getListView（）上的空指针

为什么我在lv = getListView();上得到空指针？getListView（）上的空指针

public class bListFragment extends ListFragment { 
static public final String STATE_CHECKED="com.tyczj.bowling.STATE_CHECKED"; 
OnLongListClickListener mListener; 
ListView lv; 
String name; 
long id; 

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

    lv = getListView(); //NullPointerException 
    lv.setTextFilterEnabled(true); 

    getListView().setChoiceMode(ListView.CHOICE_MODE_SINGLE); 
    getListView().setTextFilterEnabled(true); 

    getListView().setOnItemLongClickListener(new OnItemLongClickListener() { 

     @Override 
     public boolean onItemLongClick(AdapterView<?> arg0, View arg1, 
       int arg2, long arg3) { 

      Vibrator v = (Vibrator)getActivity().getSystemService(getActivity().VIBRATOR_SERVICE); 
      v.vibrate(new long [] {0,20,0,0}, -1); 
      TextView tv = (TextView)arg1.findViewById(R.id.bListTextView); 
      name = tv.getText().toString(); 
      try{ 
       id = Integer.parseInt(getRow(name)); 
       mListener.OnLongListClick(id); 
      }catch(CursorIndexOutOfBoundsException e){ 
       populateList(); 
      } 
      return false; 
     } 

    }); 

}

logcat的错误

11-22 12:48:39.170: E/AndroidRuntime(14259): FATAL EXCEPTION: main 
11-22 12:48:39.170: E/AndroidRuntime(14259): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.tyczj.bowling/com.tyczj.bowling.Tabs}: java.lang.NullPointerException 
11-22 12:48:39.170: E/AndroidRuntime(14259): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1751) 
11-22 12:48:39.170: E/AndroidRuntime(14259): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1767) 
11-22 12:48:39.170: E/AndroidRuntime(14259): at android.app.ActivityThread.access$1500(ActivityThread.java:122) 
11-22 12:48:39.170: E/AndroidRuntime(14259): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1005) 
11-22 12:48:39.170: E/AndroidRuntime(14259): at android.os.Handler.dispatchMessage(Handler.java:99) 
11-22 12:48:39.170: E/AndroidRuntime(14259): at android.os.Looper.loop(Looper.java:132) 
11-22 12:48:39.170: E/AndroidRuntime(14259): at android.app.ActivityThread.main(ActivityThread.java:4028) 
11-22 12:48:39.170: E/AndroidRuntime(14259): at java.lang.reflect.Method.invokeNative(Native Method) 
11-22 12:48:39.170: E/AndroidRuntime(14259): at java.lang.reflect.Method.invoke(Method.java:491) 
11-22 12:48:39.170: E/AndroidRuntime(14259): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:844) 
11-22 12:48:39.170: E/AndroidRuntime(14259): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:602) 
11-22 12:48:39.170: E/AndroidRuntime(14259): at dalvik.system.NativeStart.main(Native Method) 
11-22 12:48:39.170: E/AndroidRuntime(14259): Caused by: java.lang.NullPointerException 
11-22 12:48:39.170: E/AndroidRuntime(14259): at com.tyczj.bowling.BowlersListFragment.onCreate(BowlersListFragment.java:29) 
11-22 12:48:39.170: E/AndroidRuntime(14259): at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:702) 
11-22 12:48:39.170: E/AndroidRuntime(14259): at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:926) 
11-22 12:48:39.170: E/AndroidRuntime(14259): at android.app.BackStackRecord.run(BackStackRecord.java:578) 
11-22 12:48:39.170: E/AndroidRuntime(14259): at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1226) 
11-22 12:48:39.170: E/AndroidRuntime(14259): at android.app.Activity.performStart(Activity.java:4370) 
11-22 12:48:39.170: E/AndroidRuntime(14259): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1724)

来源

2011-11-22 tyczj

退房的documentation for ListActivity。

您首先需要一个布局文件（xml文件），其中包含一个ListView，其ID为：android:id="@android:id/list"。

第二你忘记设置你的Activity的内容视图：

super.onCreate(savedInstanceState); 
this.setContent(R.layout.yourLayoutWithListView);

来源

2011-11-22 20:04:12 kaspermoerch

你把你的com.tyczj.bowling/com.tyczj.bowling.Tabs活动清单文件？

来源

2011-11-22 19:54:44 PaulG

是的，它是在那里 – tyczj

可能是不正确的，但你错过了setContent？

super.onCreate(savedInstanceState); 
??? you must set content XML 
lv = getListView(); //NullPointerException

这就像使用TabActivity - 你可以调用getTabHost但只设置内容的XML布局定义后。尝试

super.onCreate(savedInstanceState); 
**this.setContent(R.layout.mylistviewlayout);** 
lv = getListView(); //NullPointerException

来源

2011-11-22 19:56:58

我想，但我仍然得到同样的事情 – tyczj

如果您使用的是ListFragment，你可能希望你的onCreate更改为：

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

然后

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

    lv = getListView(); // here it is available 
}

来源

2013-05-05 09:09:13

getListView（）上的空指针

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