Data not being displayed when switching between tabs

Question

I am using the https://github.com/astuetz/PagerSlidingTabStrip/ library. My activity consists of 3 "tabs" and each of these tabs has it's own fragment.

The problem is that whenever I load tab 3, all the data in tab 1 is lost and will not be refreshed.

All 3 fragments are filled with a listview and have similar code.

I can't figure out why it keeps happening, but it seems as if whenever I load a tab that is not the direct "neighbour" of the currently selected tab, the currently selected tab gets unloaded.

Basically, I have 3 tabs. If I load tab 3, tab 1 unloads and doesn't reload. Tab 2 always remains filled (I assume because tab 2 is always either a] the neighbour of tab 1 or b] the neighbour of tab 3).

OrdersActivity.java

package nl.*.android.order;


    import android.content.Intent;
    import android.support.v4.app.Fragment;
    import android.support.v4.view.ViewPager;

    import com.astuetz.PagerSlidingTabStrip;

    import org.androidannotations.annotations.AfterViews;
    import org.androidannotations.annotations.EActivity;
    import org.androidannotations.annotations.ViewById;

    import nl.*.android.DrawerActivity;
    import nl.*.android.home.HomeActivity_;
    import nl.*.android.R;
    import nl.*.android.utility.IFragmentSetter;
    import nl.*.android.utility.TabsPagerAdapter;

    @EActivity(R.layout.activity_orders)
    public class OrdersActivity extends DrawerActivity implements IFragmentSetter {

    @ViewById
    public ViewPager viewpager;
    @ViewById
    public PagerSlidingTabStrip strip;

    private TabsPagerAdapter adapter;

    @AfterViews
    public void init() {
        buildDrawer();
        adapter = new TabsPagerAdapter(getSupportFragmentManager(), this);
        addFragments();
        viewpager.setAdapter(adapter);
        strip.setViewPager(viewpager);
        if (getSupportActionBar() != null) {
            getSupportActionBar().setDisplayHomeAsUpEnabled(true);
            getSupportActionBar().setTitle("Bestellingen");
            getSupportActionBar().setHomeAsUpIndicator(R.drawable.ic_menu_white);
        }
    }

    private void addFragments() {
        adapter.addFragment(new OrdersNewFragment_(), "Nieuw");
        adapter.addFragment(new OrdersDeliveryFragment_(), "Afleveren");
        adapter.addFragment(new OrdersPickupFragment_(), "Ophalen");
    }

    @Override
    public void setFragment(Fragment fragment) {
        //geen implementatie nodig
    }

    @Override
    public void onBackPressed() {
        super.onBackPressed();
        final Intent i = HomeActivity_.intent(getApplicationContext()).get();
        i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        startActivity(i);
        finish();
    }
}

OrdersNewFragment.java [Tab 1]

package nl.*.android.order;

    import android.support.v4.app.Fragment;
    import android.widget.ListView;

    import org.androidannotations.annotations.AfterViews;
    import org.androidannotations.annotations.Background;
    import org.androidannotations.annotations.Bean;
    import org.androidannotations.annotations.EFragment;
    import org.androidannotations.annotations.UiThread;
    import org.androidannotations.annotations.ViewById;

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

    import nl.*.android.R;
    import nl.*.android.backend.API;
    import nl.*.android.backend.APIFactory;
    import nl.*.android.model.MOrderItem;
    import nl.*.android.model.MOrders;

    @EFragment(R.layout.fragment_orders_overview)
    public class OrdersNewFragment extends Fragment {

        @Bean
        public APIFactory apiFactory;

        private API api;

        private List<MOrderItem> items = new ArrayList<>();
        private OrderListAdapter adapter;

        @ViewById
        public ListView ordersList;

        @AfterViews
        public void init() {
            api = apiFactory.get();
            getNewOrders();
            adapter = new OrderListAdapter(getActivity(), R.id.ordersList, items);
            ordersList.setAdapter(adapter);
            dataChanged();
        }

        @UiThread
        public void dataChanged() {
            adapter.notifyDataSetChanged();
        }

        @Background
        public void getNewOrders() {
            items.clear();
            final MOrders result = api.getOrdersForNew();
            if (result != null) {
                Collections.addAll(items, result.result.orderList);
            }
        }

    }

OrdersDeliveryFragment.java [Tab 2]

package nl.*.android.order;

import android.support.v4.app.Fragment;
import android.widget.ListView;

import org.androidannotations.annotations.AfterViews;
import org.androidannotations.annotations.Background;
import org.androidannotations.annotations.Bean;
import org.androidannotations.annotations.EFragment;
import org.androidannotations.annotations.UiThread;
import org.androidannotations.annotations.ViewById;

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

import nl.*.android.R;
import nl.*.android.backend.API;
import nl.*.android.backend.APIFactory;
import nl.*.android.model.MOrderItem;
import nl.*.android.model.MOrders;

@EFragment(R.layout.fragment_orders_delivery)
public class OrdersDeliveryFragment extends Fragment {

    @Bean
    public APIFactory apiFactory;

    private API api;

    private List<MOrderItem> items = new ArrayList<>();
    private OrderListAdapter adapter;

    @ViewById
    public ListView ordersList;

    @AfterViews
    public void init() {
        api = apiFactory.get();
        getDeliveryOrders();
        adapter = new OrderListAdapter(getActivity(), R.id.ordersList, items);
        ordersList.setAdapter(adapter);
        dataChanged();
    }

    @UiThread
    public void dataChanged() {
        adapter.notifyDataSetChanged();
    }

    @Background
    public void getDeliveryOrders() {
        items.clear();
        final MOrders result = api.getOrdersForDelivery();
        if (result != null) {
            Collections.addAll(items, result.result.orderList);
        }
    }

}

OrdersPickupFragment.java [Tab 3]

package nl.*.android.order;

import android.support.v4.app.Fragment;
import android.widget.ListView;

import org.androidannotations.annotations.AfterViews;
import org.androidannotations.annotations.Background;
import org.androidannotations.annotations.Bean;
import org.androidannotations.annotations.EFragment;
import org.androidannotations.annotations.UiThread;
import org.androidannotations.annotations.ViewById;

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

import nl.*.android.R;
import nl.*.android.backend.API;
import nl.*.android.backend.APIFactory;
import nl.*.android.model.MOrderItem;
import nl.*.android.model.MOrders;

@EFragment(R.layout.fragment_orders_pickup)
public class OrdersPickupFragment extends Fragment {

    @Bean
    public APIFactory apiFactory;

    private API api;

    private List<MOrderItem> items = new ArrayList<>();
    private OrderListAdapter adapter;

    @ViewById
    public ListView ordersList;

    @AfterViews
    public void init() {
        api = apiFactory.get();
        getPickupOrders();
        adapter = new OrderListAdapter(getActivity(), R.id.ordersList, items);
        ordersList.setAdapter(adapter);
        dataChanged();
    }

    @UiThread
    public void dataChanged() {
        adapter.notifyDataSetChanged();
    }

    @Background
    public void getPickupOrders() {
        items.clear();
        final MOrders result = api.getOrdersForPickup();
        if (result != null) {
            Collections.addAll(items, result.result.orderList);
        }
    }

}

OrderListAdapter.java

package nl.****.android.order;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;

import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.List;
import java.util.Locale;

import nl.*.android.R;
import nl.*.android.model.MOrderItem;

/**
 * @author Niels
 * @version 1.0
 * @since 4-9-2015
 */
public class OrderListAdapter extends ArrayAdapter<MOrderItem> {

    private List<MOrderItem> itemList = new ArrayList<>();
    private Context context;
    private OrdersActivity activity;
    private static final SimpleDateFormat FORMATTER = new SimpleDateFormat("dd-MM-yyyy HH:mm", Locale.FRENCH);

    public OrderListAdapter(Context context, int resource, List<MOrderItem> orderList) {
        super(context, resource, orderList);
        this.itemList = orderList;
        this.context = context;
    }

    @Override
    public View getView(final int position, View view, ViewGroup parent) {
        view = LayoutInflater.from(getContext()).inflate(R.layout.list_single, parent, false);
        MOrderItem item = itemList.get(position);
        TextView label = (TextView) view.findViewById(R.id.txtKlant);
        TextView txt = (TextView) view.findViewById(R.id.txtDate);
        label.setText(item.name);
        txt.setText(FORMATTER.format(item.placeDate));
        return view;
    }

}

Thanks for any and all help.

Answer 1

Turns out I was notifying my listview that it's data set had changed before I actually finished getting the results.

Solution: move the line "dataChanged()" in the @AfterViews annotated method #init() to the @Background annotated method #getOrders().