回收利用json數據時Recycler視圖中的問題

我的問題是當我使用json創建回收視圖但它顯示異常任何人都可以解決這個問題與我的輝煌請幫我解決這個問題，我欣賞誰解決這個錯誤？回收利用json數據時Recycler視圖中的問題

public class MainActivity extends Activity { 
Button b; 
TextView tv; 
ListView lists; 
RecyclerView recyclerView; 
List<Your> yourss; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    recyclerView = (RecyclerView) findViewById(R.id.recycle); 
    LinearLayoutManager ll = new LinearLayoutManager(MainActivity.this); 
    recyclerView.setHasFixedSize(true); 
    recyclerView.setLayoutManager(ll); 
    new JsonTask().execute("http://yoursubshop.com/webservices/categories.php"); 
} 

public class JsonTask extends AsyncTask<String, String, List<Your>> { 
    @Override 
    protected List<Your> doInBackground(String... params) { 
     HttpURLConnection httpURLConnection = null; 
     BufferedReader bufferedReader = null; 
     try { 
      URL url = new URL(params[0]); 
      httpURLConnection = (HttpURLConnection) url.openConnection(); 
      InputStreamReader inputStreamReader = new InputStreamReader(httpURLConnection.getInputStream()); 
      bufferedReader = new BufferedReader(inputStreamReader); 
      StringBuffer sb = new StringBuffer(); 
      String line = ""; 
      while ((line = bufferedReader.readLine()) != null) { 
       sb.append(line); 
      } 
      String finaljson = sb.toString(); 
      JSONObject firstobject = new JSONObject(finaljson); 
      JSONArray firstarray = firstobject.getJSONArray("data"); 
          List<Your> yo = new ArrayList<>(); 
      for (int i = 0; i < firstarray.length(); i++) { 
       JSONObject finalobject = firstarray.getJSONObject(i); 
       Your yos = new Your(); 
       yos.category_id = finalobject.getString("category_id"); 
       yos.category_name = finalobject.getString("category_name"); 
       yo.add(yos); 
      } 
      return yo; 
     } catch (MalformedURLException e) { 
      e.printStackTrace(); 
     } catch (IOException e) { 
      e.printStackTrace(); 
     } catch (JSONException e) { 
      e.printStackTrace(); 
     } finally { 
      if (httpURLConnection != null) { 
       httpURLConnection.disconnect(); 
      } 
      try { 
       if (bufferedReader != null) { 

        bufferedReader.close(); 
       } 
      } catch (IOException e) { 
       e.printStackTrace(); 
      } 
     } 
     return null; 
    } 

    @Override 
    protected void onPostExecute(List<Your> result) { 
     super.onPostExecute(result); 
     Rvadapter listAdapter = new Rvadapter(MainActivity.this, yourss); 
     recyclerView.setAdapter(listAdapter); 
    } 
} 

public class Rvadapter extends RecyclerView.Adapter<Rvadapter.Myadapter> { 
    List<Your> yours = Collections.emptyList(); 

    Context c; 
    public class Myadapter extends RecyclerView.ViewHolder { 
     TextView id; 
     TextView name; 
     CardView cv; 
     public Myadapter(View itemView) { 
      super(itemView); 
      id = (TextView) itemView.findViewById(R.id.texts); 
      name = (TextView) itemView.findViewById(R.id.textsa); 
      cv = (CardView)itemView.findViewById(R.id.card); 
     } 
    } 
    public Rvadapter(Context c, List<Your> yours) { 
     this.yours = yours; 
     this.c = c; 


    } 
    @Override 
    public Myadapter onCreateViewHolder(ViewGroup parent, int viewType) { 
     View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.lists, parent, false); 
     Myadapter m = new Myadapter(v); 
     return m; 
    } 

    @Override 
    public void onBindViewHolder(Myadapter holder, int position) { 
     Your y = yours.get(position); 
     holder.id.setText(y.category_id); 
     holder.name.setText(y.category_name); 
    } 

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

    @Override 
    public void onAttachedToRecyclerView(RecyclerView recyclerView) { 
     super.onAttachedToRecyclerView(recyclerView); 
    } 
}

Eception程序

06-28 17:03:34.078 802-802/com.example.anilkumar.json E/AndroidRuntime: FATAL EXCEPTION: main 
java.lang.NullPointerException 
    at com.example.anilkumar.json.MainActivity$Rvadapter.getItemCount(MainActivity.java:154) 
    at android.support.v7.widget.RecyclerView.dispatchLayoutStep1(RecyclerView.java:3170) 
    at android.support.v7.widget.RecyclerView.onMeasure(RecyclerView.java:2782) 
    at android.view.View.measure(View.java:12723) 
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4698) 
    at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1369) 
    at android.widget.LinearLayout.measureVertical(LinearLayout.java:660) 
    at android.widget.LinearLayout.onMeasure(LinearLayout.java:553) 
    at android.view.View.measure(View.java:12723) 
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4698) 
    at android.widget.FrameLayout.onMeasure(FrameLayout.java:293) 
    at android.view.View.measure(View.java:12723) 
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4698) 
    at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1369) 
    at android.widget.LinearLayout.measureVertical(LinearLayout.java:660) 
    at android.widget.LinearLayout.onMeasure(LinearLayout.java:553) 
    at android.view.View.measure(View.java:12723) 
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4698) 
    at android.widget.FrameLayout.onMeasure(FrameLayout.java:293) 
    at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2092) 
    at android.view.View.measure(View.java:12723) 
    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1064) 
    at android.view.ViewRootImpl.handleMessage(ViewRootImpl.java:2442) 
    at android.os.Handler.dispatchMessage(Handler.java:99) 
    at android.os.Looper.loop(Looper.java:137) 
    at android.app.ActivityThread.main(ActivityThread.java:4424) 
    at java.lang.reflect.Method.invokeNative(Native Method) 
    at java.lang.reflect.Method.invoke(Method.java:511) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)

lists.xml

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
android:orientation="vertical" 
android:layout_width="match_parent" 
android:layout_height="match_parent"> 
<android.support.v7.widget.CardView 
    android:layout_width="300dp" 
    android:layout_height="80dp" 
    android:id="@+id/card"> 
<TextView 
android:layout_width="wrap_content" 
android:layout_height="wrap_content" 
android:id="@+id/texts" 
android:text="id" 
android:padding="20dp" 
android:layout_margin="20sp" 
android:textSize="20sp"/> 
<TextView 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:id="@+id/textsa" 
    android:layout_margin="20sp" 
    android:text="Resturants" 
    android:textSize="20sp"/> 
</android.support.v7.widget.CardView>

來源

2016-06-28 A.asha

的問題是，試圖讓計數時，你沒有初始化數組。嘗試更改爲。

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

來源

2016-06-28 11:43:45 toshkinl

錯誤解決，但應用不列入喪生，但數據並沒有顯示在屏幕上，這是什麼錯誤 –

那麼這意味着你沒有添加正確的項目到您的適配器。嘗試將您從onPostExecute（列表結果）獲得的結果添加到適配器，如#Drv所述。 – toshkinl

yess工作，但cardview之間很多的差距之間發生的項目之間我怎麼能解決這一個 –

在你onPostExecute，第一個變化

@Override 
protected void onPostExecute(List<Your> result) { 
    super.onPostExecute(result); 
    Rvadapter listAdapter = new Rvadapter(MainActivity.this, yourss); 
    recyclerView.setAdapter(listAdapter); 
}

與

@Override 
protected void onPostExecute(List<Your> result) { 
    super.onPostExecute(result); 
    Rvadapter listAdapter = new Rvadapter(MainActivity.this, result); 
    recyclerView.setAdapter(listAdapter); 
}

現在，檢查它是否工作或沒有。

編輯您的lists.xml與下面的代碼：

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:orientation="vertical" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content"> 
     <android.support.v7.widget.CardView 
      android:layout_width="300dp" 
      android:layout_height="80dp" 
      android:id="@+id/card"> 
       <TextView 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:id="@+id/texts" 
        android:text="id" 
        android:padding="20dp" 
        android:layout_margin="20sp" 
        android:textSize="20sp"/> 

       <TextView 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:id="@+id/textsa" 
        android:layout_margin="20sp" 
        android:text="Resturants" 
        android:textSize="20sp"/> 
     </android.support.v7.widget.CardView> 
    </LinearLayout>

來源

2016-06-28 11:45:59 Drv

yess工作，但cardview之間很多的差距之間發生的項目之間如何解決這一個 –

請張貼您的佈局文件爲cardview的Rvadapter的list_item。 – Drv

@ A.asha添加名爲lists.xml的佈局，以便我們提供幫助。 – Drv

回收利用json數據時Recycler視圖中的問題

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