort();
            }else {
                mSort = new BubbleSort();
            }
            mSort.sort();
        }
    }