Question

This is keeping me sleepless…
I’m creating a slideshow kind of app. Let’s say the package name is com.myapp.slideshow
User can create a new slideshow filled with pictures previously stored in the SD card app’s private folder (something like root/Android/data/com.myapp.slideshow/files/immagini/)

Because of this, i cannot use the built in gallery through ACTION_GET_CONTENT and therefore i have created my own gallery activity class.

So to recap i have SlideshowEditor.java where user click on a button to access the IMGALLERYactivity.java where they can click pich a picture from the gallery slide object and allegedly return back to SlideshowEditor.java with the picked picture Uri.

The problem with my code is that when i run the app (i test straight on device via eclipse) i don’t seem to get the Uri back and get a nullpointer exception which stops the app.

Here is the code i’m using:

SlideshowEditor.java

       // set IDs for each type of media result
   private static final int PICTURE_ID = 1;
   private static final int MUSIC_ID = 2;
   private static final int VIDEO_ID = 3;       
   private static final int TAKE_PICTURE_ID = 4;

   // called when an Activity launched from this Activity returns
   @Override
   protected final void onActivityResult(int requestCode, int resultCode, 
      Intent data)
   {
      if (resultCode == RESULT_OK) // if there was no error
      {
         Uri selectedUri = data.getData(); 

         // if the Activity returns an image
         if (requestCode == PICTURE_ID || 
            requestCode == TAKE_PICTURE_ID || requestCode == VIDEO_ID )
         {
            // determine media type
            MediaItem.MediaType type = (requestCode == VIDEO_ID ?     
               MediaItem.MediaType.VIDEO : MediaItem.MediaType.IMAGE);

            // add new MediaItem to the slideshow
            slideshow.addMediaItem(type, selectedUri.toString());

            // refresh the ListView 
            slideshowEditorAdapter.notifyDataSetChanged();
         } // end if
         else if (requestCode == MUSIC_ID) // Activity returns music
            slideshow.setMusicPath(selectedUri.toString());
      } // end if
   } // end method onActivityResult

   // called when the user touches the "Done" Button
   private OnClickListener doneButtonListener = new OnClickListener()
   {
      // return to the previous Activity
      @Override
      public void onClick(View v)
      {
         finish();
      } // end method onClick
   }; // end OnClickListener doneButtonListener

   // called when the user touches the "Add Picture" Button
   private OnClickListener addPictureButtonListener = new OnClickListener()
   {
      // launch image choosing activity
      @Override
      public void onClick(View v)
      {

         Intent intent = new Intent(SlideshowEditor.this, IMGALLERYactivity.class);
////         String imgfolder = (Environment.getExternalStorageDirectory().getAbsolutePath() + File.separator + "Android" + File.separator + "data" + File.separator + "com.myapp.slideshow" + File.separator + "files" + File.separator + "immagini" + File.separator).toLowerCase();
       //  Uri startDir = Uri.fromFile(new File("Environment.getExternalStorageDirectory().getAbsolutePath()"));
////         intent.setDataAndType(Uri.parse(imgfolder), "image/*");
         ///intent.setType("image/*");
         ///intent.Output();
         ////startActivity(intent);
         startActivityForResult(intent, PICTURE_ID);
      } // end method onClick
   }; // end OnClickListener addPictureButtonListener

IMGALLERYactivity.java

public class IMGALLERYactivity extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.imgallery);

   Gallery g = (Gallery) findViewById(R.id.gallery);    g.setAdapter(new ImageAdapter(this, ReadSDCard()));

   g.setOnItemClickListener(new OnItemClickListener() {
       public void onItemClick(AdapterView<?> parent,
         View v, int position, long id) {
           Toast.makeText(IMGALLERYactivity.this, "" + position, Toast.LENGTH_SHORT).show();

           Intent i = new Intent(IMGALLERYactivity.this, SlideshowEditor.class);                 
           i.putExtra("PICTURE_ID", position);                 
           setResult(Activity.RESULT_OK, i);
           finish();           
    //     Intent resultIntent = new Intent(); 
    //     // TODO Add extras or a data URI to this intent as appropriate. 
    //     setResult(Activity.RESULT_OK, resultIntent); 
    //     finish();           

       }    }); }

private List<String> ReadSDCard() { List<String> tFileList = new ArrayList<String>();

//It have to be matched with the directory in SDCard

//File folder = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + File.separator + "Android" + File.separator + "data" + File.separator
+ "com.deepsabrina.sabrinadeep" + File.separator + "files" + File.separator + "immagini");

File f = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + File.separator + "Android" + File.separator + "data" + File.separator
+ "com.deepsabrina.sabrinadeep" + File.separator + "files" + File.separator + "immagini" + File.separator);

File[] files=f.listFiles();

for(int i=0; i<files.length; i++) {  File file = files[i];  /*It's assumed that all file in the path    are in supported type*/  tFileList.add(file.getPath()); }

return tFileList; }

public class ImageAdapter extends BaseAdapter {    int mGalleryItemBackground;    private Context mContext;    private List<String> FileList;

   public ImageAdapter(Context c, List<String> fList) {
       mContext = c;
       FileList = fList;
       TypedArray a = mContext.obtainStyledAttributes(R.styleable.HelloGallery);
       mGalleryItemBackground = a.getResourceId(
       R.styleable.HelloGallery_android_galleryItemBackground,0);
       a.recycle();    }

   public int getCount() {
       return FileList.size();    }

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

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

   public View getView(int position, View convertView,
     ViewGroup parent) {
       ImageView i = new ImageView(mContext);

       Bitmap bm = BitmapFactory.decodeFile(
         FileList.get(position).toString());
       i.setImageBitmap(bm);

       i.setLayoutParams(new Gallery.LayoutParams(150, 100));
       i.setScaleType(ImageView.ScaleType.FIT_XY);
       i.setBackgroundResource(mGalleryItemBackground);

       return i;    } }

public TypedArray obtainStyledAttributes(int theme) {   // TODO Auto-generated method stub  return null; } }

What am i doing wrong?
Any help would be really appreciated, possibly with code corrections as i have just started familiarizing with Android although i have a medium knowledge of java.

---

EDIT:

Thanks Brian! I was able to get the path of the selected item based on position, setting the get item() as you suggested and then creating the var like: String pippo = parent.getItemAtPosition(position).toString(); At least i’ve moved one step forward…However i’m still not able to pass it to the SlideshowEditor.class. This is what i have put on the IMGALLERYactivity class on the onitemclicklistener:

public void onItemClick(AdapterView<?> parent,
     View v, int position, long id) {
       String pippo = parent.getItemAtPosition(position).toString();


      Intent data = new Intent(IMGALLERYactivity.this, SlideshowEditor.class);                 
      data.putExtra("PICTURE_ID", pippo);                 
      setResult(RESULT_OK, data);
      finish();            


   } 

On the SlideshowEditor.class i have

 protected final void onActivityResult(int requestCode, int resultCode, 
      Intent data)
   {

      if (resultCode == RESULT_OK) // if there was no error
      {

          Uri selectedUri = Uri.parse(data.getDataString());         
          //Uri selectedUri = data.getData(); 

         // if the Activity returns an image
         if (requestCode == PICTURE_ID || 
            requestCode == TAKE_PICTURE_ID || requestCode == VIDEO_ID )
         {
            // determine media type
            MediaItem.MediaType type = (requestCode == VIDEO_ID ?     
               MediaItem.MediaType.VIDEO : MediaItem.MediaType.IMAGE);

            // add new MediaItem to the slideshow
            slideshow.addMediaItem(type, selectedUri.toString());

            // refresh the ListView 
            slideshowEditorAdapter.notifyDataSetChanged();
         } // end if
         else if (requestCode == MUSIC_ID) // Activity returns music
            slideshow.setMusicPath(selectedUri.toString());
      } // end if
   } // end method onActivityResult  

The whole process is started with

Intent intent = new Intent(SlideshowEditor.this, IMGALLERYactivity.class);

         startActivityForResult(intent,PICTURE_ID);                                                                                   

I keep getting nullpointerexception. I’ve tried to use eclipse debug and my understanding is that that nullpointerexception is shot at the IMGALLERYactivity when i create the intent, but i wouldn’t bet on it because eclipse debugging seems very confusing to me…however i toggled a breakpoint at the onactivityresult on the SlideshowEditor.class and it looks like the nullpointer exception is shot before it reaches that point. I know you don’t do private consulting, but i’m banging my head on this since 3 days now and any help would really help me out, before i go completely insane lol

This is the logcat results:

02-06 19:26:40.080: E/AndroidRuntime(10661): FATAL EXCEPTION: main
02-06 19:26:40.080: E/AndroidRuntime(10661):
java.lang.RuntimeException: Failure delivering result
ResultInfo{who=null, request=1, result=-1, data=Intent {
cmp=com.deitel.enhancedslideshow/.SlideshowEditor (has extras) }} to
activity
{com.deitel.enhancedslideshow/com.deitel.enhancedslideshow.SlideshowEditor}:
java.lang.NullPointerException: uriString 02-06 19:26:40.080:
E/AndroidRuntime(10661): at
android.app.ActivityThread.deliverResults(ActivityThread.java:2918)
02-06 19:26:40.080: E/AndroidRuntime(10661): at
android.app.ActivityThread.handleSendResult(ActivityThread.java:2970)
02-06 19:26:40.080: E/AndroidRuntime(10661): at
android.app.ActivityThread.access$2000(ActivityThread.java:132) 02-06
19:26:40.080: E/AndroidRuntime(10661): at
android.app.ActivityThread$H.handleMessage(ActivityThread.java:1068)
02-06 19:26:40.080: E/AndroidRuntime(10661): at
android.os.Handler.dispatchMessage(Handler.java:99) 02-06
19:26:40.080: E/AndroidRuntime(10661): at
android.os.Looper.loop(Looper.java:150) 02-06 19:26:40.080:
E/AndroidRuntime(10661): at
android.app.ActivityThread.main(ActivityThread.java:4277) 02-06
19:26:40.080: E/AndroidRuntime(10661): at
java.lang.reflect.Method.invokeNative(Native Method) 02-06
19:26:40.080: E/AndroidRuntime(10661): at
java.lang.reflect.Method.invoke(Method.java:507) 02-06 19:26:40.080:
E/AndroidRuntime(10661): at
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
02-06 19:26:40.080: E/AndroidRuntime(10661): at
com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 02-06
19:26:40.080: E/AndroidRuntime(10661): at
dalvik.system.NativeStart.main(Native Method) 02-06 19:26:40.080:
E/AndroidRuntime(10661): Caused by: java.lang.NullPointerException:
uriString 02-06 19:26:40.080: E/AndroidRuntime(10661): at
android.net.Uri$StringUri.(Uri.java:420) 02-06 19:26:40.080:
E/AndroidRuntime(10661): at
android.net.Uri$StringUri.(Uri.java:410) 02-06 19:26:40.080:
E/AndroidRuntime(10661): at android.net.Uri.parse(Uri.java:382) 02-06
19:26:40.080: E/AndroidRuntime(10661): at
com.deitel.enhancedslideshow.SlideshowEditor.onActivityResult(SlideshowEditor.java:87)
02-06 19:26:40.080: E/AndroidRuntime(10661): at
android.app.Activity.dispatchActivityResult(Activity.java:4108) 02-06
19:26:40.080: E/AndroidRuntime(10661): at
android.app.ActivityThread.deliverResults(ActivityThread.java:2914)

Answer 1

So the only thing you’re adding to your Intent is this:

Intent i = new Intent(IMGALLERYactivity.this, SlideshowEditor.class);                 
i.putExtra("PICTURE_ID", position);                 

But then you’re trying to get something out of the resulting Intent in your onActivityResult() method that you never put in:

Uri selectedUri = data.getData();

The only thing you could pull out of there is this:

int position = data.getIntExtra("PICTURE_ID", 0);

Which… probably wouldn’t do a lot of good. You could put the URI in as an extra.

i.putExtra("PICTURE_URI", uriOfSelectedItem);

And pull that out on the other side in onActivityResult().