Coinfo

info about coins

A basic project implementation of Chasing Coins API with implemented Android Architecture Components.

Basic Implementation of ViewModels + LiveData

1. Create your ViewModel class composed of a getData() method and a MutableLiveData of your model:

public class CoinsListViewModel extends BaseViewModel {

    private MutableLiveData<List<String>> coinsList;

    public LiveData<List<String>> getCoinsList() {
        if (coinsList == null) {
            coinsList = new MutableLiveData<>();
            fetchData();
        }

        return coinsList;
    }

    public void fetchData() {
        disposable.add(apiClient.fetchCoinsList()
                .subscribeOn(Schedulers.newThread())
                .unsubscribeOn(Schedulers.newThread())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribeWith(new DisposableObserver<List<String>>() {
                    @Override
                    public void onNext(List<String> value) {
                        coinsList.postValue(value);
                    }

                    @Override
                    public void onError(Throwable e) {
                        coinsList.postValue(new ArrayList<String>());
                    }

                    @Override
                    public void onComplete() {
                    }
                }));
    }
}

2. Implement it in your Activity or Fragment by retrieving the ViewModel’s instance from the ViewModelsProvider and to be used for the current scope (until Activity/Fragment is destroyed completely).

    private CoinsListViewModel coinsListViewModel;

3. Upon the creation of your Activity/Fragment (onCreate method), initialize the ViewModel, optionally you can assign an Observer for the ViewModel to detect changes and update the views with the changes in the data.

    coinsListViewModel = ViewModelProviders.of(this).get(CoinsListViewModel.class);
    coinsListViewModel.getCoinsList().observeForever(coinsListObserver);

4. The observer used is this:

    private Observer<List<String>> coinsListObserver = new Observer<List<String>>() {
        @Override
        public void onChanged(@Nullable List<String> strings) {
            coinsList.addAll(strings);
            coinsListAdapter.notifyDataSetChanged();
        }
    };

Whenever there are changes in the data for the list of coins, the RecyclerView adapter will be updated and the list will also be updated.

The API client uses Retrofit 2 for API calls