Question

我正在尝试提高移动应用的性能。我正在尝试使用AsyncTask。我已经查看了很多关于AsyncTask的文档，同时在这里查看了很多问题，但似乎无法让我的代码正常运行。

我见过在onPostExecute方法中设置适配器的示例，但这对我不起作用..

 @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_travel_updates);



        Twitter.initialize(this);

        new getTweets().execute();
    }


private class getTweets extends AsyncTask<Void, Void, Void>{


    @Override
    protected void onPreExecute() {
        super.onPreExecute();

        final RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
        recyclerView.setLayoutManager(new LinearLayoutManager(travel_updates.this));
    }

    @Override
    protected Void doInBackground(Void... params) {
        final UserTimeline searchTimeline = new UserTimeline.Builder().screenName("TflTravelAlerts")
                .maxItemsPerRequest(5)
                .build();

        final TweetTimelineRecyclerViewAdapter tweetAdapter =
                new TweetTimelineRecyclerViewAdapter.Builder(travel_updates.this)
                        .setTimeline(searchTimeline)
                        .setViewStyle(R.style.tw__TweetLightWithActionsStyle)
                        .build();
        return null;
    }

    @Override
    protected void onPostExecute(Void Void) {

recyclerView.setAdapter(tweetAdapter);

    }
  }
}

由于

Answer 1

在您的MainActivity中定义RecycleView，而不是onPreExecute的{{1}}方法。

使用AsyncTask方法，您可以设置onCreate。

RecyclerView

由于private RecyclerView recyclerView; @Override protected void onCreate(@Nullable Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_travel_updates); recyclerView = (RecyclerView) findViewById(R.id.recycler_view); recyclerView.setLayoutManager(new LinearLayoutManager(travel_updates.this)); Twitter.initialize(this); new getTweets().execute(); }方法中有UserTimeline和TweetTimelineRecyclerViewAdapter（与UI不在同一个线程中），因此无法在doInBackground中设置适配器。在UI线程上设置适配器。

doInBackground

然后@Override protected Void doInBackground(Void... params) { final UserTimeline searchTimeline = new UserTimeline.Builder().screenName("TflTravelAlerts") .maxItemsPerRequest(5) .build(); final TweetTimelineRecyclerViewAdapter tweetAdapter = new TweetTimelineRecyclerViewAdapter.Builder(travel_updates.this) .setTimeline(searchTimeline) .setViewStyle(R.style.tw__TweetLightWithActionsStyle) .build(); runOnUiThread(new Runnable() { @Override public void run() { recyclerView.setAdapter(tweetAdapter); }); // I don't think you need to return anything if your method uses void?? return null; }应为空。

在AsyncTask中setAdapter的位置？

1 个答案: