Develop Reference

database operation in android loader

I'm using a LoaderManager, the onCreateLoader method creates a new CursorLoader.
#Override
public Loader<Cursor> onCreateLoader(int id, Bundle data) {
return new CursorLoader(context, CONTENT_URI, PROJECTION,
null, null, null);
}
Only after loading is finished in onLoadFinished() the UI is updated.
Every time I load the cusor I also need to do some database manipulation like building up a new sort index. This cannot be done asynchronously because the UI depends on this.
Is there a way to do such db operation within the loader? Or what is the best design for this problem?

As per your question you are loading your data in from database using loader and content provider
also you are working on sorting type of thing which can change the order of item in database...
So, the best way I suggest as per my experience in this type of application of do this of index sorting operation in UI only util user leave the screen...
So, In you activity of fragment override onStop method and update data indexes in database based on sorting priorities or numbers...
and after updating data to content provider just notify URI for change..
hope my point is clear to you..

Loaders were designed specifically with optimizing database access in mind. This operation does not care about updating the UI and hence has no interest in providing progress information. While it is possible (and I use this loosely), to update the UI from a loader, you should avoid this as the Loader is a wrong tool for this job. Forcing a Loader to provide progress information would break the paradigm. The Loader is expected to return only after the etire operation is complete. Instead, if you want to update the UI while doing the querying, then you should use an AsyncTask.
If you HAVE to use a Loader, then you can find a workaround here at Update progressbar from AsyncTaskLoader?. But again, since from your question, it looks like you are open to alternatives, use the AsyncTask if you need updates or you can stick to Java threads.

How to use LoaderManager.LoaderCallbacks and CursorLoader for ORMLite?

Recently I started using ORMLite for my application. Before I used to use 'ContentProvider' and implement LoaderManager.LoaderCallbacks<Cursor>. I would create CursorLoader and show the list to user when I have data.
How can I manage that cycle with ORMLite?
I want to create Cursor and get notified when Cursor is ready.
Thanks

Disable notifications on a ContentProvider URI

I'm looking for a way to suspend notifications on a given ContentProvider's Uri. The use case is:
An Activity is bound to a CursorAdapter through a CursorLoader.
A Service may do a lot of batch, single-row updates on a ContentProvider.
The CursorLoader will reload its content on every row update, as the ContentProvider notifies listeners by ContentResolver#notifyChange.
Since I cannot edit the ContentProvider, and I have no control over the batch queries execution, is there a way to suspend notifications on a Uri (in the executing Service) until all of the ContentProvider-managed queries have been executed? I need this in order to avoid the flickering caused by the continuous requerying of the CursorLoader.

You cannot disable this mechanism in your Service. But you should try to batch them by using ContentProviderOperations.
I've written an introductory post about ContentProviderOperations and two additional posts covering the methods withYieldAllowed() and withBackReference() respectively.
Especially the latter one should be of interest for what you've described here.
With ContentProviderOperations you can batch multiple updates and inserts. If you then call applyBatch() on your ContentResolver object the ContentProvider executes them all at once.
Now I've never used Nicolas Klein's generator but since he is a very, very proficient Android developer and works at Google, I bet that the generated code makes use of transactions and calls notifyChange() only once for the complete batch at the end.
Exactly what you need.

Can you substitute your own ContentResolver?
You may try extends ContentResolver with your own class then and you will may override method notifyChange and realize your logic there.

In your Content provider class, inside query() method before returning the cursor, just comment the code which looks something like this
cursor.setNotificationUri(getContext().getContentResolver(), uri);

android - CursorLoader & SQLite without Content Provider

I know this has been discussed yet I wanted to ask about the current state of the matter. Do i have to create a ContentProvider to use CursorLoader in connection with a sqlite database?
I found
CursorLoader usage without ContentProvider
Looks exactly what I was hoping for yet as Emmby commented
Users should be aware of one limitation, which is that it has no mechanism to refresh on data changes (as Loaders are supposed to do)
So another solution is mentioned
https://github.com/commonsguy/cwac-loaderex
yet again some drawback is pointed out
However, to make use of the automatic re-querying, you need to use the same loader for the UI as well as for the updates, limiting its usability for background services.
Of course when using LoaderManager we want to get all the benefits for which it was introduced. So my question is if there is a way to use LoaderManager in connection with a sqlite database without having to implement a content provider yet have all the benefits of it.
Thanks

The two implementations you mention in your post both offer all of the benefits of the CursorLoader except the ability to receive notifications when the underlying content changes.
I've been looking into this a lot recently and I can confidently tell you that the Android API currently does not provide a means of doing this with only a raw SQLiteDatabase (it only provides the ContentResolver#notifyChange() and Cursor#setNotificationUri() methods, which are used to notify all Cursors registered under a certain notification Uri).
That said, your options right now are to:
Implement an observer yourself that is capable of receiving notifications from the SQLiteDatabase when the content changes, and is somehow able to relay these notifications to all existing Loaders in your application. I wrote a pretty extensive blog post on how to implement Loaders that might come in handy if you wish to take on this challenge. Or...
Use Mark Murphy's LoaderEx library and only make database modifications using the AsyncTask operations his library provides. Note that the reason why his tasks refresh the Loader is because they call onContentChanged on the Loader immediately after the insertion/update/delete is performed, effectively telling the Loader that the content has changed and that it should refresh its data.
Just use a ContentProvider with a CursorLoader and you can use the ContentResolver#notifyChange() method to notify the CursorLoader that a content change has occurred.
I'm trying to figure out a better solution, and I'll report back in the future if I ever find/implement one, but for now these will have to do.

Here is my solution, in my onCreateLoader
{
Uri u = Uri.parse("content://what_string_you_want");
return new CursorLoader(this, yourURI, projection, null, null, null) {
private final ForceLoadContentObserver mObserver = new ForceLoadContentObserver();
#Override
public Cursor loadInBackground() {
Cursor c = YOUR_DATABASE.doYourQuery(...);
if (c != null) {
// Ensure the cursor window is filled
c.getCount();
c.registerContentObserver(mObserver);
}
c.setNotificationUri(getContext().getContentResolver(), getUri());
return c;
}
};
}
After the code that will change DB, add
getContentResolver().notifyChange(
Uri.parse("content://same_with_first_string"), null);

how about having a boolean in shared preferences as false .. updating the content when that boolean is true....
and when any of the operations which changes the underlying database .. that boolean will be set to true and as shared preferences you a changelistener you can recieve changes live directly after the relevant methods are called

Proper implementation of changing ListView data with CursorAdapter

I have a ListView populated via a CursorAdapter. I give my user the ability to alter the data in the list. For example, the user can mark a row as being unread (the data are messages).
Suppose my user marked a row unread. Would a proper implementation mark the row in the database as read and then requery the Cursor?

Would a proper implementation mark the row in the database as read and then requery the Cursor?
Yes, that's the right answer. The requery() will trigger an automatic update of your CursorAdapter, which will trigger an automatic update of the ListView, which will trigger an automatic smile from the user. :-)
UPDATE
The requery() method is deprecated. A better approach nowadays is to run a query to get a fresh Cursor, then use changeCursor() or swapCursor() on your CursorAdapter.

If the cursor is back by a ContentProvider and the ContentProvider issues correct notifications, the CursorAdapter will automatically refresh itself i.e. without the need to issue an explicit requery().