Custom Listview not refreshed on fragment back

问题:

I have one custom list view adapter loading contact list. When I open app, contacts are loading perfectly , but once I came back after scrolling to Preference Fragment, listview is empty. Though Data is collected by calling Inner class LoadContact but nothing in listview. There are three fragments. pls guide. Code for Fragment (tab1). If u see I added adapter initialization in oncreatview as otherwise on back tab I m getting Null point exception. m I did correct here?

public class Requestor extends Fragment {

    EditText targetdevice;
    ListView recentlist;
    List<String> recentlistarray = new ArrayList<>();
    ArrayAdapter arrayAdapter;
    Dialog dialog;
    String targetmobile, requesttype;
    private TextView tex1, remotelocation;
    int deviceid;
    LinearLayout contactlayout;
    RadioButton radiorecent, radiocontact;

   ArrayList<ContactListSelectUser> contactListSelectUsers;
    List<ContactListSelectUser> temp;
    // Contact List
    ListView listView;

    // Cursor to load contacts list
    Cursor phones, email;

    // Pop up
    ContentResolver resolver;
    SearchView search;
    ContactListAdapter adapter;


    @Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        LoadContact loadContact = new LoadContact();
        loadContact.execute();
    }

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) throws NullPointerException{
        View view = inflater.inflate(R.layout.autolocationrequester, container, false);

        targetdevice = (EditText) view.findViewById(R.id.targetdevice);
        recentlist = (ListView) view.findViewById(R.id.targetlist);
        remotelocation = (TextView) view.findViewById(R.id.remotelocationreq);
        tex1 = (TextView) view.findViewById(R.id.tex1);
        requesttype = "Location";
        radiorecent = (RadioButton) view.findViewById(R.id.radiorecent);
        radiocontact = (RadioButton) view.findViewById(R.id.radiocontact);
        contactlayout = (LinearLayout) view.findViewById(R.id.contactlayout);
        tex1 = (TextView) view.findViewById(R.id.tex1);
        recentlist.setVisibility(View.GONE);
        contactlayout.setVisibility(View.GONE);
        tex1.setVisibility(View.GONE);

        contactListSelectUsers = new ArrayList<ContactListSelectUser>();
        resolver = getActivity().getApplicationContext().getContentResolver();
        listView = (ListView) view.findViewById(R.id.contacts_list);
       adapter = new ContactListAdapter(contactListSelectUsers, getActivity().getApplicationContext());
        phones = getActivity().getApplicationContext().getContentResolver().query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI, null, null, null, ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME + " ASC");


        LoadContact loadContact = new LoadContact();
        loadContact.execute();

        search = (SearchView) view.findViewById(R.id.searchView);

        //*** setOnQueryTextListener ***
        search.setOnQueryTextListener(new SearchView.OnQueryTextListener() {

            @Override
            public boolean onQueryTextSubmit(String query) {
                // TODO Auto-generated method stub

                return false;
            }

            @Override
            public boolean onQueryTextChange(String newText) {
                // TODO Auto-generated method stub
                adapter.filter(newText);
                return false;
            }

        });
        SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(getActivity().getApplicationContext());
        deviceid = Integer.parseInt(sharedPreferences.getString("deviceid", ""));

        remotelocation.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                arrayAdapter = new ArrayAdapter(getActivity().getApplicationContext(), android.R.layout.simple_list_item_1, recentlistarray);
                recentlist.setAdapter(arrayAdapter);
                targetmobile = targetdevice.getText().toString();
                new sendreqloc().execute();
                targetdevice.setText("");

                // Popup.smallpopup("hi", getApplicationContext());
            }
        });

        radiorecent.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                recentlist.setVisibility(View.VISIBLE);
                tex1.setVisibility(View.VISIBLE);
                contactlayout.setVisibility(View.GONE);
                targetdevice.setText("");
            }
        });


        radiocontact.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                recentlist.setVisibility(View.GONE);
                contactlayout.setVisibility(View.VISIBLE);
                tex1.setVisibility(View.GONE);
                targetdevice.setText("");
                LoadContact loadContact = new LoadContact();
                loadContact.execute();

            }
        });

        return view;
    }


    public class LoadContact extends AsyncTask<Void, Void, Void> {
        @Override
        protected void onPreExecute() {

            super.onPreExecute();

        }

        @Override
        protected Void doInBackground(Void... voids) {
            // Get Contact list from Phone

            if (phones != null) {
                Log.e("count", "" + phones.getCount());
                if (phones.getCount() == 0) {
                    //       Toast.makeText(Requestor.this, "No contacts in your contact list.", Toast.LENGTH_LONG).show();
                }

                while (phones.moveToNext()) {
                  Log.d("Contact Class Called","");
                    Bitmap bit_thumb = null;
                    String id = phones.getString(phones.getColumnIndex(ContactsContract.CommonDataKinds.Phone.CONTACT_ID));
                    String name = phones.getString(phones.getColumnIndex(ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME));
                    String phoneNumber = phones.getString(phones.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER));
                    //    String EmailAddr = phones.getString(phones.getColumnIndex(ContactsContract.CommonDataKinds.Email.DATA2));
                    String image_thumb = phones.getString(phones.getColumnIndex(ContactsContract.CommonDataKinds.Phone.PHOTO_THUMBNAIL_URI));
                    try {
                        if (image_thumb != null) {
                            bit_thumb = MediaStore.Images.Media.getBitmap(resolver, Uri.parse(image_thumb));
                        } else {
                            Log.e("No Image Thumb", "--------------");
                        }
                    } catch (IOException e) {
                        e.printStackTrace();
                    }

                    ContactListSelectUser contactListSelectUser = new ContactListSelectUser();
                    contactListSelectUser.setThumb(bit_thumb);
                    contactListSelectUser.setName(name);
                    contactListSelectUser.setPhone(phoneNumber);
                    contactListSelectUser.setEmail(id);
                    // contactListSelectUser.setCheckedBox(false);
                    // if (!contactListSelectUsers.contains(contactListSelectUser.getPhone())) {
                    contactListSelectUsers.add(contactListSelectUser);
                    //}

                }
            } else {
                Log.e("Cursor close 1", "----------------");
            }
            //phones.close();
            //System.out.println(contactListSelectUsers.size());
            return null;
        }

        @Override
        protected void onPostExecute(Void aVoid) {
            super.onPostExecute(aVoid);
            adapter = new ContactListAdapter(contactListSelectUsers, getActivity());
            listView.setAdapter(adapter);

            // Select item on listclick
            listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                @Override
                public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {

                    Log.e("search", "here---------------- listener");

                    ContactListSelectUser data = contactListSelectUsers.get(i);
                    targetdevice.setText(data.getPhone());
                }
            });

            listView.setFastScrollEnabled(true);
        }
    }

   /* @Override
    protected void onStop() {
        super.onStop();
        phones.close();
    }*/
}

Custom Adapter class code:

    public class ContactListAdapter extends BaseAdapter implements Filterable {

        public List<ContactListSelectUser> _data;


 private ArrayList<ContactListSelectUser> arraylist;
    Context _c;
    ViewHolder v;
    RoundImage roundedImage;
    private Filter filter = new CustomFilter();

    public ContactListAdapter(List<ContactListSelectUser> contactListSelectUsers, Context context) {
        _data = contactListSelectUsers;
        _c = context;
        this.arraylist = new ArrayList<ContactListSelectUser>();
        this.arraylist.addAll(_data);
    }

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

    @Override
    public Object getItem(int i) {
        return _data.get(i);
    }

    @Override
    public long getItemId(int i) {
        return i;
    }

    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
    @Override
    public View getView(int i, View convertView, ViewGroup viewGroup) {
        View view = convertView;
        if (view == null) {
            LayoutInflater li = (LayoutInflater) _c.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            view = li.inflate(R.layout.contact_info, null);
            Log.e("Inside", "here--------------------------- In view1");
        } else {
            view = convertView;
            Log.e("Inside", "here--------------------------- In view2");
        }

        v = new ViewHolder();

        v.title = (TextView) view.findViewById(R.id.name);
        //   v.check = (CheckBox) view.findViewById(R.id.check);
        v.phone = (TextView) view.findViewById(R.id.no);
        v.imageView = (ImageView) view.findViewById(R.id.pic);

        final ContactListSelectUser data = (ContactListSelectUser) _data.get(i);
        v.title.setText(data.getName());
        //    v.check.setChecked(data.getCheckedBox());
        v.phone.setText(data.getPhone());

        // Set image if exists
        try {

            if (data.getThumb() != null) {
                v.imageView.setImageBitmap(data.getThumb());
            } else {
                v.imageView.setImageResource(R.mipmap.ic_launcher);
            }
            // Seting round image
            Bitmap bm = BitmapFactory.decodeResource(view.getResources(), R.mipmap.ic_launcher); // Load default image
            roundedImage = new RoundImage(bm);
            v.imageView.setImageDrawable(roundedImage);
        } catch (OutOfMemoryError e) {
            // Add default picture
            v.imageView.setImageDrawable(this._c.getDrawable(R.mipmap.ic_launcher));
            e.printStackTrace();
        }

        Log.e("Image Thumb", "--------------" + data.getThumb());

        /*// Set check box listener android
        v.check.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                CheckBox checkBox = (CheckBox) view;
                if (checkBox.isChecked()) {
                    data.setCheckedBox(true);
                  } else {
                    data.setCheckedBox(false);
                }
            }
        });*/

        view.setTag(data);
        return view;
    }

    // Filter Class
    public void filter(String charText) {
        charText = charText.toLowerCase(Locale.getDefault());
        _data.clear();
        if (charText.length() == 0) {
            _data.addAll(arraylist);
        } else {
            for (ContactListSelectUser wp : arraylist) {
                if (wp.getName().toLowerCase(Locale.getDefault())
                        .contains(charText)) {
                    _data.add(wp);
                }
            }
        }
        notifyDataSetChanged();
    }

    @Override
    public Filter getFilter() {
        return filter;
    }

    static class ViewHolder {
        ImageView imageView;
        TextView title, phone;
        CheckBox check;
    }

    private class CustomFilter extends Filter {


        @Override
        protected FilterResults performFiltering(CharSequence charSequence) {
            _data.clear();

            FilterResults filterResults = new FilterResults();
            filterResults.values = _data;
            filterResults.count = _data.size();
            return filterResults;
        }

        @Override
        protected void publishResults(CharSequence charSequence, FilterResults filterResults) {
            if (filterResults.count > 0) {
                notifyDataSetChanged();
            } else {
                notifyDataSetInvalidated();
            }
        }
    }
}

below is logcat where u can see data is fetched while I choose back fragment but not set to listview.

E/Inside: here--------------------------- In view1
E/Image Thumb: --------------null
E/Inside: here--------------------------- In view1
E/Image Thumb: --------------null
I/TextInputLayout: EditText added is not a TextInputEditText. Please switch to using that class instead.
E/count: 2
E/No Image Thumb: --------------
E/No Image Thumb: --------------
E/count: 2
E/count: 2

回答1:

implements Filterable in BaseAdapter

public class ContactListAdapter extends BaseAdapter implements Filterable

and add value :

private Filter filter = new CustomFilter();

and create class in your baseAdapter:

private class CustomFilter extends Filter {
        @Override
        protected FilterResults performFiltering(CharSequence constraint) {
          _data.clear();

        if (arraylist != null && constraint != null) {
            for (int i = 0; i < arraylist.size(); i++) {
                if (arraylist.get(i).toString().toLowerCase().contains(constraint)) {
                    _data.add(arraylist.get(i));
                }
            }
        }

    FilterResults results = new FilterResults();
            results.values = _data;
            results.count = _data.size();
            return results;
        }

        @Override
        protected void publishResults(CharSequence constraint, FilterResults results) {
            if (results.count > 0) {
                notifyDataSetChanged();
            } else {
                notifyDataSetInvalidated();
            }
        }
    }

add in your baseAdapter class:

@Override
public Filter getFilter() {
    return filter;
}

my adapter for example:

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.Filter;
import android.widget.Filterable;
import android.widget.TextView;

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

public class CustomArrayAdapter extends BaseAdapter implements Filterable{
    private LayoutInflater mInflater;
    private final Context context;
    private List<String> mItems;
    private Filter filter = new CustomFilter();
    private ArrayList<String>mItemsSuggestion = new ArrayList<String>();

    public CustomArrayAdapter(Context context, String[] values) {
        this.context = context;
        mItems = Arrays.asList(values);
    }

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

    @Override
    public Object getItem(int position) {
        return mItemsSuggestion.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        View oneView = mInflater.inflate(R.layout.towar_list, parent, false);
        TextView text = (TextView)oneView.findViewById(R.id.towaryAllList);
        text.setText(mItemsSuggestion.get(position).toString());
        return oneView;
    }


    @Override
    public Filter getFilter() {
        return filter;
    }

    private class CustomFilter extends Filter {
        @Override
        protected FilterResults performFiltering(CharSequence constraint) {
            mItemsSuggestion.clear();

            if (mItems != null && constraint != null) {
                for (int i = 0; i < mItems.size(); i++) {
                    if (mItems.get(i).toString().toLowerCase().contains(constraint)) {
                        mItemsSuggestion.add(mItems.get(i));
                    }
                }
            }
            FilterResults results = new FilterResults();
            results.values = mItemsSuggestion;
            results.count = mItemsSuggestion.size();
            return results;
        }

        @Override
        protected void publishResults(CharSequence constraint, FilterResults results) {
            if (results.count > 0) {
                notifyDataSetChanged();
            } else {
                notifyDataSetInvalidated();
            }
        }
    }
}

回答2:

I solved it now. The issue was only placing search view code in radiocontact on click listeners instead of in createview method directly.