[android] Refresh or force redraw the fragment

I have a fragment that inflates an xml layout. My requirement is to update the text size on all my views inside my fragment when my Activity is resumed. I tried

    fragment.getView().invalidate();

which didn't seem to do the work. I also tried

    fragment.getView().requestLayout();

which didn't work either.

On another activity, I have a ListFragment which needs to do the same thing. I tried

    listfragment.getListView().invalidate();

which did the trick, refreshing my list view and redrawing all the items inside it.

I don't understand why one works but not the other.

I have also seen people recommending initiating a fragment transaction and replacing the current fragment with a new one, and it has kept me wondering

1. Why should I create a whole new fragment and replace my current fragment when all I need is to refresh the text on the views that my fragment contains.

2. Fragment transaction method will prevent me from defining my fragment in the layout xml of my activity and I will have to programatically insert the fragment at the right position.

Is there any simple approach to this?

Use the following code for refreshing fragment again:

FragmentTransaction ftr = getFragmentManager().beginTransaction();                          
ftr.detach(EnterYourFragmentName.this).attach(EnterYourFragmentName.this).commit();

In my case, detach and attach worked:

 getSupportFragmentManager()
   .beginTransaction()
   .detach(contentFragment)
   .attach(contentFragment)
   .commit();

detach().detach() not working after support library update 25.1.0 (may be earlier). This solution works fine after update:

getSupportFragmentManager()
    .beginTransaction()
    .detach(oldFragment)
    .commitNowAllowingStateLoss();

getSupportFragmentManager()
    .beginTransaction()
    .attach(oldFragment)
    .commitAllowingStateLoss();

I am using remove and replace both for refreshing content of Fragment like

final FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.remove(resetFragment).commit();
fragmentTransaction.replace(R.id.frame_container,resetFragment).commit();

To solve the problem, I use this:

Fragment frg = null;
frg = getFragmentManager().findFragmentByTag("Feedback");
final android.support.v4.app.FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.detach(frg);
ft.attach(frg);
ft.commit();

let us see the below source code. Here fragment name is DirectoryOfEbooks. After completion of the background task, i am the replacing the frame with current fragment. so the fragment gets refreshed and reloads its data

    import android.app.ProgressDialog;
    import android.content.DialogInterface;
    import android.database.Cursor;
    import android.database.sqlite.SQLiteDatabase;
    import android.os.AsyncTask;
    import android.os.Bundle;
    import android.support.v4.app.Fragment;
    import android.support.v4.app.FragmentTransaction;
    import android.support.v4.view.MenuItemCompat;
    import android.support.v7.app.AlertDialog;
    import android.support.v7.widget.DefaultItemAnimator;
    import android.support.v7.widget.GridLayoutManager;
    import android.support.v7.widget.LinearLayoutManager;
    import android.support.v7.widget.RecyclerView;
    import android.support.v7.widget.SearchView;
    import android.view.LayoutInflater;
    import android.view.Menu;
    import android.view.MenuInflater;
    import android.view.MenuItem;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.TextView;
    import android.widget.Toast;

    import com.github.mikephil.charting.data.LineRadarDataSet;

    import java.util.ArrayList;
    import java.util.List;


    /**
     * A simple {@link Fragment} subclass.
     */
    public class DirectoryOfEbooks extends Fragment {

        RecyclerView recyclerView;
        branchesAdapter adapter;
        LinearLayoutManager linearLayoutManager;
        Cursor c;
        FragmentTransaction fragmentTransaction;
        SQLiteDatabase db;
        List<branch_sync> directoryarraylist;

        public DirectoryOfEbooks() {
            // Required empty public constructor
        }
        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {


            View view = inflater.inflate(R.layout.fragment_directory_of_ebooks, container, false);
            directoryarraylist = new ArrayList<>();
            db = getActivity().openOrCreateDatabase("notify", android.content.Context.MODE_PRIVATE, null);
            c = db.rawQuery("select * FROM branch; ", null);

            if (c.getCount() != 0) {
                c.moveToFirst();
                while (true) {
                    //String ISBN = c.getString(c.getColumnIndex("ISBN"));
                    String branch = c.getString(c.getColumnIndex("branch"));

                    branch_sync branchSync = new branch_sync(branch);
                    directoryarraylist.add(branchSync);
                    if (c.isLast())
                        break;
                    else
                        c.moveToNext();
                }

                recyclerView = (RecyclerView) view.findViewById(R.id.directoryOfEbooks);
                adapter = new branchesAdapter(directoryarraylist, this.getContext());
                adapter.setHasStableIds(true);
                recyclerView.setItemAnimator(new DefaultItemAnimator());
                System.out.println("ebooks");
                recyclerView.setHasFixedSize(true);
                linearLayoutManager = new LinearLayoutManager(this.getContext());
                recyclerView.setLayoutManager(linearLayoutManager);
                recyclerView.setAdapter(adapter);
                System.out.println(adapter.getItemCount()+"adpater count");

            }
            // Inflate the layout for this fragment
            return view;
        }
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            //setContentView(R.layout.fragment_books);
            setHasOptionsMenu(true);
        }
        public void onPrepareOptionsMenu(Menu menu) {
            MenuInflater inflater = getActivity().getMenuInflater();
            inflater.inflate(R.menu.refresh, menu);
            MenuItem menuItem = menu.findItem(R.id.refresh1);
            menuItem.setVisible(true);
        }
        public boolean onOptionsItemSelected(MenuItem item) {
            if (item.getItemId() == R.id.refresh1) {
                new AlertDialog.Builder(getContext()).setMessage("Refresh takes more than a Minute").setPositiveButton("Refresh Now", new DialogInterface.OnClickListener() {

                    public void onClick(DialogInterface dialog, int which) {

                        new refreshebooks().execute();
                    }
                }).setNegativeButton("Refresh Later", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int which) {

                    }
                }).setCancelable(false).show();

            }
            return super.onOptionsItemSelected(item);
        }

    public class refreshebooks extends AsyncTask<String,String,String>{
        ProgressDialog progressDialog;
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
          progressDialog=new ProgressDialog(getContext());
            progressDialog.setMessage("\tRefreshing Ebooks .....");
            progressDialog.setCancelable(false);
            progressDialog.show();
        }

        @Override
        protected String doInBackground(String... params) {
            Ebooksync syncEbooks=new Ebooksync();
            String status=syncEbooks.syncdata(getContext());
            return status;

        }

        @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);
            if(s.equals("error")){
                progressDialog.dismiss();
                Toast.makeText(getContext(),"Refresh Failed",Toast.LENGTH_SHORT).show();
            }
            else{
                fragmentTransaction = getActivity().getSupportFragmentManager().beginTransaction();
                fragmentTransaction.replace(R.id.mainframe, new DirectoryOfEbooks());
                fragmentTransaction.commit();
                progressDialog.dismiss();
                adapter.notifyDataSetChanged();
                Toast.makeText(getContext(),"Refresh Successfull",Toast.LENGTH_SHORT).show();
            }

        }
    }

    }

This worked for me from within Fragment:

Fragment frg = null;
Class fragmentClass;
fragmentClass = MainFragment.class;

try {
    frg = (android.support.v4.app.Fragment)     
    fragmentClass.newInstance();
} catch(Exception ex) {
    ex.printStackTrace();
}

getFragmentManager()
    .beginTransaction()
    .replace(R.id.flContent, frg)
    .commit();

I do not think there is a method for that. The fragment rebuilds it's UI on onCreateView()... but that happens when the fragment is created or recreated.

You'll have to implement your own updateUI method or where you will specify what elements and how they should update. It's rather a good practice, since you need to do that when the fragment is created anyway.

However if this is not enough you could do something like replacing fragment with the same one forcing it to call onCreateView()

FragmentTransaction tr = getFragmentManager().beginTransaction();
tr.replace(R.id.your_fragment_container, yourFragmentInstance);
tr.commit()

NOTE

To refresh ListView you need to call notifyDataSetChanged() on the ListView's adapter.