Retrofit RecyclerView不工作在標籤佈局

Question

我一直在試圖實現在使用改造庫顯示分析數據的片段內的回收站視圖。每當我運行項目時，列表不顯示，監視器顯示「E/RecyclerView：沒有附加適配器;跳過佈局」。這裏是我的代碼： MainActivity：

package com.example.ahmed.newsapp 

import android.os.Bundle; 
import android.support.v4.view.ViewPager; 
import android.support.v7.app.AppCompatActivity; 
import android.support.design.widget.TabLayout; 

public class MainActivity extends AppCompatActivity { 
private static final String TAG = MainActivity.class.getSimpleName(); 
private static final int ACTIVITY_NUM = 0; 
// TODO - insert your themoviedb.org API KEY here 
private final static String API_KEY = "<API KEY CENSORED>"; 


@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    // Find the view pager that will allow the user to swipe between fragments 
    ViewPager viewPager = (ViewPager) findViewById(R.id.viewpager); 

    // Create an adapter that knows which fragment should be shown   

    FragmentAdapter adapter = new FragmentAdapter(getSupportFragmentManager 
    ()); 
    // Set the adapter onto the view pager 
    viewPager.setAdapter(adapter); 
    TabLayout ob=(TabLayout) findViewById(R.id.sliding_tabs); 
    ob.setupWithViewPager(viewPager); 
} 
} 

FragmentAdapter：

package com.example.ahmed.newsapp; 

import android.support.v4.app.Fragment; 
import android.support.v4.app.FragmentManager; 
import android.support.v4.app.FragmentPagerAdapter; 

/** 
* Created by ahmed on 3/22/2017. 
*/ 

public class FragmentAdapter extends FragmentPagerAdapter { 
private String tabs[]=new String[]{"Home","Family Members","Colors"}; 
public FragmentAdapter(FragmentManager fm){ 
    super(fm); 
} 

@Override 
public Fragment getItem(int position) { 
    switch(position){ 
     case 0: 
      return new HomeActivity(); 
     case 1: 
      return new HomeActivity(); 
     /* case 2: 
      return new ColorFragment();*/ 
    } 
    return null; 
} 
@Override 
public CharSequence getPageTitle(int position) { 
return tabs[position]; 


} 


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

NewsAdapter：

package com.example.ahmed.newsapp; 



/** 
    * Created by ahmed on 27-08-17. 
    */ 
import android.content.Context; 
import android.support.v7.widget.RecyclerView; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.LinearLayout; 
import android.widget.TextView; 

import java.util.List; 

public class NewsAdapter extends RecyclerView.Adapter<NewsAdapter.NewsViewHolder> { 

private List<News> news; 
private int rowLayout; 
private Context context; 


public static class NewsViewHolder extends RecyclerView.ViewHolder { 
    LinearLayout moviesLayout; 
    TextView movieTitle; 
    TextView data; 
    TextView movieDescription; 
    TextView rating; 


    public NewsViewHolder(View v) { 
     super(v); 
     moviesLayout = (LinearLayout) v.findViewById(R.id.movies_layout); 
     movieTitle = (TextView) v.findViewById(R.id.title); 
     data = (TextView) v.findViewById(R.id.subtitle); 
     movieDescription = (TextView) v.findViewById(R.id.description); 
     rating = (TextView) v.findViewById(R.id.rating); 
    } 
} 

public NewsAdapter(List<News> news, Context context) { 
    this.news = news; 
    // this.rowLayout = rowLayout; 
    this.context = context; 
} 

@Override 
public NewsViewHolder onCreateViewHolder(ViewGroup parent, 
             int viewType) { 
    View view = LayoutInflater.from(parent.getContext()) 
      .inflate(R.layout.list_item_news, parent, false); 
    return new NewsViewHolder(view); 
} 


@Override 
public void onBindViewHolder(NewsViewHolder holder, final int position) { 
    holder.movieTitle.setText(news.get(position).getTitle()); 
    holder.data.setText(news.get(position).getReleaseDate()); 
    holder.movieDescription.setText(news.get(position).getOverview()); 
    holder.rating.setText(news.get(position).getVoteAverage().toString()); 
} 

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

HomeActivity：

package com.example.ahmed.newsapp; 

import android.os.Bundle; 
import android.support.annotation.Nullable; 
import android.support.v4.app.Fragment; 
import android.support.v7.widget.LinearLayoutManager; 
import android.support.v7.widget.RecyclerView; 
import android.util.Log; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.Toast; 

import java.util.List; 

import retrofit2.Call; 
import retrofit2.Callback; 
import retrofit2.Response; 

import static android.content.ContentValues.TAG; 

public class HomeActivity extends Fragment { 

RecyclerView recyclerView; 
private final static String API_KEY = "<API KEY CENSORED>"; 
NewsAdapter adapter; 
List<News> news,dummy; 
View rootview; 
public HomeActivity() { 
    // Required empty public constructor 
} 
@Nullable 
@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, 
         Bundle savedInstanceState) { 
    rootview = inflater.inflate(R.layout.activity_home, container, false); 

    if (API_KEY.isEmpty()) { 
     Toast.makeText(getContext(), "Please obtain your API KEY first from themoviedb.org", Toast.LENGTH_LONG).show(); 
     return rootview; 
    } 

    ApiInterface apiService = 
      ApiClient.getClient().create(ApiInterface.class); 

    recyclerView = (RecyclerView) rootview.findViewById(R.id.home_page_recycler_view); 
    adapter= new NewsAdapter(dummy,getContext()); 
    Call<NewsResponse> call = apiService.getTopRatedMovies(API_KEY); 
    call.enqueue(new Callback<NewsResponse>() { 

     @Override 
     public void onResponse(Call<NewsResponse> call, Response<NewsResponse> response) { 
      news = response.body().getResults(); 
      adapter.notifyDataSetChanged(); 
      adapter=new NewsAdapter(news,getContext()); 

      recyclerView.setAdapter(adapter); 
      // adapter.setData(news); 
      Log.d(TAG, "Number of movies received: " + news.size()); 
     } 

     @Override 
     public void onFailure(Call<NewsResponse> call, Throwable t) { 
      // Log error here since request failed 
      Log.e(TAG, t.toString()); 
     } 
    }); 
    recyclerView.setHasFixedSize(true); 
    recyclerView.setLayoutManager(new LinearLayoutManager(getContext(), LinearLayoutManager.VERTICAL, false)); 
    return rootview; 
} 
} 

Answer 1

我THI NK問題是在你的FragmentAdapter類

只是從你的FragmentAdapter刪除return null;聲明如下面的代碼

@Override 
public Fragment getItem(int position) { 
    Fragment fragment=null; 
    switch(position){ 
     case 0: 
      fragment= new HomeActivity(); 
     case 1: 
      fragment= new HomeActivity(); 
     /* case 2: 
      return new ColorFragment();*/ 
    } 
    return fragment; 
} 

改變這種

recyclerView.setHasFixedSize(true); 
recyclerView.setLayoutManager(new LinearLayoutManager(getContext(), LinearLayoutManager.VERTICAL, false)); 
recyclerView = (RecyclerView) rootview.findViewById(R.id.home_page_recycler_view); 
adapter= new NewsAdapter(dummy,getContext()); 

Answer 2

你並不需要重新創建適配器的時候，當接受迴應。

它可能看起來像：

recyclerView = (RecyclerView) rootview.findViewById(R.id.home_page_recycler_view); 
recyclerView.setLayoutManager(new LinearLayoutManager(getActivity())); 
adapter = new NewsAdapter(null, getActivity()); 
recyclerView.setAdapter(adapter); 
Call<NewsResponse> call = apiService.getTopRatedMovies(API_KEY); 
call.enqueue(new Callback<NewsResponse>() { 

    @Override 
    public void onResponse(Call<NewsResponse> call, Response<NewsResponse> response) { 
     news = response.body().getResults(); 
     adapter.setData(news); 
     Log.d(TAG, "Number of movies received: " + news.size()); 
    } 

    ... 

而且在NewsAdapter：

... 

public void setData(Collection<News> newData) { 
    news.clear(); 
    news.addAll(newData); 
    notifyDataSetChanged(); 
} 

@Override 
public int getItemCount() { 
    return news == null ? 0 : news.size(); 
} 

...