Android Open Source - u2020-v2 Recycler View Fragment

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License

The source code is released under:

Apache License

Java Source Code

package com.gabor.recyclerview;
/*  www .j a va2 s.  c om*/
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import com.gabor.database.Car;
import com.gabor.database.CarT;
import com.gabor.database.DbHelper;
import com.google.gson.Gson;

import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.List;

import rx.Observable;
import rx.Subscriber;
import rx.Subscription;
import rx.functions.Action1;
import rx.schedulers.Schedulers;
import rx.subscriptions.Subscriptions;

import static rx.android.app.AppObservable.bindFragment;

/**
 * Problem:
 * You have a data source (where that data is potentially expensive to obtain), and you want to
 * emit this data into a fragment. However, you want to gracefully deal with rotation changes and
 * not lose any data already emitted.
 * <p/>
 * Solution:
 * Combine {@link android.app.Fragment#setRetainInstance(boolean)} with
 * {@link rx.android.schedulers.AndroidSchedulers#mainThread()} and {@link rx.Observable#cache()}
 */
public class RecyclerViewFragment extends Fragment {

    private Observable<Car> observables;
    private Subscription subscription = Subscriptions.empty();
    private static int density;
    private static final String TAG = "RecyclerViewFragment";

    public RecyclerViewFragment() { setRetainInstance(true); }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        density = getActivity().getResources().getDisplayMetrics().densityDpi;

        InputStream is = null;
        try {
            is = getActivity().getAssets().open("car_list.json");
        } catch (Exception e) {
            Log.i(TAG, e.getMessage());
        }
        if (is != null)
            observables = bindFragment(this, fakeApiCall(is).cache());
        // in retained fragments, it's sufficient to bind the fragment in onCreate, since
        // Android takes care of detaching the Activity for us, and holding a reference for
        // the duration of the observable does not harm.
    }

    @Override
    public void onDestroyView() {
        subscription.unsubscribe();
        super.onDestroyView();
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        getActivity().setProgressBarIndeterminateVisibility(true);
        return inflater.inflate(R.layout.recycler_view_frag, container, false);
    }

    @Override
    public void onViewCreated(final View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        final RecyclerView recyclerView = (RecyclerView) view.findViewById(R.id.recyclerView);
        recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));

        // (re-)subscribe to the sequence, which either emits the cached result or simply re-
        // attaches the subscriber to wait for it to arrive
        subscription = observables.subscribe(new Action1<Car>() {
            @Override
            public void call(Car result) {
                recyclerView.setAdapter(new CustomAdapter(result, density));
                getActivity().setProgressBarIndeterminateVisibility(false);
            }
        });
    }
    
    // this would go to a networking class in a production app
    public static Observable<Car> fakeApiCall(final InputStream is) {
        return Observable.create(new Observable.OnSubscribe<Car>() {
            @Override
            public void call(Subscriber<? super Car> subscriber) {
                List<CarT> cars = DbHelper.getCars();
                Car car;
                if (cars.size() != 0) 
                    car = DbHelper.toCar(cars);
                else {
                    car = new Gson().fromJson(new InputStreamReader(is), Car.class);
                    DbHelper.save(car);
                }
                subscriber.onNext(car);
                subscriber.onCompleted();
            }
        }).subscribeOn(Schedulers.io());
    }
}

Java Source Code List

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