在片段中調用findViewById返回null

我想在我的片段佈局中更改TextView，但是，無論如何，在調用findViewById時，我都會得到空值。這裏是我的片段佈局：在片段中調用findViewById返回null

<RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin" 
    android:paddingLeft="@dimen/activity_horizontal_margin" 
    android:paddingRight="@dimen/activity_horizontal_margin" 
    android:paddingTop="@dimen/activity_vertical_margin" 
    tools:context="com.example.kubacm.myweather.ShowMeWeather"> 

    <TextView 
     android:id="@+id/city_field" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_alignParentTop="true" 
     android:layout_centerHorizontal="true" 
     android:textAppearance="?android:attr/textAppearanceLarge" 
     android:textColor="@android:color/white" /> 
</RelativeLayout>

從主活動中調用片段：

@Override public void showWeather(JSONObject data){ 
     Bundle bundle = new Bundle(); 
     bundle.putString("data",data.toString()); 
     ShowMeWeather wf = new ShowMeWeather(); 
     wf.setArguments(bundle); 
     getSupportFragmentManager().beginTransaction().replace(R.id.activity_main,wf).addToBackStack(null).commit(); 
    }

，並在片段：

public class ShowMeWeather extends Fragment { 
    Typeface weatherFont; 
    TextView cityField; 

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

@Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
          Bundle savedInstanceState) { 
     // Inflate the layout for this fragment 
     View rootView = inflater.inflate(R.layout.fragment_show_me_weather, container, false); 
     cityField = (TextView)rootView.findViewById(R.id.city_field); 
     return rootView; 
    } 

@Override 
    public void onCreate(Bundle savedInstanceState){ 
     super.onCreate(savedInstanceState); 
     weatherFont = Typeface.createFromAsset(getActivity().getAssets(),"fonts/weather.ttf"); 

     renderWeather(); 
    } 

    public void renderWeather(){ 
     try{ 
      cityField.setText("Here should go my text"); 
     }catch (Exception e){ 
      Log.e("Simple Weather","there was an errror"); 
     } 
    } 
}

我試圖清理和Android Studio中，仍然重建我的項目當我嘗試使用cityField.SetText時，不斷收到NullPointerException

來源

2017-01-06 mr_kite

檢查片段生命週期這裏here onCreateView完成

後打電話給你的renderWeather方法

來源

2017-01-06 20:42:59

onCreateView方法後onCreate方法調用，所以cityField尚未初始化

來源

2017-01-06 20:37:13 firegloves

在片段中調用findViewById返回null

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