android - 无论我做什么，我在 fragment 中的 recyclerview 都不会更新

Question

现在已经一周了，我真的很想找到解决方案，因为我需要在本周内向我的客户提交更新。因此，我在 fragment 中有一个 recyclerview，其中填充了使用 volley 库从 Web 服务获取的数据。如果将新数据添加到数据库中，我希望 recyclerview 重新加载/更新以实现更改或新添加的数据。现在，我尝试了很多方法，但未能实现我需要的。我尝试了以下方法:

-notifyDataSetChanged() 在我的适配器上，在处理程序内，在 onclick 内

-adapter.notifyItemRangeChanged(0, adapter.getItemCount());

-recyclerView.invalidate() 也在处理程序中- 分离和附加当前 fragment

-还尝试了以下代码。好吧，它之所以有效，是因为它刷新了整个 Activity 并返回到第一页的初始 fragment

Intent intent = getActivity().getIntent();
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_NEW_TASK
    | Intent.FLAG_ACTIVITY_NO_ANIMATION);
    getActivity().overridePendingTransition(0, 0);
    getActivity().finish();

    getActivity().overridePendingTransition(0, 0);
    startActivity(intent);

fragment 类

public class AddPlaylist extends Fragment {

RecyclerView recyclerView;
RecyclerAdapter adapter;
String[] id,title;
ArrayList<String> artist;
TextView text;

CreatePlaylist createPlaylist;

private CoordinatorLayout coordinatorLayout;
private FloatingActionButton fab;
 View view;

@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
     view = inflater.inflate(R.layout.addplaylist, container, false);

    coordinatorLayout = (CoordinatorLayout) view.findViewById(R.id
            .coordinatorLayout);

    fab = (FloatingActionButton) view.findViewById(R.id.fab);

    text = (TextView) view.findViewById(R.id.text);

    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            showInputDialog();
        }
    });

    id = getArguments().getStringArray("id");
    title = getArguments().getStringArray("title");

    artist = new ArrayList<String>(Arrays.asList(title));

    recyclerView= (RecyclerView) view.findViewById(R.id.my_recycler_view);
    adapter = new RecyclerAdapter("addplaylist", id, artist, getActivity());
    recyclerView.setAdapter(adapter);
    recyclerView.invalidate();
    recyclerView.setHasFixedSize(true);
    recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));

    adapter.notifyItemRangeChanged(0, adapter.getItemCount());

    final Handler mHandler = new Handler();

    mHandler.post(new Runnable() {

        @Override
        public void run() {

            adapter.notifyDataSetChanged();
            adapter.notifyItemRangeChanged(0, adapter.getItemCount());
            recyclerView.invalidate();

            Fragment frg = null;
            frg = getFragmentManager().findFragmentByTag("playlist");
            Bundle bundle = new Bundle();
            AddPlaylist addPlaylist = new AddPlaylist();
            bundle.putStringArray("id", JsonArray.ids);
            bundle.putStringArray("title", JsonArray.titles);
            addPlaylist.setArguments(bundle);
            final FragmentTransaction ft = getFragmentManager().beginTransaction();
            ft.detach(addPlaylist);
            ft.attach(addPlaylist);
            ft.commit();

        }
    });

    return view;
}

protected void showInputDialog() {

    // get prompts.xml view
    LayoutInflater layoutInflater = LayoutInflater.from(getActivity());
    View promptView = layoutInflater.inflate(R.layout.input_dialog, null);
    AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(getActivity());
    alertDialogBuilder.setView(promptView);

    final EditText editText = (EditText) promptView.findViewById(R.id.edittext);
    // setup a dialog window
    alertDialogBuilder.setCancelable(false)
            .setPositiveButton("OK", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int id) {
                    //text.setText("Hello, " + editText.getText());
                    createPlaylist.createPlaylist(editText.getText().toString());

                    /*Intent intent = getActivity().getIntent();
                    intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_NEW_TASK
                            | Intent.FLAG_ACTIVITY_NO_ANIMATION);
                    getActivity().overridePendingTransition(0, 0);
                    getActivity().finish();

                    getActivity().overridePendingTransition(0, 0);
                    startActivity(intent);*/
                    /*Bundle bundle = new Bundle();
                    Collections collections = new Collections();
                    AddPlaylist addPlaylist = new AddPlaylist();
                    bundle.putStringArray("id", JsonArray.ids);
                    bundle.putStringArray("title", JsonArray.titles);
                    bundle.putString("fragment", "addfragment");
                    addPlaylist.setArguments(bundle);
                    Fragment frg = null;
                    frg = getFragmentManager().findFragmentByTag("playlist");
                    final FragmentTransaction ft = getFragmentManager().beginTransaction();
                    ft.detach(collections);
                    ft.attach(frg);
                    ft.commit();*/



                    /*getActivity().runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            adapter.notifyDataSetChanged();
                        }
                    });*/

                    /*FragmentManager fragmentTransaction = getFragmentManager();
                    android.app.FragmentTransaction transaction = fragmentTransaction.beginTransaction();
                    Bundle bundle = new Bundle();
                    AddPlaylist addPlaylist = new AddPlaylist();
                    bundle.putStringArray("id", JsonArray.ids);
                    bundle.putStringArray("title", JsonArray.titles);
                    addPlaylist.setArguments(bundle);
                    transaction.addToBackStack("xyz");
                    transaction.add(R.id.containerView, addPlaylist);
                    //transaction.setTransition(FragmentTransaction.TRANSIT_ENTER_MASK);
                    transaction.commit();*/

                    adapter.notifyItemRangeChanged(0, adapter.getItemCount());
                }
            })
            .setNegativeButton("Cancel",
                    new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int id) {
                            dialog.cancel();
                        }
                    });

    // create an alert dialog
    AlertDialog alert = alertDialogBuilder.create();
    alert.show();
}

@UiThread
protected void dataSetChanged() {
    adapter.notifyDataSetChanged();
}

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);

    id = getArguments().getStringArray("id");
    title = getArguments().getStringArray("title");

    artist = new ArrayList<String>(Arrays.asList(title));

    adapter = new RecyclerAdapter("addplaylist", id, artist, getActivity());
    adapter.notifyDataSetChanged();
}

@Override
public void onAttach(Activity activity) {
    super.onAttach(activity);
    try{
        createPlaylist = (CreatePlaylist) activity;
    }catch(Exception e) {

    }
}

public interface CreatePlaylist{

     void createPlaylist(String name);

    }
}

对不起，乱七八糟的代码。这是我都尝试过的。

Answer 1

发生这种情况是因为您的适配器“丢失了”。首先，您创建适配器。那挺好的。然后你得到新的数据。您所做的是创建另一个适配器，并更改第二个适配器中的数据，该适配器未附加到您的 RecyclerView。

这不是最优雅的解决方案，但它会起作用。在 onActivityResult 中更改这些行:

 artist = new ArrayList<String>(Arrays.asList(title));

adapter = new RecyclerAdapter("addplaylist", id, artist, getActivity());

到

List<String> newArtist = new ArrayList<String>(Arrays.asList(title));
artist.clear();
artist.addAll(newArtist);
adapter.notifyDataSetChanged();

因为你的列表 artist 是对象，当你将它传递给你的 Recycler 适配器时，你更新相同的实例，相同的列表，所以你不需要创建新的适配器，因为适配器仍然有访问同一实例。把它想象成一桶水。您可以清空桶或装满桶，但桶保持不变。