Android-发生崩溃，但堆栈跟踪未说明发生的位置

Question

I have a null pointer exception somewhere, but I am not sure where. All I have is this error:

java.lang.NullPointerException
        at android.widget.ArrayAdapter.getCount(ArrayAdapter.java:330)
        at android.widget.AdapterView.checkFocus(AdapterView.java:700)
        at android.widget.AdapterView$AdapterDataSetObserver.onInvalidated(AdapterView.java:823)
        at android.widget.AbsListView$AdapterDataSetObserver.onInvalidated(AbsListView.java:5738)
        at android.database.DataSetObservable.notifyInvalidated(DataSetObservable.java:47)
        at android.widget.BaseAdapter.notifyDataSetInvalidated(BaseAdapter.java:59)
        at android.widget.ArrayAdapter$ArrayFilter.publishResults(ArrayAdapter.java:513)
        at android.widget.Filter$ResultsHandler.handleMessage(Filter.java:282)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:137)
        at android.app.ActivityThread.main(ActivityThread.java:4697)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:511)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:787)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:554)
        at dalvik.system.NativeStart.main(Native Method)

Would anyone have any ideas for how to debug this? I have not been able to reproduce it. It just sometimes happens and shows up in my crash logs.

Thanks!

Answer 1

Here's the code for ArrayAdapter: https://github.com/android/platform_frameworks_base/blob/master/core/java/android/widget/ArrayAdapter.java .

Assuming this is the right version, an NPE on line 330 would be caused if the adapter's dataset (ie the backing list or array) is null.

Hope that helps.