java.lang.NullPointerException：uriString

Question

私は初心者で、ビデオプレーヤーを作成しようとしています。ヌルポインタの例外が発生しています.SOに関するすべての質問を読んで、それに関連するgoogleを検索して読んでいます。 thumbpathはこの例外の唯一の理由かもしれませんが、nullには見えません。誰もそれで私を助けることができますか？おかげ

SDVideos.java

package com.example.dell_1.myapp3; 

import android.app.Activity; 
import android.content.Context; 
import android.database.Cursor; 
import android.net.Uri; 
import android.os.Bundle; 
import android.provider.MediaStore; 
import android.util.Log; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.AdapterView; 
import android.widget.BaseAdapter; 
import android.widget.ImageView; 
import android.widget.ListView; 
import android.widget.TextView; 

public class SDVideos extends Activity 
{ 
    private Cursor videoCursor; 
    private int videoColumnIndex; 
    ListView videolist; 
    int count; 
    String thumbPath; 

    String[] thumbColumns = { MediaStore.Video.Thumbnails.DATA,MediaStore.Video.Thumbnails.VIDEO_ID }; 
    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) 
    { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_sdvideos); 
     initialization(); 
    } 

    private void initialization() 
    { 
     System.gc(); 
     String[] videoProjection = { MediaStore.Video.Media._ID,MediaStore.Video.Media.DATA, 
       MediaStore.Video.Media.DISPLAY_NAME,MediaStore.Video.Media.SIZE }; 
     videoCursor =getContentResolver().query(MediaStore.Video.Media.EXTERNAL_CONTENT_URI,videoProjection, null, null, null); 
     count = videoCursor.getCount(); 
     videolist = (ListView) findViewById(R.id.PhoneVideoList); 

     videolist.setAdapter(new VideoListAdapter(this.getApplicationContext())); 
     videolist.setOnItemClickListener(videogridlistener); 
    } 

    private AdapterView.OnItemClickListener videogridlistener = new AdapterView.OnItemClickListener() { 
     public void onItemClick(AdapterView parent, View v, int position, long id) 
     { 
      videoColumnIndex = videoCursor.getColumnIndexOrThrow(MediaStore.Video.Media.DATA); 
      videoCursor.moveToPosition(position); 
      String filename = videoCursor.getString(videoColumnIndex); 
      Log.i("FileName: ", filename); 
//Intent intent = new Intent(VideoActivity.this, ViewVideo.class); 
//intent.putExtra("videofilename", filename); 
//startActivity(intent); 
     }}; 

    public class VideoListAdapter extends BaseAdapter 
    { 
     private Context vContext; 

     public VideoListAdapter(Context c) 
     { 
      vContext = c; 
     } 

     public int getCount() 
     { 
      return videoCursor.getCount(); 
     } 

     public Object getItem(int position) 
     { 
      return position; 
     } 

     public long getItemId(int position) 
     { 
      return position; 
     } 

     public View getView(int position, View convertView, ViewGroup parent) 
     { 
      View listItemRow; 
      listItemRow = LayoutInflater.from(vContext).inflate(R.layout.listitem, parent, false); 

      TextView txtTitle = (TextView)listItemRow.findViewById(R.id.txtTitle); 
      TextView txtSize = (TextView)listItemRow.findViewById(R.id.txtSize); 
      ImageView thumbImage = (ImageView)listItemRow.findViewById(R.id.imgIcon); 

      videoColumnIndex = videoCursor.getColumnIndexOrThrow(MediaStore.Video.Media.DISPLAY_NAME); 
      videoCursor.moveToPosition(position); 
      txtTitle.setText(videoCursor.getString(videoColumnIndex)); 

      videoColumnIndex = videoCursor.getColumnIndexOrThrow(MediaStore.Video.Media.SIZE); 
      videoCursor.moveToPosition(position); 
      txtSize.setText(" Size(KB):" + videoCursor.getString(videoColumnIndex)); 

      int videoId = videoCursor.getInt(videoCursor.getColumnIndexOrThrow(MediaStore.Video.Media._ID)); 
      Cursor videoThumbnailCursor =getContentResolver().query(MediaStore.Video.Thumbnails.EXTERNAL_CONTENT_URI, 
        thumbColumns, MediaStore.Video.Thumbnails.VIDEO_ID+ "=" + videoId, null, null); 

      if (videoThumbnailCursor.moveToFirst()) 
      { 
       thumbPath = videoThumbnailCursor.getString(videoThumbnailCursor.getColumnIndex(MediaStore.Video.Thumbnails.DATA)); 
       Log.i("ThumbPath: ",thumbPath); 
      } 
      thumbImage.setImageURI(Uri.parse(thumbPath)); 
      return listItemRow; 
     } 
    } 
} 

XMLファイル：

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
     android:orientation="vertical" 
     android:layout_width="fill_parent" 
     android:layout_height="fill_parent"> 
    <ListView 
     android:id="@+id/PhoneVideoList" 
     android:layout_width="fill_parent" 
     android:layout_height="fill_parent" 
     android:divider="#242424" 
     android:dividerHeight="1dp"/> 
    </LinearLayout> 

LOGCAT：

08-05 17:29:17.109 17708-17708/com.example.dell_1.myapp3 E/AndroidRuntime: FATAL EXCEPTION: main 
     Process: com.example.dell_1.myapp3, PID: 17708 
     java.lang.NullPointerException: uriString 
     at android.net.Uri$StringUri.<init>(Uri.java:475) 
    at android.net.Uri$StringUri.<init>(Uri.java) 
    at android.net.Uri.parse(Uri.java:437) 
    at com.example.dell_1.myapp3.SDVideos$VideoListAdapter.getView(SDVideos.java:112) 
    at android.widget.AbsListView.obtainView(AbsListView.java:2367) 
    at android.widget.ListView.makeAndAddView(ListView.java:1972) 
    at android.widget.ListView.fillDown(ListView.java:704) 
    at android.widget.ListView.fillFromTop(ListView.java:765) 
    at android.widget.ListView.layoutChildren(ListView.java:1744) 
    at android.widget.AbsListView.onLayout(AbsListView.java:2161) 
    at android.view.View.layout(View.java:17523) 
    at android.view.ViewGroup.layout(ViewGroup.java:5618) 
    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1741) 
    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1585) 
    at android.widget.LinearLayout.onLayout(LinearLayout.java:1494) 
    at android.view.View.layout(View.java:17523) 
    at android.view.ViewGroup.layout(ViewGroup.java:5618) 
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323) 
    at android.widget.FrameLayout.onLayout(FrameLayout.java:261) 
    at android.view.View.layout(View.java:17523) 
    at android.view.ViewGroup.layout(ViewGroup.java:5618) 
    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1741) 
    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1585) 
    at android.widget.LinearLayout.onLayout(LinearLayout.java:1494) 
    at android.view.View.layout(View.java:17523) 
    at android.view.ViewGroup.layout(ViewGroup.java:5618) 
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323) 
    at android.widget.FrameLayout.onLayout(FrameLayout.java:261) 
    at com.android.internal.policy.DecorView.onLayout(DecorView.java:724) 
    at android.view.View.layout(View.java:17523) 
    at android.view.ViewGroup.layout(ViewGroup.java:5618) 
    at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2374) 
    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2101) 
    at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1278) 
    at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6357) 
    at android.view.Choreographer$CallbackRecord.run(Choreographer.java:871) 
    at android.view.Choreographer.doCallbacks(Choreographer.java:683) 
    at android.view.Choreographer.doFrame(Choreographer.java:619) 
    at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:857) 
    at android.os.Handler.handleCallback(Handler.java:751) 
    at android.os.Handler.dispatchMessage(Handler.java:95) 
    at android.os.Looper.loop(Looper.java:154) 
    at android.app.ActivityThread.main(ActivityThread.java:6077) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755) 

Answer 1

私は任意のRを参照してくださいドントthumbPathがSDVideosのフィールドである必要がある理由は、VideoListAdapter.getView内でのみ使用されます。変数としてthumbPathを動かすの

更新されたコードは、次のようになります。

int videoId = videoCursor.getInt(videoCursor.getColumnIndexOrThrow(MediaStore.Video.Media._ID)); 
     Cursor videoThumbnailCursor =getContentResolver().query(MediaStore.Video.Thumbnails.EXTERNAL_CONTENT_URI, 
       thumbColumns, MediaStore.Video.Thumbnails.VIDEO_ID+ "=" + videoId, null, null); 

     if (videoThumbnailCursor.moveToFirst()) 
     { 
      String thumbPath = videoThumbnailCursor.getString(videoThumbnailCursor.getColumnIndex(MediaStore.Video.Thumbnails.DATA)); 
      Log.i("ThumbPath: ",thumbPath); 
      thumbImage.setImageURI(Uri.parse(thumbPath)); 
     } 

     return listItemRow; 

thumbPathのみカーソルが任意のデータを持っている場合、あなたはあなたの場合は内側にsetImageURIを移動することができ取り込まれますので。

このコードはNullPointerExceptionを解決しますが、おそらくthumbImageに画像が表示されません。

ここで、videoThumbnailCursorがデータを返さない理由を調べる必要があります。理由を見つけたら、質問を更新してください。