變空RecyclerView

Question

這是我第一次使用RecyclerView，我有問題。我試圖讓我查看一個DrawerFragment。抽屜菜單工作正常，但我不能在那裏看到RecyclerView。誰能幫我？

這是我的片段的佈局：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
xmlns:tools="http://schemas.android.com/tools" 
android:layout_width="match_parent" 
android:layout_height="match_parent" 
android:background="#DADADA" 
tools:context="com.example.entwicklung1.designtestapp.NavigationDrawerFragment" 
android:orientation="horizontal"> 

<LinearLayout 
    android:id="@+id/linid" 
    android:layout_width="match_parent" 
    android:layout_height="120dp" 
    android:background="#0064a7" 
    android:paddingLeft="20dp"> 

    <ImageView 
     android:layout_width="240dp" 
     android:layout_height="120dp" 
     android:elevation="20dp" 
     android:gravity="center_vertical" 
     android:src="@drawable/zanderlogo" /> 
</LinearLayout> 

<android.support.v7.widget.RecyclerView 
    android:id="@+id/drawerList" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 

    ></android.support.v7.widget.RecyclerView> 

</LinearLayout> 

下面的代碼：

public class NavigationDrawerFragment extends Fragment { 
private RecyclerView recyclerView; 

public static final String PREF_FILE_NAME = "testpref"; 
public static final String KEY_USER_LEARNED_DRAWNER = "user_learned_drawer"; 
private ActionBarDrawerToggle mDrawerToggle; 
private DrawerLayout mDrawerLayout; 
private MyAdapter adapter; 

private boolean mUserLearnedDrawer; 
private boolean mFromSavedInstanceState; 
private View containerView; 

public NavigationDrawerFragment() { 
    // Required empty public constructor 
} 

public List<Information> getData(){ 
    List<Information> data = new ArrayList<>(); 
    int[] icons={R.drawable.ic_number1,R.drawable.ic_number2,R.drawable.ic_number3,R.drawable.ic_number4,R.drawable.ic_number5}; 
    String[] titles ={"News", "Produkte","Homepage","Kontakt","Anfahrt"}; 

    for(int i=0;i<titles.length; i++){ 
     Information current=new Information(); 
     current.iconId=icons[i]; 
     current.title=titles[i]; 
     data.add(current); 
    } 
    return data; 
} 

@Override 
public void onCreate(@Nullable Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    mUserLearnedDrawer = Boolean.valueOf(readFromPreferences(getActivity(), KEY_USER_LEARNED_DRAWNER, "false")); 
    mFromSavedInstanceState = savedInstanceState != null ? true : false; 

} 

@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, 
         Bundle savedInstanceState) { 
    // Inflate the layout for this fragment 
    View layout=inflater.inflate(R.layout.fragment_navigation_drawer, container, false); 
    recyclerView=(RecyclerView)layout.findViewById(R.id.drawerList); 
    adapter = new MyAdapter(getActivity(),getData()); 
    recyclerView.setLayoutManager(new LinearLayoutManager(getActivity())); 
    recyclerView.setAdapter(adapter); 
    return layout; 
} 




public void setUp(int fragmentId, DrawerLayout drawerLayout, final Toolbar toolbar) { 
    containerView=getActivity().findViewById(fragmentId); 
    mDrawerLayout = drawerLayout; 
    mDrawerToggle = new ActionBarDrawerToggle(getActivity(), 
      drawerLayout, toolbar, R.string.drawer_open, R.string.drawer_close) { 

     @Override 
     public void onDrawerOpened(View drawerView) { 
      super.onDrawerOpened(drawerView); 
      if(!mUserLearnedDrawer){ 
       mUserLearnedDrawer=true; 
       saveToPreferences(getActivity(),KEY_USER_LEARNED_DRAWNER,mUserLearnedDrawer+""); 
      } 
      getActivity().supportInvalidateOptionsMenu(); 
     } 

     @Override 
     public void onDrawerClosed(View drawerView) { 
      super.onDrawerClosed(drawerView); 
      getActivity().supportInvalidateOptionsMenu(); 

     } 
    }; 

    mDrawerLayout.setDrawerListener(mDrawerToggle); 
    mDrawerLayout.post(new Runnable() { 
     @Override 
     public void run() { 
      mDrawerToggle.syncState(); 
      if(!mUserLearnedDrawer && !mFromSavedInstanceState){ 
       mDrawerLayout.openDrawer(containerView); 
      } 
     } 
    }); 
} 

public static void saveToPreferences(Context context, String preferenceName, String preferenceValue) { 
    SharedPreferences sharedPreferences = context.getSharedPreferences(PREF_FILE_NAME, Context.MODE_PRIVATE); 
    SharedPreferences.Editor editor = sharedPreferences.edit(); 

    editor.putString(preferenceName, preferenceValue); 
    editor.apply(); 
} 

public static String readFromPreferences(Context context, String preferenceName, String defaultValue) { 
    SharedPreferences sharedPreferences = context.getSharedPreferences(PREF_FILE_NAME, Context.MODE_PRIVATE); 
    return sharedPreferences.getString(preferenceName, defaultValue); 
} 
} 

而這裏RecyclerView適配器：

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder>{ 
private LayoutInflater inflater; 
List<Information> data = Collections.emptyList(); 

public MyAdapter(Context context,List<Information> data) { 
    inflater=LayoutInflater.from(context); 
} 

@Override 
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { 
    View view = inflater.inflate(R.layout.custom_row,parent,false); 
    MyViewHolder holder = new MyViewHolder(view); 
    return holder; 
} 

@Override 
public void onBindViewHolder(MyViewHolder holder, int position) { 

    Information current = data.get(position); 
    holder.title.setText(current.title); 
    holder.icon.setImageResource(current.iconId); 
} 

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

class MyViewHolder extends RecyclerView.ViewHolder { 
    TextView title; 
    ImageView icon; 

    public MyViewHolder(View itemView) { 
     super(itemView); 
     title = (TextView) itemView.findViewById(R.id.listText); 
     icon = (ImageView)itemView.findViewById(R.id.listIcon); 
    } 
} 
} 

我到底做錯了什麼？

Answer 1

您不在適配器構造函數中設置數據。所以，你的數據是空的。

List<Information> data = Collections.emptyList(); 

    public MyAdapter(Context context,List<Information> data) { 
     inflater=LayoutInflater.from(context); 
     this.data = data; 
     ^^^^^^^^^^^^^^^^ add this statement 
    } 

更新：

需要更改頂部的LinearLayout以 「垂直」