Tab与viewpager之间的转化frament

   list = new ArrayList<>();
        list.add("动态");
        list.add("热门");
        list.add("发现");

        //设置适配器
        viewPager.setAdapter(new FragmentPagerAdapter(getChildFragmentManager()) {
            @Override
            public CharSequence getPageTitle(int position) {
                return list.get(position);
            }

            @Override
            public Fragment getItem(int position) {
                Fragment fragment =null;

                switch (position){
                    case 0:
                        fragment = new FragmentDongTai();
                        break;
                    case 1:
                        fragment = new FragmentReMen();
                        break;
                    case 2:
                        fragment = new FragmentFaXian();
                        break;

                    default:
                        break;
                }

                return fragment;
            }

            @Override
            public int getCount() {
                return list.size();
            }
        });

        //关联
        tabLayout.setupWithViewPager(viewPager);
    }