Loaders: метод onCreateLoader (), вызываемый ранее (Loader Manager) .initLoader () - PullRequest
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Loaders: метод onCreateLoader (), вызываемый ранее (Loader Manager) .initLoader ()

0 голосов
/ 02 апреля 2020

Я пытаюсь реализовать простой Loader, и это мой код 

public class EarthquakeActivity extends AppCompatActivity implements LoaderManager.LoaderCallbacks<List<Quake>> {

    /**
     * Constant value for the earthquake loader ID. We can choose any integer.
     * This really only comes into play if you're using multiple loaders.
     */
    private static final int EARTHQUAKE_LOADER_ID = 1;

    /** URL for earthquake data from the USGS dataset */
    private static final String USGS_REQUEST_URL =
            "https://earthquake.usgs.gov/fdsnws/event/1/query?format=geojson&eventtype=earthquake&orderby=time&minmag=6&limit=10";

    public static final String TAG = EarthquakeActivity.class.getName();

    //Made it global as it needs to be accessed by other class too
    private QuakeAdapter mAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        Log.e(TAG,"OnCreate()");
        super.onCreate(savedInstanceState);
        setContentView(R.layout.earthquake_activity);

        // Find a reference to the {@link ListView} in the layout
        ListView earthquakeListView = (ListView) findViewById(R.id.list);

        // Create a new adapter that takes an empty list of earthquakes as input
        mAdapter = new QuakeAdapter(this, new ArrayList<Quake>());

        // Set the adapter on the {@link ListView}
        // so the list can be populated in the user interface
        earthquakeListView.setAdapter(mAdapter);


        // Get a reference to the LoaderManager, in order to interact with loaders.
        LoaderManager loaderManager = getSupportLoaderManager();
        // Initialize the loader. Pass in the int ID constant defined above and pass in null for
        // the bundle. Pass in this activity for the LoaderCallbacks parameter (which is valid
        // because this activity implements the LoaderCallbacks interface).
        loaderManager.initLoader(EARTHQUAKE_LOADER_ID, null, this);
        Log.e(TAG,"loaderManager.initLoader()");


        // Set an item click listener on the ListView, which sends an intent to a web browser
        // to open a website with more information about the selected earthquake.
        earthquakeListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int position, long l) {
                // Find the current earthquake that was clicked on
                Quake currentEarthquake = mAdapter.getItem(position);

                // Convert the String URL into a URI object (to pass into the Intent constructor)
                Uri earthquakeUri = Uri.parse(currentEarthquake.getLink());

                // Create a new intent to view the earthquake URI
                Intent websiteIntent = new Intent(Intent.ACTION_VIEW, earthquakeUri);

                // Send the intent to launch a new activity
                startActivity(websiteIntent);
            }
        });


    }

    @NonNull
    @Override
    public Loader<List<Quake>> onCreateLoader(int i, Bundle bundle) {
        // Create a new loader for the given URL
        Log.e(TAG,"OnCreateLoader");
        return new EarthquakeLoader(this, USGS_REQUEST_URL);
    }

    @Override
    public void onLoadFinished(Loader<List<Quake>> loader, List<Quake> earthquakes) {
        // Clear the adapter of previous earthquake data
        mAdapter.clear();

        // If there is a valid list of {@link Earthquake}s, then add them to the adapter's
        // data set. This will trigger the ListView to update.
        if (earthquakes != null && !earthquakes.isEmpty()) {
            mAdapter.addAll(earthquakes);
            mAdapter.notifyDataSetChanged();
            Log.e(TAG,"OnLoadFinished");
        }
    }
    @Override
    public void onLoaderReset(@NonNull Loader<List<Quake>> loader) {
        // Loader reset, so we can clear out our existing data.
        mAdapter.clear();
        Log.e(TAG,"OnLoaderReset");
    }


}

Все это прекрасно работает, но сообщения журнала, особенно их порядок, меня смущает. Вот они: 

2020-04-02 17:48:26.989 3716-3716/com.example.android.quakereport E/com.example.android.quakereport.EarthquakeActivity: OnCreate()
2020-04-02 17:48:27.249 3716-3716/com.example.android.quakereport E/com.example.android.quakereport.EarthquakeActivity: OnCreateLoader
2020-04-02 17:48:27.255 3716-3716/com.example.android.quakereport E/com.example.android.quakereport.EarthquakeActivity: loaderManager.initLoader()
2020-04-02 17:48:27.272 3716-3716/com.example.android.quakereport E/com.example.android.quakereport.EarthquakeLoader: OnStartLoading()
2020-04-02 17:48:27.276 3716-3738/com.example.android.quakereport E/com.example.android.quakereport.EarthquakeLoader: loadInBackground
2020-04-02 17:48:29.698 3716-3738/com.example.android.quakereport E/com.example.android.quakereport.EarthquakeLoader: loadInBackground:fetchEarthquakeData()
2020-04-02 17:48:29.702 3716-3716/com.example.android.quakereport E/com.example.android.quakereport.EarthquakeActivity: OnLoadFinished

Разве метод initLoader () менеджера загрузчиков не должен проверять существующий загрузчик перед вызовом метода onCreateLoader ()? Отчеты журнала, казалось, предполагали, что это происходит в другом порядке, и я не понимаю, почему это происходит. Буду очень признателен за любые идеи, так как я начинающий

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