ListView的片段錯誤內

Question

我的片段：

public class NewsFragment extends ListFragment { 
 

 
    private ProgressDialog pDialog; 
 

 
    // URL to get contacts JSON 
 
    private static String url = "url"; 
 

 
    // JSON Node names 
 
    private static final String TAG_NEWS = "news"; 
 
    private static final String TAG_ID = "id"; 
 
    private static final String TAG_JUDUL = "judul"; 
 
    private static final String TAG_TGL = "tanggal"; 
 
    private static final String TAG_ISI = "isi"; 
 
    private static final String TAG_SUMBER = "sumber"; 
 
    private static final String TAG_GAMBAR = "gambar"; 
 

 
    // contacts JSONArray 
 
    JSONArray news = null; 
 

 
    // Hashmap for ListView 
 
    ArrayList<HashMap<String, String>> newsList; 
 

 
    @Override 
 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
 
          Bundle savedInstanceState) { 
 
     View newsView = inflater.inflate(R.layout.fragment_news, container, false) ; 
 
     newsList = new ArrayList<HashMap<String, String>>(); 
 

 
     ListView lv = getListView(); 
 
     lv.setOnItemClickListener(new AdapterView.OnItemClickListener() { 
 

 
      @Override 
 
      public void onItemClick(AdapterView<?> parent, View view, 
 
            int position, long id) { 
 
       // getting values from selected ListItem 
 
       String judul = ((TextView) view.findViewById(R.id.judul)) 
 
         .getText().toString(); 
 
       String tanggal = ((TextView) view.findViewById(R.id.tglPublish)) 
 
         .getText().toString(); 
 
       String sumber = ((TextView) view.findViewById(R.id.sumber)) 
 
         .getText().toString(); 
 

 
       // Starting single contact activity 
 
       Intent in = new Intent(getActivity().getApplicationContext(), 
 
         NewsDetailActivity.class); 
 
       in.putExtra(TAG_JUDUL, judul); 
 
       in.putExtra(TAG_TGL, tanggal); 
 
       in.putExtra(TAG_SUMBER, sumber); 
 
       startActivity(in); 
 

 
      } 
 
     }); 
 

 
     // Calling async task to get json 
 
     new GetNews().execute(); 
 

 
     return newsView ; 
 
    } 
 

 
    /** 
 
    * Async task class to get json by making HTTP call 
 
    * */ 
 
    private class GetNews extends AsyncTask<Void, Void, Void> { 
 

 
     @Override 
 
     protected void onPreExecute() { 
 
      super.onPreExecute(); 
 
      // Showing progress dialog 
 
      pDialog = new ProgressDialog(getActivity()); 
 
      pDialog.setMessage("Mohon tunggu..."); 
 
      pDialog.setCancelable(false); 
 
      pDialog.show(); 
 

 
     } 
 

 
     @Override 
 
     protected Void doInBackground(Void... arg0) { 
 
      // Creating service handler class instance 
 
      ServiceHandler sh = new ServiceHandler(); 
 

 
      // Making a request to url and getting response 
 
      String jsonStr = sh.makeServiceCall(url, ServiceHandler.POST); 
 

 
      Log.d("Response: ", "> " + jsonStr); 
 

 
      if (jsonStr != null) { 
 
       try { 
 
        JSONObject jsonObj = new JSONObject(jsonStr); 
 

 
        // Getting JSON Array node 
 
        news = jsonObj.getJSONArray(""); 
 

 
        // looping through All Contacts 
 
        for (int i = 0; i < news.length(); i++) { 
 
         JSONObject c = news.getJSONObject(i); 
 

 
         String id = c.getString(TAG_ID); 
 
         String judul = c.getString(TAG_JUDUL); 
 
         String tgl = c.getString(TAG_TGL); 
 
         String sumber = c.getString(TAG_SUMBER); 
 
//      String gambar = c.getString(TAG_GENDER); 
 

 

 
         // tmp hashmap for single contact 
 
         HashMap<String, String> news = new HashMap<String, String>(); 
 

 
         // adding each child node to HashMap key => value 
 
         news.put(TAG_ID, id); 
 
         news.put(TAG_JUDUL, judul); 
 
         news.put(TAG_TGL, tgl); 
 
         news.put(TAG_SUMBER, sumber); 
 

 
         // adding contact to contact list 
 
         newsList.add(news); 
 
        } 
 
       } catch (JSONException e) { 
 
        e.printStackTrace(); 
 
       } 
 
      } else { 
 
       Log.e("ServiceHandler", "Couldn't get any data from the url"); 
 
      } 
 

 
      return null; 
 
     } 
 

 
     @Override 
 
     protected void onPostExecute(Void result) { 
 
      super.onPostExecute(result); 
 
      // Dismiss the progress dialog 
 
      if (pDialog.isShowing()) 
 
       pDialog.dismiss(); 
 
      /** 
 
      * Updating parsed JSON data into ListView 
 
      * */ 
 
      ListAdapter adapter = new SimpleAdapter(
 
        getActivity().getApplicationContext(), newsList, 
 
        R.layout.list_item, new String[] { TAG_JUDUL, TAG_TGL, 
 
        TAG_SUMBER }, new int[] { R.id.judul, 
 
        R.id.tglPublish, R.id.sumber }); 
 

 
      setListAdapter(adapter); 
 
     } 
 

 
    } 
 

 
}

我的xml：

<?xml version="1.0" encoding="utf-8"?> 
 
<LinearLayout 
 
    xmlns:android="http://schemas.android.com/apk/res/android" 
 
    android:layout_width="match_parent" 
 
    android:layout_height="match_parent" 
 
    android:orientation="vertical" 
 
    android:layout_marginLeft="12dp" 
 
    android:layout_marginRight="12dp"> 
 

 
    <!-- Main ListView 
 
     Always give id value as list(@android:id/list) 
 
    --> 
 
    <ListView 
 
     android:id="@android:id/list" 
 
     android:layout_width="fill_parent" 
 
     android:layout_height="wrap_content"/> 
 

 
</LinearLayout>

list_item.xml：

<?xml version="1.0" encoding="utf-8"?> 
 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
 
    android:layout_width="fill_parent" 
 
    android:layout_height="wrap_content" 
 
    android:orientation="vertical" 
 
    android:padding="10dp" 
 
    android:paddingLeft="10dp" 
 
    android:paddingRight="10dp" > 
 

 
    <!-- Judul --> 
 

 
    <TextView 
 
     android:id="@+id/judul" 
 
     android:layout_width="fill_parent" 
 
     android:layout_height="wrap_content" 
 
     android:paddingBottom="2dip" 
 
     android:paddingTop="6dip" 
 
     android:textColor="#43bd00" 
 
     android:textSize="16sp" 
 
     android:textStyle="bold" /> 
 

 
    <!-- Tgl Publish --> 
 
    <TextView 
 
     android:id="@+id/tglPublish" 
 
     android:layout_width="fill_parent" 
 
     android:layout_height="wrap_content" 
 
     android:paddingBottom="2dip" 
 
     android:textColor="#acacac" /> 
 

 
    <!-- Sumber --> 
 
    <TextView 
 
     android:id="@+id/sumber" 
 
     android:layout_width="fill_parent" 
 
     android:layout_height="wrap_content" 
 
     android:gravity="left" 
 
     android:textColor="#5d5d5d" 
 
     android:textStyle="bold" /> 
 
    <ImageView 
 
     android:layout_width="wrap_content" 
 
     android:layout_height="wrap_content" /> 
 

 
</LinearLayout>

和錯誤日誌：

05-20 00:24:41.091 20376-20376/com.emaszda.nutrisibunda E/AndroidRuntime﹕ FATAL EXCEPTION: main 
    java.lang.IllegalStateException: Content view not yet created 
      at android.support.v4.app.ListFragment.ensureList(ListFragment.java:328) 
      at android.support.v4.app.ListFragment.getListView(ListFragment.java:222) 
      at com.emaszda.nutrisibunda.NewsFragment.onCreateView(NewsFragment.java:58) 
      at android.support.v4.app.Fragment.performCreateView(Fragment.java:1786) 
      at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:953) 
      at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1136) 
      at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:739) 
      at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1499) 
      at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:488) 
      at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141) 
      at android.support.v4.view.ViewPager.populate(ViewPager.java:1073) 
      at android.support.v4.view.ViewPager.populate(ViewPager.java:919) 
      at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1441) 
      at android.view.View.measure(View.java:15891) 
      at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5035) 
      at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) 
      at android.view.View.measure(View.java:15891) 
      at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5035) 
      at android.support.v7.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:453) 
      at android.view.View.measure(View.java:15891) 
      at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5035) 
      at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) 
      at android.view.View.measure(View.java:15891) 
      at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5035) 
      at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404) 
      at android.widget.LinearLayout.measureVertical(LinearLayout.java:695) 
      at android.widget.LinearLayout.onMeasure(LinearLayout.java:588) 
      at android.view.View.measure(View.java:15891) 
      at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5035) 
      at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) 
      at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2208) 
      at android.view.View.measure(View.java:15891) 
      at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1957) 
      at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1156) 
      at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1336) 
      at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1056) 
      at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5542) 
      at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749) 
      at android.view.Choreographer.doCallbacks(Choreographer.java:562) 
      at android.view.Choreographer.doFrame(Choreographer.java:532) 
      at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735) 
      at android.os.Handler.handleCallback(Handler.java:730) 
      at android.os.Handler.dispatchMessage(Handler.java:92) 
      at android.os.Looper.loop(Looper.java:137) 
      at android.app.ActivityThread.main(ActivityThread.java:5162) 
      at java.lang.reflect.Method.invokeNative(Native Method) 
      at java.lang.reflect.Method.invoke(Method.java:525) 
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:756) 
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:572) 
      at miui.dexspy.DexspyInstaller.main(DexspyInstaller.java:171) 
      at dalvik.system.NativeStart.main(Native Method) 

Answer 1

作爲onCreateView：

創建並返回與該片段相關聯的視圖的層次結構。 由於該方法沒有返回視圖，因此您將無法通過getListView（）訪問 ListView。

把getListView()在onViewCreated()方法象下面這樣：

@Override 
public void onViewCreated(View view, Bundle savedInstanceState) { 
    super.onViewCreated(view, savedInstanceState); 
    ListView lv = getListView(); 
    lv.setOnItemClickListener(new AdapterView.OnItemClickListener() { 

     @Override 
     public void onItemClick(AdapterView<?> parent, View view, 
           int position, long id) { 
      // getting values from selected ListItem 
      String judul = ((TextView) view.findViewById(R.id.judul)) 
        .getText().toString(); 
      String tanggal = ((TextView) view.findViewById(R.id.tglPublish)) 
        .getText().toString(); 
      String sumber = ((TextView) view.findViewById(R.id.sumber)) 
        .getText().toString(); 

      // Starting single contact activity 
      Intent in = new Intent(getActivity().getApplicationContext(), 
        NewsDetailActivity.class); 
      in.putExtra(TAG_JUDUL, judul); 
      in.putExtra(TAG_TGL, tanggal); 
      in.putExtra(TAG_SUMBER, sumber); 
      startActivity(in); 

     } 
    }); 
} 

onViewCreated在api level 13增加，因此，如果低於13你的minSdkVersion然後使用onActivityCreated獲得列表視圖對象。

Answer 2

只是覆蓋onActivityCreated，把你的代碼：

// Calling async task to get json 
     new GetNews().execute(); 

這裏的問題是，你想它尚未建立時，操作UI，bacuse onCreateView沒有做return語句又

Answer 3

在onActivityCreated()而不是onCreateView()內調用GetNews().execute();方法，因爲在啓動AsyncTask時，您的視圖甚至尚未創建。

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

Answer 4

將這個ListView lv = getListView();代碼onActivityCreated()或您的片段