此回调中的 getLoaderManager().initLoader 错误

Question

第一次使用Loader。调用方法后

getLoaderManager().initLoader(0, null, this); 我在参数“this”中遇到错误。

编译后出错：

error: method initLoader in class LoaderManager cannot be applied to given types; getLoaderManager().initLoader(0, null, this); ^ required: int,Bundle,LoaderCallbacks found: int,,MainActivity reason: cannot infer type-variable(s) D (argument mismatch; MainActivity cannot be converted to LoaderCallbacks) where D is a type-variable: D extends Object declared in method initLoader(int,Bundle,LoaderCallbacks)

我的代码：

package com.example.newsapp;

import android.content.Context;
import android.content.Intent;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.net.Uri;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.loader.app.LoaderManager;
import androidx.loader.content.Loader;
import java.util.ArrayList;
import java.util.List;




public class MainActivity extends AppCompatActivity implements LoaderManager.LoaderCallbacks<List<News>> {

private static final String URL = "http://content.guardianapis.com/search";
private NewsAdapter newsAdapter;
private TextView emptyListStateTextView;
private Intent intent;
ListView newsListView;

@Override
protected void onCreate(Bundle savedInstanceState) {
    Log.e("MainActivity", "RUN onCreate...");
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    newsListView = findViewById(R.id.listView);
    emptyListStateTextView = findViewById(R.id.defautView);
    newsListView.setEmptyView(emptyListStateTextView);

    newsAdapter = new NewsAdapter(this, new ArrayList<News>());
    newsListView.setAdapter(newsAdapter);

    newsListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

            News currentNews = newsAdapter.getItem(position);

            Uri uri = Uri.parse(currentNews.getUrl());

            intent= new Intent(Intent.ACTION_VIEW, uri);

            startActivity(intent);
        }
    });

    ConnectivityManager connMgr = (ConnectivityManager)
            getSystemService(Context.CONNECTIVITY_SERVICE);

    NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();

    if (networkInfo == null) {
        View loadingIndicator = findViewById(R.id.loading_bar);
        loadingIndicator.setVisibility(View.GONE);

        emptyListStateTextView.setText("No internet connection");
    }else{

        getLoaderManager().initLoader(0, null, this);
    }
    Log.e("MainActivity", "DONE onCreate...");
}

@NonNull
@Override
public Loader<List<News>> onCreateLoader(int i, Bundle args) {
    Log.e("MainActivity", "RUN onCreateLoader...");

    //TEST
    Uri baseUri = Uri.parse(URL);
    Uri.Builder uriBuilder = baseUri.buildUpon();

    uriBuilder.appendQueryParameter("show-tags", "contributor");
    uriBuilder.appendQueryParameter("section", "technology");
    uriBuilder.appendQueryParameter("order-by", "newest");
    uriBuilder.appendQueryParameter("from-date", "2018-01-01");
    uriBuilder.appendQueryParameter("api-key", "test");

    Log.v("my_tag", "url created is: "+uriBuilder.toString());
    //TEST
    Log.e("MainActivity", "DONE onCreateLoader...");
    return new NewsLoader(this, uriBuilder.toString());
}

@Override
public void onLoadFinished(@NonNull Loader<List<News>> loader, List<News> data) {
    Log.e("MainActivity", "RUN onLoadFinished...");
    View loadingBar = findViewById(R.id.loading_bar);
    loadingBar.setVisibility(View.GONE);

    newsAdapter.clear();

    if(data != null && !data.isEmpty()){
        newsAdapter.addAll(data);
    }
    Log.e("MainActivity", "DONE onLoadFinished...");
}

@Override
public void onLoaderReset(@NonNull Loader<List<News>> loader) {
    Log.e("MainActivity", "RUN onLoaderReset...");
    newsAdapter.clear();
    Log.e("MainActivity", "DONE onLoaderReset...");
   }
}

我个人认为，问题一定出在导入的某个地方。即使我真的很感激任何帮助。

谢谢！

Answer 1

getLoaderManager 已贬值，请使用 getSupportLoaderManager 代替：

getSupportLoaderManager().initLoader(0, null, this);

但是，如果您仍然想使用它，那是因为导入不正确。导入加载程序回调，它应该可以解决问题

android.app.LoaderCallbacks

此回调中的 getLoaderManager().initLoader 错误

getLoaderManager().initLoader error in this callback

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