TweetsService.java

import android.content.Context;

import com.google.gson.GsonBuilder;
import com.maketrumptweetseightagain.R;
import com.twitter.sdk.android.core.models.Tweet;

import java.util.List;

import javax.inject.Inject;

import io.reactivex.Single;
import okhttp3.OkHttpClient;
import retrofit2.Retrofit;
import retrofit2.adapter.rxjava2.RxJava2CallAdapterFactory;
import retrofit2.converter.gson.GsonConverterFactory;

public class TweetsService {

    private static final String SCREEN_NAME = "realDonaldTrump";
    private static final String TWEET_MODE = "extended";
    private static final boolean TRIM_USER = true;

    private static final int COUNT = 150;

    private TweetsApi tweetsApi;

    @Inject
    public TweetsService(Context context) {
        Retrofit retrofit = new Retrofit.Builder().baseUrl(context.getString(R.string.tweets_base_url))
                .addCallAdapterFactory(RxJava2CallAdapterFactory())
                .addConverterFactory(gsonConverterFactory())
                .client(client(context))
                .build();
        tweetsApi = retrofit.create(TweetsApi.class);
    }

    private RxJava2CallAdapterFactory RxJava2CallAdapterFactory() {
        return RxJava2CallAdapterFactory.create();
    }

    private GsonConverterFactory gsonConverterFactory() {
        return GsonConverterFactory.create(new GsonBuilder().create());
    }

    private OkHttpClient client(Context context) {
        OkHttpClient.Builder builder = new OkHttpClient.Builder();
        builder.addNetworkInterceptor(interceptor(context));
        return builder.build();
    }

    private Oauth1SigningInterceptor interceptor(Context context) {
        return new Oauth1SigningInterceptor.Builder()
                .accessToken(context.getString(R.string.token))
                .accessSecret(context.getString(R.string.token_secret))
                .consumerKey(context.getString(R.string.consumer_key))
                .consumerSecret(context.getString(R.string.consumer_secret))
                .clock(new Oauth1SigningInterceptor.Clock())
                .build();
    }

    public Single<List<Tweet>> getTweets(int page) {
        return tweetsApi.getTweets(SCREEN_NAME, TRIM_USER, TWEET_MODE, COUNT, page);
    }
}