在查看寻呼机中手动锁定电话后处理片段

Question

实际上，我正在实现一个 TabLayout，所以在主 MainActivity 中，我加载了 TabFragment 并在 tabFragment（包含两个 fragments）中使用了 ViewPager。

所以问题是当我在 TabLayout 中的片段二上并且屏幕关闭后它将移动到 片段一（默认片段）。那么我该如何解决这个问题

这是 TabFragment 代码：

public class TabFragment extends Fragment {


    public TabFragment() {
        // Required empty public constructor
    }
    public static TabLayout tabLayout;
    public static ViewPager viewPager;
    public static int int_items = 2 ;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View x=inflater.inflate(R.layout.content_main_menu,null);
        tabLayout=(TabLayout) x.findViewById(R.id.tabs);
        viewPager =(ViewPager) x.findViewById(R.id.viewpager);
        setupViewPager(viewPager);
        //viewPager.setAdapter(new MyAdapter(getChildFragmentManager()));
        viewPager.setOffscreenPageLimit(1);
        tabLayout.post(new Runnable() {
            @Override
            public void run() {
                tabLayout.setupWithViewPager(viewPager);
            }
        });
    return x;
    }


    private void setupViewPager(ViewPager viewPager) {
        MyAdapter adapter = new MyAdapter(getChildFragmentManager());
        adapter.addFragment(new HomeFragment(), "Fragment One");
        adapter.addFragment(new Offers(), "fragment Two");

        viewPager.setAdapter(adapter);
    }
    class MyAdapter extends FragmentPagerAdapter{
        private final List<Fragment> mFragmentList = new ArrayList<>();
        private final List<String> mFragmentTitleList = new ArrayList<>();
        public MyAdapter(FragmentManager fm) {
            super(fm);
        }

        @Override
        public Fragment getItem(int position) {
            return mFragmentList.get(position);
        }

        @Override
        public int getCount() {
            return mFragmentList.size();
        }
        public void addFragment(Fragment fragment, String title) {
            mFragmentList.add(fragment);
            mFragmentTitleList.add(title);
        }

        @Override
        public CharSequence getPageTitle(int position) {
            return mFragmentTitleList.get(position);
        }
    }
   }

Answer 1

使用FragmentStatePagerAdapter 而不是FragmentPagerAdapter。阅读文档here。 FragmentStatePagerAdapter 只存储片段的savedInstanceState，并在失去焦点时销毁所有片段。