我的fragment中的RecyclerView无论我怎么做都没有更新。

Question

现在已经过去一周了，我非常需要一个解决方案，因为我需要在本周向我的客户呈现更新。所以，我有一个位于片段内的recyclerview，其中填充了使用volley库从网络服务中获取的数据。如果数据库中添加了新数据，我希望recyclerview重新加载/更新以实现更改或新添加的内容。现在，我尝试了许多方法，但未能实现所需的内容。我尝试了以下方法：

- 在处理程序内部，单击notifyDataSetChanged()适配器 - adapter.notifyItemRangeChanged(0, adapter.getItemCount()); - recyclerView.invalidate()也在处理程序内 - 分离和附加当前片段

另外，我还尝试了下面的代码。好吧，它可以工作，因为它会刷新整个活动并返回到最初的片段，即第一页。

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);

片段类

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);

    }
}

抱歉代码很乱。这是我尝试的全部内容。

- Renboy

Answer 1

这种情况发生是因为你的适配器“丢失”了。首先，你创建了适配器，这是很好的。然后你获取新数据。你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，但该适配器未连接到你的RecyclerView。

这不是最优雅的解决方案，但它可以工作。在onActivityResult中更改以下行：

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

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

为了

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

当你的列表 artist 是对象时，当你将它传递给你的 Recycler 适配器，并更新同一实例、同一列表时，你不需要创建新的适配器，因为适配器仍然可以访问同一实例。把它想象成一个水桶。你可以倒空水桶，或者加满水，但是水桶始终是同一个。

- Marius Kaunietis

---

你的意思是删除那两行并用那四行替换吗？因为我得到了一些空指针。 - Renboy

recyclerView = (RecyclerView) view.findViewById(R.id.my_recycler_view); ArrayList<String> newArtist = new ArrayList<String>(Arrays.asList(title)); adapter = new RecyclerAdapter("addplaylist", id, newArtist, getActivity()); artist.clear(); artist.addAll(newArtist); adapter.notifyDataSetChanged(); recyclerView.setAdapter(adapter); recyclerView.invalidate(); recyclerView.setHasFixedSize(true); recyclerView.setLayoutManager(new LinearLayoutManager(getActivity())); - Renboy

抱歉，我表达不够清晰。我已经更新了我的答案。 - Marius Kaunietis

所以你的问题不在于RecyclerView/adapter，而在于更新你的数据。 - Marius Kaunietis

所以，我现在唯一的解决方案是完全重新加载该活动，因为这是我唯一有效的方法。不过，我可以问一下吗？重新加载活动后，您能否将初始片段替换为当前所在的片段？ - Renboy