Thumbnails를 여러 번 가져온 후 NullPointerException이 표시되는 이유는 무엇입니까?

Question

MediaStore.Images.Thumbnails.getThumbnail을 사용하여 이미지 및 비디오 파일의 Thumbnails을 얻고 싶습니다.

폴더에 여러 파일이 있습니다. 다음 코드를 사용하여 이미지 및 비디오 파일 Thumbnails을 얻습니다.

다음 코드를 사용하여 이미지 및 비디오 파일의 Thumbnails을 얻을 수 있습니다.

String[] projection_image = { MediaStore.Images.Media.DATA, MediaStore.Images.Media._ID, }; 
      String[] projection_video = { MediaStore.Video.Media.DATA, MediaStore.Video.Media._ID, }; 

      File file = new File(viewTag.mFileNode.mName) ; 
      String tempfilePath = file.getPath(); 

      String whereClause_image = MediaStore.Images.Media.DATA + " = '" + tempfilePath + "'"; 
      String whereClause_video = MediaStore.Video.Media.DATA + " = '" + tempfilePath + "'"; 

      ContentResolver cr = getActivity().getContentResolver(); 
      Cursor image_cursor = cr.query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, projection_image, whereClause_image, null, null); 
      Cursor video_cursor = cr.query(MediaStore.Video.Media.EXTERNAL_CONTENT_URI, projection_video, whereClause_video, null, null); 

      if(image_cursor.moveToFirst()){ 
       long thumID = image_cursor.getLong(image_cursor.getColumnIndex("_ID")); 
       Bitmap bitmap_image = MediaStore.Images.Thumbnails.getThumbnail(getActivity().getContentResolver(), thumID, Images.Thumbnails.MICRO_KIND, null); 
       viewTag.mThumbnail.setImageBitmap(bitmap_image) ; 

      } 

      if(video_cursor.moveToFirst()){ 
       long thumID = video_cursor.getLong(video_cursor.getColumnIndex("_ID")); 
       Bitmap bitmap_video = MediaStore.Video.Thumbnails.getThumbnail(getActivity().getContentResolver(), thumID, Video.Thumbnails.MICRO_KIND, null); 
       viewTag.mThumbnail.setImageBitmap(bitmap_video) ; 

      } 

하지만이 페이지 몇 시간을 다시로드 할 때, 그것은 오류 로그이 (가) 다음과 같이이다 java.lang.NullPointerException

보여

이

D/AndroidRuntime(3014): Shutting down VM 
W/dalvikvm(3014): threadid=1: thread exiting with uncaught exception (group=0x410e2450) 
E/AndroidRuntime(3014): FATAL EXCEPTION: main 
E/AndroidRuntime(3014): java.lang.NullPointerException 
E/AndroidRuntime(3014): at tw.com.a_i_t.IPCamViewer.FileBrowser.LocalFileBrowserFragment$LocalFileListAdapter.getView(LocalFileBrowserFragment.java:950) 
E/AndroidRuntime(3014): at android.widget.AbsListView.obtainView(AbsListView.java:2255) 
E/AndroidRuntime(3014): at android.widget.GridView.onMeasure(GridView.java:1045) 
E/AndroidRuntime(3014): at android.view.View.measure(View.java:15367) 
E/AndroidRuntime(3014): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4924) 
E/AndroidRuntime(3014): at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1420) 
E/AndroidRuntime(3014): at android.widget.LinearLayout.measureVertical(LinearLayout.java:697) 
E/AndroidRuntime(3014): at android.widget.LinearLayout.onMeasure(LinearLayout.java:578) 
E/AndroidRuntime(3014): at android.view.View.measure(View.java:15367) 
E/AndroidRuntime(3014): at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:622) 
E/AndroidRuntime(3014): at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:404) 
E/AndroidRuntime(3014): at android.view.View.measure(View.java:15367) 
E/AndroidRuntime(3014): at android.widget.RelativeLayout.measureChild(RelativeLayout.java:607) 
E/AndroidRuntime(3014): at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:420) 
E/AndroidRuntime(3014): at android.view.View.measure(View.java:15367) 
E/AndroidRuntime(3014): at android.widget.RelativeLayout.measureChild(RelativeLayout.java:607) 
E/AndroidRuntime(3014): at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:420) 
E/AndroidRuntime(3014): at android.view.View.measure(View.java:15367) 
E/AndroidRuntime(3014): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4924) 
E/AndroidRuntime(3014): at android.widget.FrameLayout.onMeasure(FrameLayout.java:314) 
E/AndroidRuntime(3014): at android.view.View.measure(View.java:15367) 
E/AndroidRuntime(3014): at android.widget.LinearLayout.measureVertical(LinearLayout.java:849) 
E/AndroidRuntime(3014): at android.widget.LinearLayout.onMeasure(LinearLayout.java:578) 
E/AndroidRuntime(3014): at android.view.View.measure(View.java:15367) 
E/AndroidRuntime(3014): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4924) 
E/AndroidRuntime(3014): at android.widget.FrameLayout.onMeasure(FrameLayout.java:314) 
E/AndroidRuntime(3014): at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2154) 
E/AndroidRuntime(3014): at android.view.View.measure(View.java:15367) 
E/AndroidRuntime(3014): at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1858) 
E/AndroidRuntime(3014): at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1106) 
E/AndroidRuntime(3014): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1279) 
E/AndroidRuntime(3014): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1004) 
E/AndroidRuntime(3014): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4223) 
E/AndroidRuntime(3014): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:725) 
E/AndroidRuntime(3014): at android.view.Choreographer.doCallbacks(Choreographer.java:555) 
E/AndroidRuntime(3014): at android.view.Choreographer.doFrame(Choreographer.java:525) 
E/AndroidRuntime(3014): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:711) 
E/AndroidRuntime(3014): at android.os.Handler.handleCallback(Handler.java:615) 
E/AndroidRuntime(3014): at android.os.Handler.dispatchMessage(Handler.java:92) 
E/AndroidRuntime(3014): at android.os.Looper.loop(Looper.java:213) 
E/AndroidRuntime(3014): at android.app.ActivityThread.main(ActivityThread.java:4786) 
E/AndroidRuntime(3014): at java.lang.reflect.Method.invokeNative(Native Mehod) 
E/AndroidRuntime(3014): at java.lang.reflect.Method.invoke(Method.java:511) 
E/AndroidRuntime(3014): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789) 
E/AndroidRuntime(3014): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:556) 
E/AndroidRuntime(3014): at dalvik.system.NativeStart.main(Native Method) 
W/ActivityManager( 610): Force finishing activity tw.com.a_i_t.IPCamViewer/.MainActivity 

가 (LocalFileBrowserFragment.java:950)에서, 그것은 if(video_cursor.moveToFirst()){입니다 코드의 오류가있다

이미 이미지 및 동영상 파일의 미리보기 이미지를 성공적으로 가져 왔습니다.

이 페이지를 여러 번 다시로드하면 왜 이런 문제가 발생합니까?

Answer 1

다음 코드를 사용하여 문제를 해결합니다.

try { 

       if(image_cursor.moveToFirst()){ 
        long thumID = image_cursor.getLong(image_cursor.getColumnIndex("_ID")); 
        Bitmap bitmap_image = MediaStore.Images.Thumbnails.getThumbnail(getActivity().getContentResolver(), thumID, Images.Thumbnails.MICRO_KIND, null); 
        viewTag.mThumbnail.setImageBitmap(bitmap_image) ; 

       } 

       if(video_cursor.moveToFirst()){ 
        long thumID = video_cursor.getLong(video_cursor.getColumnIndex("_ID")); 
        Bitmap bitmap_video = MediaStore.Video.Thumbnails.getThumbnail(getActivity().getContentResolver(), thumID, Video.Thumbnails.MICRO_KIND, null); 
        viewTag.mThumbnail.setImageBitmap(bitmap_video) ;    
       } 

      } catch (NullPointerException e) { 
       // TODO: handle exception 
       Log.i(TAG, "cursor---NullPointerException"); 

       image_cursor = cr.query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, projection_image, whereClause_image, null, null); 
       video_cursor = cr.query(MediaStore.Video.Media.EXTERNAL_CONTENT_URI, projection_video, whereClause_video, null, null); 

      } finally{ 
       image_cursor.close(); 
       video_cursor.close(); 
      }