NPE在DaysAdapter.getView（DaysFragment.java:117）

直覺上我知道我們爲什麼會得到一個NPE異常，但在這種情況下我找不到原因。也許這只是一天結束。我在這行NPE在DaysAdapter.getView（DaysFragment.java:117）

viewHolder.dayCaption.setText(storage.getDayName(i));

越來越NPE我用這個代碼登錄：

Log.d("MTEST","viewHolder="+viewHolder+"\nviewHolder.dayCaption="+viewHolder.dayCaption+"\nstorage.getDayName(i)="+storage.getDayName(i));

，並得到這個值：

viewH[email protected]423df950 
viewHolder.dayCaption= [email protected] 

storage.getDayName(i)=Monday

這個充滿適配器

private class DaysAdapter extends BaseAdapter implements AdapterView.OnItemClickListener{ 

    @Override 
    public int getCount() { 
     return dayEnabled.length; 
    } 

    @Override 
    public Object getItem(int i) { 
     return null; 
    } 

    @Override 
    public long getItemId(int i) { 
     return i; 
    } 
    private class ViewHolder { 
     TextView dayCaption; 
     CheckBox dayCheck; 
    } 
    @Override 
    public View getView(int i, View view, ViewGroup viewGroup) { 
     ViewHolder viewHolder; 

     if (view == null) { 
      view = getActivity().getLayoutInflater().inflate(R.layout.day_list_item, viewGroup, false); 
      viewHolder = new ViewHolder(); 
      viewHolder.dayCaption = (TextView) view.findViewById(R.id.day_caption); 
      viewHolder.dayCheck = (CheckBox) view.findViewById(R.id.day_check);     
     } else { 
      viewHolder = (ViewHolder) view.getTag(); 
     } 
     storage = Storage.getInstance(); 
//   Log.d("MTEST","viewHolder="+viewHolder+"\nviewHolder.dayCaption= "+viewHolder.dayCaption+"\nstorage.getDayName(i)="+storage.getDayName(i)); 
      viewHolder.dayCaption.setText(storage.getDayName(i)); 
      viewHolder.dayCheck.setTag(i); 
      viewHolder.dayCheck.setChecked(dayEnabled[i]); 
      viewHolder.dayCheck.setOnCheckedChangeListener(checkedChangeListener); 

     return view; 
    } 

    @Override 
    public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) { 
     activity.showDayTime(i); 
    } 




}

實際日誌爲

10-01 17:18:19.176: E/AndroidRuntime(4455): FATAL EXCEPTION: main 
10-01 17:18:19.176: E/AndroidRuntime(4455): java.lang.NullPointerException 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at com.revolage.eyespause.fragments.DaysFragment$DaysAdapter.getView(DaysFragment.java:120) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.widget.AbsListView.obtainView(AbsListView.java:2255) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.widget.ListView.measureHeightOfChildren(ListView.java:1269) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.widget.ListView.onMeasure(ListView.java:1181) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.view.View.measure(View.java:15323) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4924) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1421) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.widget.LinearLayout.measureVertical(LinearLayout.java:698) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.widget.LinearLayout.onMeasure(LinearLayout.java:579) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.view.View.measure(View.java:15323) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4924) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.widget.FrameLayout.onMeasure(FrameLayout.java:315) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.view.View.measure(View.java:15323) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4924) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.widget.FrameLayout.onMeasure(FrameLayout.java:315) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.view.View.measure(View.java:15323) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:622) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:404) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.view.View.measure(View.java:15323) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4924) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.widget.FrameLayout.onMeasure(FrameLayout.java:315) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.view.View.measure(View.java:15323) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.widget.LinearLayout.measureVertical(LinearLayout.java:850) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.widget.LinearLayout.onMeasure(LinearLayout.java:579) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.view.View.measure(View.java:15323) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4924) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.widget.FrameLayout.onMeasure(FrameLayout.java:315) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2155) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.view.View.measure(View.java:15323) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1854) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1102) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1275) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1000) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4218) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.view.Choreographer$CallbackRecord.run(Choreographer.java:725) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.view.Choreographer.doCallbacks(Choreographer.java:555) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.view.Choreographer.doFrame(Choreographer.java:525) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:711) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.os.Handler.handleCallback(Handler.java:615) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.os.Handler.dispatchMessage(Handler.java:92) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.os.Looper.loop(Looper.java:137) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at android.app.ActivityThread.main(ActivityThread.java:4744) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at java.lang.reflect.Method.invokeNative(Native Method) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at java.lang.reflect.Method.invoke(Method.java:511) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 
10-01 17:18:19.176: E/AndroidRuntime(4455):  at dalvik.system.NativeStart.main(Native Method)

來源

2014-10-01 mdzht

你介意展示一些更多的代碼嗎？從你的日誌來看，這看起來可能會起作用。我懷疑這個問題有點深刻。 – erad 2014-10-01 10:28:54

我已添加適配器 – mdzht 2014-10-01 13:38:19

您是否也可以顯示實際的錯誤日誌？ – erad 2014-10-01 14:39:02

您忘記了setTag()將視圖保持器存儲在視圖中。在回收視圖中，與getTag()一起檢索的持有者將爲空。

在if (view == null)塊的末尾添加

view.setTag(viewHolder);

。

來源

2014-10-01 15:49:27 laalto

NPE在DaysAdapter.getView（DaysFragment.java:117）

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