Tablayout + view pager未在位置0显示片段

Question

我的应用程序有2个标签，有两种不同的布局。当我运行应用程序时，应该在tab1（位置0）中显示的片段显示在tab2中，并且应该在tab2（位置1）中的片段不显示。此外，当我滑动屏幕时，tablayout中的标签焦点没有改变

我在下面给出了我的代码

MainActivity.java

public class MainActivity extends AppCompatActivity implements TabLayout.OnTabSelectedListener 
{
    TabLayout tabLayoutTL;
    TabLayout.Tab linearTab, gridTab;
    ViewPager viewPagerVP;
    ViewPagerAdapter viewPagerAdapter;

    @Override
    public void onTabSelected(TabLayout.Tab tab) {
        viewPagerVP.setCurrentItem(tab.getPosition());
    }

    @Override
    public void onTabUnselected(TabLayout.Tab tab) {
    }

    @Override
    public void onTabReselected(TabLayout.Tab tab) {
    }


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        viewPagerVP = (ViewPager)findViewById(R.id.viewPagerVP);
        viewPagerAdapter = new ViewPagerAdapter(getSupportFragmentManager());
        viewPagerVP.setAdapter(viewPagerAdapter);

        tabLayoutTL = (TabLayout)findViewById(R.id.tabLayoutTL);
        linearTab = tabLayoutTL.newTab();
        gridTab = tabLayoutTL.newTab();

        linearTab.setText("Linear");
        gridTab.setText("Grid");

        tabLayoutTL.addTab(linearTab, 0);
        tabLayoutTL.addTab(gridTab, 1);
        tabLayoutTL.setOnTabSelectedListener(this);
    }
}

MainFragment.java

public class MainFragment extends Fragment {

    private static final String FRAG_TYPE = "frag_type";
    int fragType;
    RecyclerView recyclerViewRv;

    public MainFragment() {}

    public static MainFragment newInstance(int fragType) {
        MainFragment mainFragment = new MainFragment();
        Bundle args = new Bundle();
        args.putInt(FRAG_TYPE, fragType);
        mainFragment.setArguments(args);
        return mainFragment;
    }

    private void initialize() {
        recyclerViewRv = (RecyclerView)getActivity().findViewById(R.id.recyclerViewRv);
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        initialize();
        new BackBone().execute();
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {
            fragType = getArguments().getInt(FRAG_TYPE);
        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_linear, container, false);
    }

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
    }

    @Override
    public void onDetach() {
        super.onDetach();
    }

    class BackBone extends AsyncTask<Void, Void, ArrayList<DataRecord>> {

        ProgressDialog progressDialog;
        private static final String flickrUrl = "http://www.flickr.com/services/feeds/photos_public.gne?tags=soccer&format=json&nojsoncallback=1";

        private String getData() {
            HttpClient httpClient = new DefaultHttpClient();
            HttpGet httpGet = new HttpGet(flickrUrl);
            try {
                HttpResponse httpResponse = httpClient.execute(httpGet);
                HttpEntity httpEntity = httpResponse.getEntity();
                String data = EntityUtils.toString(httpEntity);
                return data;
            } catch (Exception e) {
                return "exception";
            }
        }

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            progressDialog = new ProgressDialog(getActivity());
            progressDialog.setTitle("Loading");
            progressDialog.setMessage("Please wait .......");
            progressDialog.show();
        }

        @Override
        protected ArrayList<DataRecord> doInBackground(Void... params) {
            ArrayList<DataRecord> dataRecords = new ArrayList<>();
            try {
                JSONObject jsonObject = new JSONObject(getData());
                JSONArray jsonArray = jsonObject.getJSONArray("items");
                for (int i = 0 ; i < jsonArray.length() ; i++) {
                    JSONObject jsonObject1 = jsonArray.getJSONObject(i);
                    DataRecord dataRecord = new DataRecord();
                    dataRecord.setName(jsonObject1.getString("title"));
                    JSONObject mediaJSONObject = jsonObject1.getJSONObject("media");
                    dataRecord.setUrl(mediaJSONObject.getString("m"));
                    dataRecords.add(dataRecord);
                }
            } catch (Exception e) {}
            return dataRecords;
        }

        @Override
        protected void onPostExecute(ArrayList<DataRecord> dataRecords) {
            super.onPostExecute(dataRecords);
            DataRecordAdapter dataRecordAdapter = new DataRecordAdapter(getActivity(), dataRecords, fragType);
            if (fragType == 1) {
                recyclerViewRv.setLayoutManager(new LinearLayoutManager(getActivity()));
                recyclerViewRv.setBackgroundColor(Color.GREEN);
            } else if (fragType == 2){
                recyclerViewRv.setLayoutManager(new GridLayoutManager(getActivity(), 2));
                recyclerViewRv.setBackgroundColor(Color.BLUE);
            }
            recyclerViewRv.setAdapter(dataRecordAdapter);
            progressDialog.dismiss();
        }

    }
}

ViewPagerAdapter.java

public class ViewPagerAdapter extends FragmentStatePagerAdapter {

    public ViewPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int position) {
        switch (position) {
            case 0 :
                MainFragment mainFragment = MainFragment.newInstance(1);
                return mainFragment;
            case 1 :
                MainFragment mainFragment1 = MainFragment.newInstance(2);
                return mainFragment1;
            default :
                return null;
        }
    }

    @Override
    public int getCount() {
        return 2;
    }
}

我确信碎片没有问题。我认为问题在于tablayout。我无法弄清问题的确切位置。

DataRecordAdapter.java

public class DataRecordAdapter extends RecyclerView.Adapter<DataRecordAdapter.MyViewHolder> {

    ArrayList<DataRecord> dataRecords;
    Context context;
    int flag;
    LayoutInflater layoutInflater;

    public DataRecordAdapter(Context context, ArrayList<DataRecord> dataRecords, int flag) {
        this.context = context;
        this.dataRecords = dataRecords;
        this.flag = flag;
        layoutInflater = (LayoutInflater.from(context));
    }

    @Override
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view;
        if (flag == 1) {
            view = layoutInflater.inflate(R.layout.linear_data_layout, parent, false);
        } else {
            view = layoutInflater.inflate(R.layout.grid_data_layout, parent, false);
        }
        MyViewHolder myViewHolder = new MyViewHolder(view);
        return myViewHolder;
    }

    @Override
    public void onBindViewHolder(MyViewHolder holder, int position) {
        DataRecord dataRecord = dataRecords.get(position);
        holder.textViewTV.setText(dataRecord.getName());
        Picasso.with(context).load(dataRecord.getUrl()).into(holder.imageViewIV);
    }

    @Override
    public int getItemCount() {
        return dataRecords.size();
    }

    class MyViewHolder extends RecyclerView.ViewHolder {
        TextView textViewTV;
        ImageView imageViewIV;
        public MyViewHolder(View itemView) {
            super(itemView);
            textViewTV = (TextView)itemView.findViewById(R.id.textViewTV);
            imageViewIV = (ImageView)itemView.findViewById(R.id.imageViewIV);
        }
    }

}

DataRecord.java

public class DataRecord {
    String name, url;

    public String getName() {
        return name;
    }
[![enter image description here][1]][1]
    public void setName(String name) {
        this.name = name;
    }

    public String getUrl() {
        return url;
    }

    public void setUrl(String url) {
        this.url = url;
    }
}

看看图片家伙。选项卡1为空，选项卡2显示选项卡1上的内容。选项卡2内容不显示。

Answer 1

你应该致电：

onCreate

在MainActivity的class StdOutListener(StreamListener): tweet_number=0 # class variable def __init__(self,max_tweets): self.max_tweets=max_tweets # max number of tweets def on_data(self, data): self.tweet_number+=1 try: tweet = json.loads(data) with open('your_data.json', 'a') as my_file: json.dump(tweet, my_file) except BaseException: print('Error') pass if self.tweet_number>=self.max_tweets: sys.exit('Limit of '+str(self.max_tweets)+' tweets reached.') def on_error(self, status): print ("Error " + str(status)) if status == 420: print("Rate Limited") return False l = StdOutListener(1000) # Here you can set your maximum number of tweets (1000 in this example) 函数上。

Answer 2

我知道线程不是活的，但这可能会帮助某人并节省我必须花费的一天。我遇到了同样的问题。问题是两个片段上的viewID相同。当然，viewpager和fragment应该已经解决了这个问题，但是他们并没有这样做。

对我来说，这是两个不同的片段，即 FragmentHome 和 FragmentNotification 。两者都必须使用 recyclerView 显示数据。 Home是左边的第一个片段，接下来是通知。但首先显示为空白，主页内容显示在预期通知内容的下一个选项卡上。由于两者都有相同的recyclerViews，我写了一个 layout_recycler_wrapper.xml 来重用代码。其中 RelativeLayout （ R.id.rl_wrapper ）与 recyclerView 在一起。 根本原因是我使用<include>在两个片段布局文件中包含了这个layout_recycler_wrapper。因此，包装器viewGroup（ RelativeLayout ）的相同ID（ R.id.rl_wrapper ）被多次使用。

然后我直接在片段的xml文件中编写了包装代码，而不是使用<include>标记。然后在相应的文件中将 RelativeLayout 包装的ID更改为 R.id.rl_wrapper_home 和 R.id.rl_wrapper_notification 。

在下一次运行中，第一个片段神奇地 FragmentHome 。 Yahooo .....：）

因此，最终，使用具有相同ID的视图（即使在不同的片段中）也会产生问题。这是一个可能的原因。检查您的XML文件并删除ID的可能重用，这也可能为您解决问题。