Фрагмент Android с ошибкой Listadapter (не удалось запустить Activity ComponentInfo)

Question

Я начинаю программирование приложений для Android.

Когда я использую фрагмент с ListAdapter, я сталкиваюсь с ошибкой.

это исходный код,

public class RegReceiptFragment extends Fragment { 

    private Context mContext; 

    private ListView mRegisteredPLUList; 

    private List<String> mDescTestArr; 

    private RegReceiptFragmentListAdapter mRegReceiptListAdapter; 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 

     View myFragmentView = inflater.inflate(R.layout.regmain_receipt_layout, container, false); 

     mRegisteredPLUList = (ListView) getActivity().findViewById(R.id.reason_list); 

     mDescTestArr = new ArrayList<String>(); 

     testPutListItem(null); 

     return myFragmentView; 

    } 

    @Override 
    public void onActivityCreated(Bundle savedInstanceState) { 
     super.onActivityCreated(savedInstanceState); 

     mContext = getActivity().getBaseContext(); 

     mRegReceiptListAdapter = new RegReceiptFragmentListAdapter(mContext, R.layout.common_list_item, mDescTestArr); 
     if (mRegReceiptListAdapter == null) 
      Log.d("masstest", "listview is null!!!"); 
     else 
      mRegisteredPLUList.setAdapter(mRegReceiptListAdapter); 
    } 

    private void testPutListItem(String value) { 
     if (value == null) { 
      mDescTestArr.add("BAD!!"); 
      mDescTestArr.add("HAHAHAHA!!"); 
      mDescTestArr.add("GEE GEE!!"); 
     } else { 
      mDescTestArr.add(value); 
     } 

    } 
} 

public class RegReceiptFragmentListAdapter extends ArrayAdapter<String> { 

    private Context mContext; 
    private final int mResourceId; 
    private List<String> mTestDescArr; 

    public RegReceiptFragmentListAdapter(Context context, 
      int textViewResourceId, List<String> arry) { 
     super(context, textViewResourceId, arry); 
     mContext = context; 
     mResourceId = textViewResourceId; 
     mTestDescArr = arry; 
    } 

    public View getView(int position, View convertView, ViewGroup parent) { 

     ReasonListHolder holder; 
     View row = convertView; 

     if (row == null) { 
      LayoutInflater inflater = (LayoutInflater) mContext 
        .getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
      row = inflater.inflate(mResourceId, parent, false); 

      holder = new ReasonListHolder(); 

      holder.mDescTitle = (TextView) row.findViewById(R.id.list_description); 
      holder.mQuantity = (TextView) row.findViewById(R.id.list_quantity); 
      holder.mPrice = (TextView) row.findViewById(R.id.list_price); 

      row.setTag(holder); 
     } else { 
      holder = (ReasonListHolder) row.getTag(); 
     } 

     holder.mDescTitle.setText(mTestDescArr.get(position)); 
     holder.mQuantity.setText(String.valueOf(position)); 
     holder.mPrice.setText(String.valueOf(position)); 

     return (row); 
    } 

    class ReasonListHolder { 
     TextView mQuantity; 
     TextView mDescTitle; 
     TextView mPrice; 
    } 
} 

и код ошибки рядом

01-12 09:16:01.950: W/dalvikvm(26465): threadid=1: thread exiting with uncaught exception (group=0x41884700) 
01-12 09:16:01.950: E/AndroidRuntime(26465): FATAL EXCEPTION: main 
01-12 09:16:01.950: E/AndroidRuntime(26465): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.sam4s.sample.fragment.test004/com.sam4s.sample.fragment.test004.MainActivity}: java.lang.NullPointerException 
01-12 09:16:01.950: E/AndroidRuntime(26465): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2211) 
01-12 09:16:01.950: E/AndroidRuntime(26465): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261) 
01-12 09:16:01.950: E/AndroidRuntime(26465): at android.app.ActivityThread.access$600(ActivityThread.java:141) 
01-12 09:16:01.950: E/AndroidRuntime(26465): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256) 
01-12 09:16:01.950: E/AndroidRuntime(26465): at android.os.Handler.dispatchMessage(Handler.java:99) 
01-12 09:16:01.950: E/AndroidRuntime(26465): at android.os.Looper.loop(Looper.java:137) 
01-12 09:16:01.950: E/AndroidRuntime(26465): at android.app.ActivityThread.main(ActivityThread.java:5103) 
01-12 09:16:01.950: E/AndroidRuntime(26465): at java.lang.reflect.Method.invokeNative(Native Method) 
01-12 09:16:01.950: E/AndroidRuntime(26465): at java.lang.reflect.Method.invoke(Method.java:525) 
01-12 09:16:01.950: E/AndroidRuntime(26465): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737) 
01-12 09:16:01.950: E/AndroidRuntime(26465): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 
01-12 09:16:01.950: E/AndroidRuntime(26465): at dalvik.system.NativeStart.main(Native Method) 
01-12 09:16:01.950: E/AndroidRuntime(26465): Caused by: java.lang.NullPointerException 
01-12 09:16:01.950: E/AndroidRuntime(26465): at com.sam4s.sample.fragment.test004.RegReceiptFragment.onActivityCreated(RegReceiptFragment.java:60) 
01-12 09:16:01.950: E/AndroidRuntime(26465): at android.support.v4.app.Fragment.performActivityCreated(Fragment.java:1794) 
01-12 09:16:01.950: E/AndroidRuntime(26465): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:967) 
01-12 09:16:01.950: E/AndroidRuntime(26465): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1126) 
01-12 09:16:01.950: E/AndroidRuntime(26465): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1108) 
01-12 09:16:01.950: E/AndroidRuntime(26465): at android.support.v4.app.FragmentManagerImpl.dispatchActivityCreated(FragmentManager.java:1917) 
01-12 09:16:01.950: E/AndroidRuntime(26465): at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:544) 
01-12 09:16:01.950: E/AndroidRuntime(26465): at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1171) 
01-12 09:16:01.950: E/AndroidRuntime(26465): at android.app.Activity.performStart(Activity.java:5143) 
01-12 09:16:01.950: E/AndroidRuntime(26465): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2184) 
01-12 09:16:01.950: E/AndroidRuntime(26465): ... 11 more 

активность находится рядом

public class MainActivity extends FragmentActivity { 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    requestWindowFeature(Window.FEATURE_NO_TITLE); 
    setContentView(R.layout.activity_main); 

    // Check whether the activity is using the layout version with 
    // the fragment_container FrameLayout. If so, we must add the first fragment 
    if (findViewById(R.id.fragment_container) != null) { 

     // However, if we're being restored from a previous state, 
     // then we don't need to do anything and should return or else 
     // we could end up with overlapping fragments. 
     if (savedInstanceState != null) { 
      return; 
     } 
    } 
} 
} 

и activity_main.xml является

<?xml version="1.0" encoding="utf-8"?> 
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" 
android:id="@+id/fragment_container" 
android:layout_width="match_parent" 
android:layout_height="match_parent" > 

     <fragment 
      android:id="@+id/fragment_two" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      class="com.sam4s.sample.fragment.test004.RegPLUFragment" /> 
</FrameLayout> 

Answer 1

Я нашел причину.

@Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
      ... 
      mRegisteredPLUList = (ListView) getActivity().findViewById(R.id.reason_list); 
      ... 
    } 

этот код должен быть перемещен в

@Override 
public void onActivityCreated(Bundle savedInstanceState) { 
    .... 
    mRegisteredPLUList = (ListView) getActivity().findViewById(R.id.reason_list); 
    .... 
} 

это misstake от моего кодирования без знания жизненного цикла фрагмента.

Спасибо!