Progressbar 快速从 endlessrecycleview 中移除

Question

基本上我在我的项目中使用 MVP 和 RxJava，但是由于缺少 Youtube 的 Rx 版本API 我没有使用我的 MVP 方法。

目前我正在尝试制作 endlessrecycleview 的经典实现（使用 thread 的 ）来显示 youtube 视频。

我当前方法的问题是我无法弄清楚为什么 ProgressBar 很快被 endlessrecyleview 隐藏了。

private void setupRecyclerView() {
    mYoutubeVideoRecyclerView.setAdapter(adapter);
    mYoutubeVideoRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
    mYoutubeVideoRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
      @Override public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
        super.onScrolled(recyclerView, dx, dy);
        if (true && !(hasFooter())) {
          LinearLayoutManager layoutManager = (LinearLayoutManager) recyclerView.getLayoutManager();
          //position starts at 0
          if (layoutManager.findLastCompletelyVisibleItemPosition()
              == layoutManager.getItemCount() - 2) {
            Log.d(TAG, "ProgressBar - item INSERTED At index = " + adapter.getItemCount());
            adapter.getVideos().add(null);
            recyclerView.getAdapter().notifyItemInserted(adapter.getItemCount() - 1);

            // TODO: 9/20/16  the bellow 2 lines make the progressbar not being displayed
            getYoutubeVideos();
            displayDataOrShowMessage();
          }
        }
      }
    });
  }

...

private void getYoutubeVideos() {
    Thread thread = new Thread(new Runnable() {
      @Override public void run() {
        try {
          videoEntries = videoPresenter.getYoutubeVideoList(getActivity());
        } catch (Exception e) {
          e.printStackTrace();
        }
      }
    });
    thread.start();
    try {
      thread.join();
    } catch (InterruptedException e) {
      e.printStackTrace();
    }
  }

...

private void displayDataOrShowMessage() {
    if (videoEntries != null) {
      showVideos(videoEntries);
      showSelectedVideo((videoEntries.get(0)).getVideoId());
    } else {
      showMessage(R.string.probleme_connection);
      ((VideoPlayerFragment) (getActivity()).getFragmentManager().findFragmentByTag("video_player"))
          .pause();
    }
  }

...

public void showVideos(List<VideoEntry> videos) {
    Log.d(TAG, "ProgressBar - Adapter data size before adding items = " + adapter.getItemCount());
    try {
      int size = adapter.getItemCount();
      Log.d(TAG, "ProgressBar - item REMOVED from index = " + adapter.getItemCount());
      adapter.getVideos().remove(size - 1);//removes footer
      adapter.addVideos(videos);
      adapter.notifyItemRangeChanged(size - 1, adapter.getItemCount() - size);
    } catch (ArrayIndexOutOfBoundsException e) {
      adapter.addVideos(videos);
      adapter.notifyDataSetChanged();
    }
    Log.d(TAG, "ProgressBar - Adapter data size after adding items = " + adapter.getItemCount());

    mYoutubeVideoRecyclerView.requestFocus();
    progressBar.setVisibility(View.INVISIBLE);
    infoTextView.setVisibility(View.INVISIBLE);
    mYoutubeVideoRecyclerView.setVisibility(View.VISIBLE);
    Log.d(TAG, "showVideos -- data is set to list");
  }

Answer 1

它不起作用，因为您启动了一个新线程并使 UI 线程在您调用 join().

时等待它完成

您实际上是在阻塞 UI 线程，因此 adapter.getVideos().add(null); 和 adapter.getVideos().remove(size - 1); 会一个接一个地被立即调用，并且永远无法在屏幕上正确绘制。

你要做的是让那个线程运行空闲，不要 join() 它并将 videos 传回 UI 线程然后添加他们到适配器。当然，说起来容易做起来难。

一种 "easy" 方法是使用 AsyncTask (https://developer.android.com/reference/android/os/AsyncTask.html)，但如果您不知道自己的内存是什么，它们也有自己的潜在内存泄漏问题正在做。

正确的方法是让来自适配器的数据成为一个可以subscribed/unsusbribed的东西，然后让后台线程添加数据。但这是一个更大的重构，而不是答案的范围。

我知道这不是一个完整的答案，但我希望它能为您指明方向。

此外，我建议使用这个库 https://github.com/eyeem/RecyclerViewTools（我创建的）。它完全支持开箱即用的 heades/footers 和 EndlessScroll，应该可以使您的一些代码更容易。

Answer 2

好吧，异步是地狱所以我做了一个代码重构来使用 Rx 版本：

public void getYoutubeVideoList(final Context context, Boolean isRefresh) {
    MalitelApplication application = MalitelApplication.get(videoMvpView.getContext());
    MalitelService malitelService = application.getMalitelService(Constants.malitelYoutubeUrl);
    subscription = application.getYoutubeConnector().getYoutubeVideosObservable(isRefresh)
        .observeOn(AndroidSchedulers.mainThread())
        .subscribeOn(application.defaultSubscribeScheduler())
        .subscribe(new Observer<List<VideoEntry>>() {
          @Override public void onCompleted() {
          }

          @Override public void onError(Throwable e) {
            videoMvpView.showMessage(R.string.probleme_connection);
          }

          @Override public void onNext(List<VideoEntry> videos) {
            videoMvpView.showVideos(videos);
            videoMvpView.showSelectedVideo((videos.get(0)).getText());
          }
        });
  }

..

public Observable<List<VideoEntry>> getYoutubeVideosObservable(final Boolean isRefresh) {
    return Observable.create(new Observable.OnSubscribe<List<VideoEntry>>() {
      @Override public void call(Subscriber<? super List<VideoEntry>> subscriber) {
        try {
          search =
              youtube.search().list("id,snippet").setChannelId(Constants.malitelYoutubeChannelId);
          search.setKey(DeveloperKey.DEVELOPER_KEY);
          search.setType("video");
          search.setMaxResults(NUMBER_OF_VIDEOS_RETURNED);
          search.setFields(
              "items(id/videoId,snippet/title,snippet/description,snippet/thumbnails/default/url),"
                  + "nextPageToken,pageInfo,prevPageToken");

          if (!isRefresh) {
            search.setPageToken(nextPageToken);
          } else {
            totalResults = 0;
          }
        } catch (IOException e) {
          Log.d(TAG, "Could not initialize: " + e);
        }

        // Call the API and print results.
        SearchListResponse searchResponse = null;
        List<SearchResult> searchResultList = null;
        try {
          searchResponse = search.execute();

          if (searchResponse != null) {
            searchResultList = searchResponse.getItems();
            nextPageToken = searchResponse.getNextPageToken();
            if (nextPageToken != null) Log.d(TAG, nextPageToken);
          }

          if (searchResultList != null) {
            fillVideoEntry(searchResultList.iterator());
          }

          if (mVideoEntries != null) {
            totalResults += mVideoEntries.size();
            Log.d(TAG, "totalResults : " + totalResults);
          }

          if (!subscriber.isUnsubscribed()) {
            subscriber.onNext(mVideoEntries);
            subscriber.onCompleted();
          }
        } catch (IOException e) {
          if (!subscriber.isUnsubscribed()) {
            subscriber.onError(e);
          }
        }
      }
    });
  }

Progressbar 快速从 endlessrecycleview 中移除

Progressbar quickly removed from endlessrecycleview

android

youtube-api

infinite-scroll