下面是earthquakeactivity.java

package android.example.quakereports;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.loader.app.LoaderManager;
import androidx.loader.content.Loader;

import android.content.Intent;

import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;

import java.util.ArrayList;
import java.util.List;

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

    private quakeAdapter mAdapter;

    /**
     * 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&orderby=time&minmag=5&limit=10";
    private static final int EARTHQUAKE_LOADER_ID = 1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ListView earthquakeListView = (ListView) findViewById(R.id.list);
        mAdapter = new quakeAdapter(this, new ArrayList<Earthquake>());
        earthquakeListView.setAdapter(mAdapter);
        LoaderManager loaderManager=getLoaderManager();//         gives error here
        loaderManager.initLoader(EARTHQUAKE_LOADER_ID,null,this);
        earthquakeListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int position, long id) {
                Earthquake currentquake = (Earthquake) mAdapter.getItem(position);
                Uri earthQuakeUri = Uri.parse(currentquake.getUrl());
                Intent i = new Intent(Intent.ACTION_VIEW, earthQuakeUri);
                startActivity(i);
            }
        });
    }
    @NonNull
    @Override
    public Loader<List<Earthquake>> onCreateLoader(int id, Bundle args) {
        return new myAsyncTaskLoader(this,USGS_REQUEST_URL);
    }

    @Override
    public void onLoadFinished(Loader<List<Earthquake>> loader, List<Earthquake> data) {
        // 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 (data != null && !data.isEmpty()) {
            mAdapter.addAll(data);
        }
    }

    @Override
    public void onLoaderReset(Loader<List<Earthquake>> loader) {
        mAdapter.clear();
    }
}

这里是masynctaskloader.java

package android.example.quakereports;

import android.content.Context;

import androidx.loader.content.AsyncTaskLoader;

import java.util.List;

public class myAsyncTaskLoader extends AsyncTaskLoader<List<Earthquake>> {

    private String mUrl=null;

    @Override
    protected void onStartLoading() {
        forceLoad();
    }

    @Override
    public List<Earthquake> loadInBackground() {
        if(mUrl==null)
        {
            return null;
        }
        return QueryUtils.fetchEarthquakeData(mUrl);
    }

    public myAsyncTaskLoader(Context context, String url)
    {
        super(context);
        mUrl=url;
    }
}

myasynctaskloader.java文件没有问题，它工作正常。在asynctaskloader和loadermanager涉及的任何地方，我都使用过androidx库。我已经在我面临错误的那一行上发表了评论。有没有什么方法可以在没有任何错误的情况下初始化我的加载程序，或者我应该使用 import android.app.LoaderManager.LoaderCallbacks; 像android支持库一样，这是唯一的选择吗？