Android片段更新问题

Question

I have three fragments using tablayout. Problem is that i save data in fragment one and wants to show data in second fragment but second fragment not update when click or swipe to second fragment because fragment not create again due to default offsetlimit 1. When i restart app again the data is showed. Any solution highly appreciated.

//My MainActivity code here

public class MainActivity extends AppCompatActivity
{
    private Toolbar toolbar;
    private TabLayout tabLayout;
    private ViewPager viewPager;
    private int[] tabIcons = {
            R.drawable.calender,
            R.drawable.favourite,
            R.drawable.setting_icon
    };

    PagerAdapter pagerAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        getSupportActionBar().setDisplayShowTitleEnabled(false);

        viewPager = (ViewPager) findViewById(R.id.viewpager);
        pagerAdapter =  new PagerAdapter(getSupportFragmentManager(), MainActivity.this);
        viewPager.setAdapter(pagerAdapter);
       // viewPager.setOffscreenPageLimit(0);

        tabLayout = (TabLayout) findViewById(R.id.tab_layout);
        tabLayout.setupWithViewPager(viewPager);
        tabLayout.getTabAt(0).setIcon(R.drawable.calender_hover);


        for (int i = 0; i < tabLayout.getTabCount(); i++)
        {
            TabLayout.Tab tab = tabLayout.getTabAt(i);
            tab.setCustomView(pagerAdapter.getTabView(i));
        }

    }

    class PagerAdapter extends FragmentStatePagerAdapter
    {

        String tabTitles[] = new String[] { "Tab One", "Tab Two", "Tab Three", };

        private int[] tabIcons = { R.drawable.tab_selector_calendar, R.drawable.tab_selector_favorite, R.drawable.tab_selector_settings
        };

        Context context;

        public PagerAdapter(FragmentManager fm, Context context) {
            super(fm);
            this.context = context;
        }

        @Override
        public int getCount() {
            return tabTitles.length;
        }

        @Override
        public Fragment getItem(int position) {

            switch (position) {
                case 0:
                    return new FragmentAyah();
                case 1:
                    return new FragmentFavorite();
                case 2:
                    return new FragmentSettings();
            }

            return null;
        }

        @Override
        public CharSequence getPageTitle(int position) {
            // Generate title based on item position
           // return tabTitles[position];
            return null;
        }

        public View getTabView(int position) {
            View tab = LayoutInflater.from(MainActivity.this).inflate(R.layout.custom_tab, null);
            ImageView imgView = (ImageView) tab.findViewById(R.id.imgView);

            imgView.setBackgroundResource(tabIcons[position]);


            //  TextView tv = (TextView) tab.findViewById(R.id.custom_text);
            // tv.setText(tabTitles[position]);
            return tab;
        }

    }

}
 and Fragment code

//Tab 1 FragmentAyah code here

public class FragmentAyah extends Fragment
{
    private RecyclerView recyclerView;
    private List<Ayat> ayatList = new ArrayList<>();
    private AyatAdapter ayatAdapter;
    DBHelper dbHelperA;
    List<AyatVariables> datalist = new ArrayList<AyatVariables>();
    String formattedDate = "";
    SimpleDateFormat df;
    private Calendar c;

    public FragmentAyah()
    {
        // Required empty public constructor
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
    {
        // Inflate the layout for this fragment
        ViewGroup root = (ViewGroup) inflater.inflate(R.layout.fragment_ayah, null);

        recyclerView = (RecyclerView) root.findViewById(R.id.recycler_view);
        ayatAdapter = new AyatAdapter(ayatList,getActivity());

        dbHelperA = new DBHelper(getActivity());

        c = Calendar.getInstance();
        df = new SimpleDateFormat("yyyy-MM-dd");
        formattedDate = df.format(c.getTime());

        getAllValuesFromDB();

        RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(getActivity());
        recyclerView.setLayoutManager(mLayoutManager);
        recyclerView.setItemAnimator(new DefaultItemAnimator());
        recyclerView.addItemDecoration(new SimpleDividerItemDecoration(getActivity()));
        recyclerView.setAdapter(ayatAdapter);
        ayatAdapter.notifyDataSetChanged();

        return root;
    }

    private void prepareMovieData() {
        // AyatVariables ayat = new AyatVariables("Surah Al-Fatiha","Ayat","1",":11","Translation11");
for (int i = 0; i < datalist.size(); i++) {
                    Ayat ayat = new Ayat(datalist.get(i).getID(), datalist.get(i).getSURAH_NAME(),
                            datalist.get(i).getTEXTS(), datalist.get(i).getSURAH(),
                            datalist.get(i).getAYA(), datalist.get(i).getEN_TRANSLATION(),
                            datalist.get(i).getDATES());

                    ayatList.add(ayat);

                ayatAdapter.notifyDataSetChanged();
        }
    }

    @Override
    public void onDestroyView()
    {
        super.onDestroyView();
        Log.e("onDestroyView======>","onDestroyView");
        ayatAdapter.notifyDataSetChanged();
        ayatList.clear();
    }

    public void getAllValuesFromDB()
    {
        try {
            dbHelperA.createDataBase();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        datalist.clear();
        datalist = dbHelperA.getDataWithAllTranslation(formattedDate);
       // Log.e("datasize=========>",""+datalist.size());
        dbHelperA.close();

        prepareMovieData();
    }

}

//Tab 2 FragmentFavorite code here

public class FragmentFavorite extends Fragment {

    private RecyclerView recyclerView;
    private List<FAyat> ayatList = new ArrayList<>();
    private AyatFAdapter ayatAdapter;
    DBHelper dbHelperA;
    DBHelper2 dbHelperF;
    List<AyatVariables> datalist = new ArrayList<AyatVariables>();
    List<FavVariables> fVar = new ArrayList<FavVariables>();
    String formattedDate = "";
    SimpleDateFormat df;
    private Calendar c;

    public FragmentFavorite() {
        // Required empty public constructor
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        ViewGroup root = (ViewGroup) inflater.inflate(R.layout.fragment_favorits, null);
        recyclerView = (RecyclerView) root.findViewById(R.id.frecycler_view);
        ayatAdapter = new AyatFAdapter(ayatList, getActivity());

        dbHelperA = new DBHelper(getActivity());
        dbHelperF = new DBHelper2(getActivity());

        c = Calendar.getInstance();
        df = new SimpleDateFormat("yyyy-MM-dd");
        formattedDate = df.format(c.getTime());

        getAllValuesFromDB();

        RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(getActivity());
        recyclerView.setLayoutManager(mLayoutManager);
        recyclerView.setItemAnimator(new DefaultItemAnimator());
        recyclerView.setAdapter(ayatAdapter);
        ayatAdapter.notifyDataSetChanged();

        return root;
    }

    private void prepareMovieData() {
        // AyatVariables ayat = new AyatVariables("Surah Al-Fatiha","Ayat","1",":11","Translation11");

       for (int i = 0; i < datalist.size(); i++) {
                    FAyat ayat = new FAyat(datalist.get(i).getID(), datalist.get(i).getSURAH_NAME(),
                            datalist.get(i).getTEXTS(), datalist.get(i).getSURAH(),
                            datalist.get(i).getAYA(), datalist.get(i).getEN_TRANSLATION(),
                            datalist.get(i).getDATES());

                    ayatList.add(ayat);

                            ayatAdapter.notifyDataSetChanged();
        }
    }

    @Override
    public void onDestroyView() {
        super.onDestroyView();
        ayatList.clear();
    }

    public void getAllValuesFromDB()
    {
        getIDfromFav();

        try {
            dbHelperA.createDataBase();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        for (int i = 0; i<fVar.size();i++) {
           // datalist = dbHelperA.getAllDataForFav(fVar.get(i).getFavID());
            datalist.add(dbHelperA.getAllDataForFav(fVar.get(i).getFavID()));

            Log.e("datasize=========>",""+datalist.size());
        }
        dbHelperA.close();

        prepareMovieData();
    }

    public void getIDfromFav()
    {
        fVar.clear();
        fVar = dbHelperF.getAllFav();
        Log.e("fVar--size",""+fVar.size());
        dbHelperF.close();
    }

}

Answer 1

You can like the non-coupled class with data changes using many ways. Here is a sample code with Broadcast Receiver:

In your Fragment 1, when there is some data changed, do this,

Intent intent = new Intent("my-event");
// add data
intent.putExtra("message", "data"); // This data can be anything which is changed. You can also use SharedPreference and can remove that after using it
LocalBroadcastManager.getInstance(this).sendBroadcast(intent);

Now, in the Fragment 2, First you have to register this fragment as a receiver,

@Override
public void onResume() {
super.onResume();

// Register mMessageReceiver to receive messages.
LocalBroadcastManager.getInstance(this).registerReceiver(mMessageReceiver, new IntentFilter("my-event"));
}

Now, after registering, you have to handle the receive intent

// handler for received Intents for the "my-event" event 
private BroadcastReceiver mMessageReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
// Extract data included in the Intent or from SharedPreference in that case
String message = intent.getStringExtra("message");
Log.d("receiver", "Got message: " + message);
// In your case, you have to update the views or values in this method
 }
};

And pause the listening onPause to avoid null context

@Override
protected void onPause() {
// Unregister since the fragment is not visible
LocalBroadcastManager.getInstance(this).unregisterReceiver(mMessageReceiver);
super.onPause();
}