I can't figure out why I should use a ContentProvider with the setting "android:exported=false" in the AndroidManifest.xml. Aren't ContentProviders created to share data between multiple applications? In this way, I am restricting data sharing only to my application and not to external applications. But at this point I can simply use a database in SQLite (maybe with SQLiteOpenHelper).
In the case where I need to create a pre-populated database by loading data from a Rest API, but at the same time I do not need to share my data to other applications, should I create a ContentProvider with the setting "android:exported=false" using the ContentProviderOperation and ContentProviderOperation.Builder Classes (I have seen that these two Classes are used for massive data insertion) ? Or should I create a database in SQLite and insert the data using the INSERT command ?
Thank you!
I'm kinda new in android development and I am little confused about content providers. Content providers are used to share your data with other application legally, but is it correct to use it for retrieving your data from SQLite databaseand display it in, for instance listView? What is better solution for displaying data from db?
Thanks
Yes it is legit using the ContentProvider to retrieve data from a SQLite database while its perfectly fine creating an Handler to handle the SQLiteOpenHelper and just using it.
Its all depends on your app's needs,
Me individually for my own app if no need for sharing data wouldn't use a content provider.
if you don't need to share the data base from your app it's not necessary to use a Content Provider
I am creating app that should have offline mode, so previously downloaded data should stored somewhere, the most common way is to store data in SQLite database.
Mostly SQLite database is used with Content Provider in android. I have clear understanding what is the purpose of content provider (to share data between different apps), but in my case application will never need to share the data with other apps in the system.
Content provider has the similar interface as HTTP request (GET,POST,PUT,DELETE).
My idea is to create facade class which can be used like this getAllLatestNews(); firstly it will try to get latest data from the internet, if it fails - data from database will be used and if request is successful it also will save retrieved data to the database. This class will be facade for separating different layers of application (not to make requests from activities directly).
But now I am a little bit puzzled deciding whenever I need Content Provider or not. I can use SQLiteOpenHelper classes to retrieve and save data to the database or even use ORM library to do this.
At first I wanted to implement REST API Pattern B by Virgil Dobjanschi. But now I am not sure about this, maybe it would be better to create facade for Robospice(in my case, network request in the service) requests and do persistence there ?
Please share you thoughts about this topic, I would be grateful for any help.
EDIT
I asked this question because I feel that it is not good practice to make requests directly from activities even if they are made in service under the hood, I want to separate different layers of my application in order to make it more flexible and maintainable.
As you don't intend to share your data, i would say that implementing a ContentProvider is overkill.
Personally im a huge fan of ORM libraries (Currently i use SugarOrm in several projects), so i would go down that road.
Then at app startup, you check whether or not you have an active internet connection, and based on that you either get the latest information online, or retrieve older information from the database.
To seperate the logic a bit, i would most likely implement the getting of online information in a service, which would then store it in the database and broadcast to the activity that the information is now available, and then the activity could retrieve the information from the newly updated database.
Content Providers are absolutely for sharing data between applications and are of no use without this purpose.
If you want to use those data only in your app privately, you could use SQLite databases. Also there other objects available:
Shared Preferences
Files
Content provider has the similar interface as HTTP request (GET,POST,PUT,DELETE)
I don't think so. It's more like to SQL language.
What's the purpose of Content Provider? The document here said:
Content providers store and retrieve data and make it accessible to all applications.
I just want to store my data into Sqlite, no need to share with other application, shall I still need to use Content Provider API?
Sqlite is an Android wrapper for using SQLite DB's. It provides neat and cleaner interface for all DB operations. Ofcourse one of the major pros for using Content providers is it provides mechanism for sharing your data with other apps.
But surely even for storing and retrieving data in db, Content provider provides a nice interface and it is highly recommended.
There are other classes like SqliteDBHelper using which you can perform direct operations on DB.
i have done SQLite database programming for Android, but i dont know anything about
Content-Provider except this: "As i have referred Android Developer page , Android SDK explained about "Content-provider" as it is used to store and retrieve data."
But then,
What is the exact difference between "Content-Provider" and "SQLite Database"?
Which is best to store data, when ?
Any example or helps !!
I found one major difference, as follows:
Storing your data in a database is one good way to persist your data, but there's a caveat in Android-databases created in Android are visible only to the application that created them. That is to say, a SQLite database created on Android by one application is usable only by that application, not by other applications.
So, if you need to share data between applications, you need to use the content provider model as recommended in Android. This article presents the basics of content providers and how you can implement one.
I found this article at this link
Really nice information provided.
What is the exact difference between
"Content-Provider" and "SQLite
Database"?
ContentProvider is a facade -- an API you can implement that exposes databases to other processes. It can be implemented in a way where the data is stored in a SQLite database, but it does not have to be.
Which is best to store data, when ?
That is impossible to answer in the abstract. Generally speaking, unless something is requiring you to use a ContentProvider, just use a database.
I have made many good apps with thousands of users using them which simply used SQLite methods. But that was a while ago and I had to manually write lots of code which now can easily be taken care of by ContentProvider. Back then I was not in favour of using Content Providers because it seemed to only add complexity in the code.
However for last couple of years, as Android has evolved, I have moved to ContentProvider as it saves time and allows you do to more. I now use it extensively. Once you have a Content Provider class written, your life becomes much easier. With ContentProvider I can much easily deal with Cursor Loaders, Loader Callbacks and Bulk Inserts for which I had to write everything manually in the past and still it didn't work as efficiently. Especially when updating the list view, which is now automatically updated thanks to just one notifychange() method. This means now I don't have to type my own listeners and manually updating the content in list views and adapters. Plus, I don't need to worry about opening and closing of databases or worry about memory leaks. That's all handled by the Content Provider. The only problem which once in a while I face is that that you cannot do some complex queries in ContentProviders. In this case you can still use raw queries and use the old fashioned manual interaction with sqlite.
If you have previously written your own DbAdapter, Helper and Observer, you can safely carry them on to your new apps without spending time to convert everything to ContentProvider. But based on my experience, I would highly recommend to move to ContentProvider. It'll take some time to get used to it, but once you have got experience with it, you'll stay with it.
UPDATE 2017
I have now switched to Realm, a much better way to use databases on any platform. Spend a few hours learning it, and save countless hours in your app development career.
1. Content Providers are not Thread Safe
By default content providers are not thread safe. If you have multiple threads using a content provider you can see many different exceptions being thrown and other data inconsistencies. The easiest way to fix this is to use the synchronized keyword on each of the public methods exposed by the content provider.
In this way only one thread at a time can access these methods.
2. Play nice when doing lots of writes
I have the need in the new Serval Maps application to import data from binary files into the database used internally by the application. In order to do this and play nice with the rest of the application it is best to:
Spawn a new thread to undertake the import so other threads are not adversely impacted, in particularly the thread in charge of updating the UI; and
Pause briefly at the end of the each import to give other threads which need to use the synchronized methods more of a chance.
3. Content providers force you to think laterally sometimes
The way that content providers in Android work is to provide a layer of abstraction between the rest of your code and the underlying database. This is mainly due to the fact, as far as I can tell, that content providers can access data from places other than databases.
This means that you can’t execute raw SQL queries on the underlying database and you need to specify the various components of a SQL query using variables passed to the various methods such as the query method. If you have a task that doesn’t fit into the way that SQL is handled by a content provider you have two options:
Think laterally about the query, maybe you can get the data that you need by alternative queries and accessing the results from the cursor; and
Use a URI for accessing the data normally and a special URI that is matched to a specific query for those tasks that don’t have alternatives.
Content Providers are used when you want to share your data across applications.
If you have a database attached with an application and you want another application to use some data, you can implement a content provider that exposes the data
The main difference is: when your app needs to share information to another apps, use Content-Provider. SQLite only storage data for the app who creates it
I read this answer while looking for same doubt, so thought of sharing it.
it states -
It's good practice to provide the extra level of abstraction over your data to make it easier to change internally. What if you decide to change the underlying database structure at a later time? If you use a ContentProvider you can contain all the structural changes within it, where as if you don't use one, you are forced to change all areas of the code that are affected by the structural changes. Besides, it's nice to be able to re-use the same standard API for accessing data rather than littering your code with low-level access to the database.
So, using a content provider would be a good idea.
Think of advanced Content Management Systems. Each object (page, image, news article, event item, etc.) has a content, an address, user permissions, and ways to interact with it from different parts of the system. Content Providers do that for Android. You can now share files or images you may have stored in your application. You can also create custom sharable objects, like bussiness contacts, editable notes, etc. And specify security and the default application to deal with such object when you open them from any other application.
One difference is that Content Providers have platform support for Content Observers. Your going to need to implement your own Observable pattern for a SQLite database.
How to automatically re-query with LoaderManager
ContentObserver for SQLite?