Caching data in RAM

RestaurantDetailsRepository

import android.util.LruCache;

import androidx.annotation.MainThread;
import androidx.annotation.NonNull;
import androidx.lifecycle.LiveData;
import androidx.lifecycle.MutableLiveData;

import fr.delcey.go4lunch.data.restaurant_details.pojo.RestaurantDetailsResponse;
import fr.delcey.go4lunch.data.restaurant_details.pojo.RestaurantDetailsResponseWrapper;
import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Response;

/**
 * This Repository is very important to avoid giving $$$ to Google because we made too many requests to the Places (Detail) API.
 * It caches the RestaurantDetails in a LruCache to avoid querying too much data online.
 */
public class RestaurantDetailsRepository {

    @NonNull
    private final RestaurantDetailsApi restaurantDetailsApi;

    private final LruCache<String, RestaurantDetailsResponse> cache = new LruCache<>(2_000);

    public RestaurantDetailsRepository(@NonNull RestaurantDetailsApi restaurantDetailsApi) {
        this.restaurantDetailsApi = restaurantDetailsApi;
    }

    @MainThread
    @NonNull
    public LiveData<RestaurantDetailsResponse> getRestaurantDetailsLiveData(@NonNull String placeId) {
        MutableLiveData<RestaurantDetailsResponse> restaurantDetailsResponseMutableLiveData = new MutableLiveData<>();

        // 1. We search in our cache with the placeId
        RestaurantDetailsResponse existing = cache.get(placeId);
        if (existing != null) {
            // 2a. We found a similar query already existing, great ! No need to waste resources with an API call on Google's servers
            restaurantDetailsResponseMutableLiveData.setValue(existing);
        } else {
            // 2b. Nothing similar in cache, query Google !
            restaurantDetailsApi.getRestaurantDetails(placeId).enqueue(new Callback<RestaurantDetailsResponseWrapper>() {
                @Override
                public void onResponse(
                    @NonNull Call<RestaurantDetailsResponseWrapper> call,
                    @NonNull Response<RestaurantDetailsResponseWrapper> response
                ) {
                    RestaurantDetailsResponseWrapper body = response.body();

                    if (body != null) {
                        // 3. Save the result for next time...
                        cache.put(placeId, body.getRestaurantDetailsResponse());

                        restaurantDetailsResponseMutableLiveData.setValue(body.getRestaurantDetailsResponse());
                    }
                }

                @Override
                public void onFailure(@NonNull Call<RestaurantDetailsResponseWrapper> call, @NonNull Throwable t) {
                    t.printStackTrace();
                }
            });
        }

        return restaurantDetailsResponseMutableLiveData;
    }