无法将片段转换为 rss reader 中的 android.app.Activity

Question

我按照 this 教程创建了一个 rss reader（不幸的是，它是西班牙语）。但是，由于我的 rss 必须在片段中，我将 MainActivity 转换为片段：

import android.content.Context;
import android.content.Intent;
import android.database.Cursor;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.widget.SimpleCursorAdapter;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ListView;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.my.app.MainActivity_tabs;
import com.my.app.Modelo.FeedDatabase;
import com.my.app.Modelo.ScriptDatabase;
import com.my.app.R;
import com.my.app.RssParse.Rss;
import com.my.app.Web.VolleySingleton;
import com.my.app.Web.XmlRequest;

/**
 * Creado por Hermosa Programación
 *
 * Actividad principal que representa el Home de la aplicación
 */

public class News extends Fragment {


private static final String TAG = MainActivity_tabs.class.getSimpleName();

public static final String URL_FEED = "www.forbes.com/fdc/rss.html";

private ListView listView;

private FeedAdapter adapter;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {

    View rootView = inflater.inflate(R.layout.activity_tab2, container, false);


    // Obtener la lista
    listView = (ListView) getActivity().findViewById(R.id.lista);

    ConnectivityManager connMgr = (ConnectivityManager)
            getActivity().getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();
    if (networkInfo != null && networkInfo.isConnected()) {
        VolleySingleton.getInstance(getActivity()).addToRequestQueue(
                new XmlRequest<>(
                        URL_FEED,
                        Rss.class,
                        null,
                        new Response.Listener<Rss>() {
                            @Override
                            public void onResponse(Rss response) {
                                // Caching
                                FeedDatabase.getInstance(getActivity()).
                                        sincronizarEntradas(response.getChannel().getItems());
                                // Carga inicial de datos...
                                new LoadData().execute();
                            }
                        },
                        new Response.ErrorListener() {
                            @Override
                            public void onErrorResponse(VolleyError error) {
                                Log.d(TAG, "Error Volley: " + error.getMessage());
                            }
                        }
                )
        );
    } else {
        Log.i(TAG, "La conexión a internet no está disponible");
        adapter = new FeedAdapter(
                getActivity(),
                FeedDatabase.getInstance(getActivity()).obtenerEntradas(),
                SimpleCursorAdapter.FLAG_REGISTER_CONTENT_OBSERVER);
        listView.setAdapter(adapter);
    }


    // Regisgrar escucha de la lista
    listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            Cursor c = (Cursor) adapter.getItem(position);

            // Obtene url de la entrada seleccionada
            String url = c.getString(c.getColumnIndex(ScriptDatabase.ColumnEntradas.URL));

            // Nuevo intent explícito
            Intent i = new Intent(getActivity(), DetailActivity.class);

            // Setear url
            i.putExtra("url-extra", url);

            // Iniciar actividad
            startActivity(i);
        }
    });

    return rootView;
}

public class LoadData extends AsyncTask<Void, Void, Cursor> {

    @Override
    protected Cursor doInBackground(Void... params) {
        // Carga inicial de registros
        return FeedDatabase.getInstance(getActivity()).obtenerEntradas();

    }

    @Override
    protected void onPostExecute(Cursor cursor) {
        super.onPostExecute(cursor);

        // Crear el adaptador
        adapter = new FeedAdapter(
                getActivity(),
                cursor,
                SimpleCursorAdapter.FLAG_REGISTER_CONTENT_OBSERVER);

        // Relacionar la lista con el adaptador
        listView.setAdapter(adapter);
    }
}

}

但是当我运行应用程序时，出现以下错误，我无法弄清楚为什么会发生这种情况，有什么想法吗？

java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.my.app/com.my.app.UI.News}: java.lang.ClassCastException: com.my.app.UI.News cannot be cast to android.app.Activity
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2319)
        at android.app.ActivityThread.access00(ActivityThread.java:135)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1232)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:136)
        at android.app.ActivityThread.main(ActivityThread.java:5253)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:515)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:939)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
        at dalvik.system.NativeStart.main(Native Method)
 Caused by: java.lang.ClassCastException: com.my.app.UI.News cannot be  cast to android.app.Activity
            at android.app.Instrumentation.newActivity(Instrumentation.java:1064)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2186)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2319)
            at android.app.ActivityThread.access00(ActivityThread.java:135)
            at 
android.app.ActivityThread$H.handleMessage(ActivityThread.java:1232)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5253)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:939)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
            at dalvik.system.NativeStart.main(Native Method)

Answer 1

您之前启动 News 的意图是一个 activity 现在正试图启动 News 这是一个片段（可能是因为清单中有 News 作为您的默认启动器 Activity）。您的片段需要保存在 activity 中。

请参阅教程 here，了解如何将片段添加到 activity。

无法将片段转换为 rss reader 中的 android.app.Activity

Fragment cannot be cast to android.app.Activity in rss reader

android

fragment

rss-reader

android-adapter