CursorLoader does not update after changing data

Question

I created a small application trying to understand the functionality of the LoaderManager and CursorLoader .

I implemented LoaderCallbacks<Cursor> in my FragmentActivity class and everything works fine, except for the fact that when I update my data using the ContentResolver.update() or ContentResolver.insert() onLoadFinished() , onLoadFinished() not called and as a result my data is not updated.

I have a custom ContentProvider, and I am wondering if there is no problem in my ContentProvider not notifying that the data has changed or something else.

Answer 1

Did you call setNotificationUri(ContentResolver cr, Uri uri) in Cursor before returning it to ContentProvider.query() ?

And you called getContext().getContentResolver().notifyChange(uri, null) in the "insert" method of your ContentProvider ?

EDIT:

To get the ContentResolver call getContext().getContentResolver() in the ContentProvider .

Answer 2

Also check that you are calling cursor.close () somewhere, because in this case you will unregister the contents registered by CursorLoader. And closing the cursor is controlled by CursorLoader.

Answer 3

The accepted answer was a little difficult to understand, so I am writing an answer to make it easy for other developers.

• Go to the class where you extended ContentProvider

• Find the query () method that has the following syntax

  public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder)

• Write this line where you return the cursor

  cursor.setNotificationUri(getContext().getContentResolver(), uri); return cursor;

At the end, my query method is as follows:

 @Nullable @Override public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) { Cursor cursor; cursor = noticeDbHelper.getReadableDatabase().query( NoticeContract.NoticeTable.TABLE_NAME, projection, selection, selectionArgs, null, null, sortOrder ); //This line will let CursorLoader know about any data change on "uri" , So that data will be reloaded to CursorLoader cursor.setNotificationUri(getContext().getContentResolver(), uri); return cursor; }` 

Answer 4

Can someone explain to me a simple way to understand how this next method works

 cursor.setNotificationUri(getContext().getContentResolver(), uri); getContext().getContentResolver().notifyChange(uri, null) 

and what is the relationship between them? thank