Develop Reference

Approaches to storing data in Android

I have started learning Android development and I have a very newbie question. I understand that Android can store data in SQLite for example, but what other approaches are there to the storage of data within your application?
Do Android apps ever have data 'embedded' within the application, in which case what sort of data structure or concept would this use?
I am thinking of a scenario where the data is static but is perhaps not a large enough dataset to warrant a database..e.g. an app with general knowledge questions and answers
Any guidance much appreciated
Rowan

Yes You are correct You can use SqLite Database for storage
other ways to store data is SharedPreferences
But in your case you wanrted to save questions and answers which is static one so you can create a text file and put that in your assets folder and you can read that file as any other text file in java
Refer this link how to read file from assets folder
1.Sqlite Database
2.Shared preferences
3.Internal memory
4.external memory i.e sd card

i would suggest you to go with Database. as it will let you store as much data as your app needed, There are some other option also present like
Sharedpreference i.e. cookies in general term. It let u store only few KB data and not good to store much data. When u retrieve data from cookies. All data will be store into ram and use app memory. that is use less when u do not need all data to retrieve and store into ram and then remove
Store into file and ship that file with your app. Yeah. this could be better idea again. you need to read it byte by byte. and hence reading to mid or last line will store all data into ram and hence will take memory.
Use Web Service to download data. It will let you store Large data and you have to download using Web APi. Hence it could be better idea. But this requires active Internet connection to play game to run app.
There must be some other option also present. You can search. surely you will find them :)
Overall Database it good solution for all app. As it will let you do search store delete and let you do other operation in less amount of memory. In Mobile Development Memory is very Important thing we have to take care of.
Let me know if you have other unclear thought.
item

You could also store info in a server.
Pros :
You can change the content without needing user-side update of the app.
Cons :
Your app (mostly the UI) would need to manage connection problems.
You may need to implement async tasks for querying data from server.

Android App to talk to a web server, download a file and parse

I am new to this. I have the Android SDK installed with Eclipse. I can work with basic activities and layouts.
I am looking to write this Android application that will;
1) Allow users to sign-in using a pre-allocated password.
2) Login and change the password.
3) Every time the user opens the app, he downloads a CSV file from a server to the SD card.
4) The app parses from the file and displays them on several activities and small frames inside the app.
Think of it as an informational application. But, I'd like to add some intelligence on top of it after I get this done.
I have read many articles and topics but none of them give me a specific approach to do this faster. I have very little time for development.
If there's a similar application that you're familiar with, I'd like to take a look at the code.
I want to know exactly (the code) on how the communication between the app and a linux based server on the web needs to be established. Right now, there's only a CSV file (or an EXCEL file - which one's better to parse? How to decide?) there.
Also, when the CSV file is up to date, I wouldn't want it to download the file again. How to prevent it?
As I said, I am new - so please be patient.
Thanks

If you are new to this and want to develop something fast, why do it the hardest way, in java? There are so many easy toolkits out there, e.g. RFO.Basic, you will be amazed how much you can achieve, fast, that way.

(You asked several questions) Easiest to parse? If you don't have Excel installed on your Android device, the CSV is of course easier to parse, needing only text tools. However, if you have a choice of formats, why not use XML? If you have never worked with XML, there is a little learning curve, but there are lots of tutorials on the web. After that, you'll never want to go back to CSV.

Your last question: how to prevent download of unchanged file? Is this about a big file? In that case start with quickly downloading the hash (checksum) of the file, so that the client can decide if the file has changed.

Android, storing big number of small images linked to database

I have been asked to create a tiny android app.
In everyday work i code for .NET and I have no experience connected with Android, but as it is a really small app I guess it's going to be a good experience rather than something hard.
The core of the app would be a small database (probably XML, unless somebody suggest better solution) that would contain categories, names of the institutions assigned with each category and logo (not very high resolution I guess a single file would be <100kB) of the institution.
The database also would not be very big - I expect not more than 1000 records in total. The DB has to be totally offline and local, it cannot require Internet access when operating.
The model I assume would be to ship new version of the application when the database changes (which is not going to be very frequent).
What is the best way to deal with these requirements?
My first idea was to create an XML file that would contain the records and link to the image. The XML and all the images linked to it would be stored in single file (preferably zip) that would be stored in app resources. This is very good as it is going to be very easy to update the database.
The second idea that somebody suggested me would be to use SQLite and store images in BLOB. In general I have read that it isn't a good idea to store images in database directly, and I am afraid if it's going to be possible to meet all requirements mentioned above.
Mostly I have no idea how to update the database easily and attach it to new version of application.
Any suggestions?
I would be grateful for any response.

I wouldn't go about using XML to save your data and by no means zip anything.
I think your way of thinking is ok, but you're making things really complicated for yourself.
Seeing as you're used to .NET I suppose you're also pretty confident with SQL, so I'd suggest you have a look at how to use the built-in SQLite database in Android.
If you would go the XML route you'd have to serialize and de-serialize the XML file over and over again and then parse the XML. Ok you don't have a lot of data, but searching inside an XML file with at least 1000 nodes would be slow in comparison to the performance of a database.
Also upgrading an existing SQLite database is not that hard - Android has methods for that (onUpgrade coming from the SQLiteOpenHelper).
As to saving images I'm assuming that you won't fetch new pictures from the Internet, so it would be best just to store them in the drawable folder of your app (be mindful of different screensizes) and then reading them into an ImageView when needed. To figure out what image should go for what institution I would store either the image name of each image in the SQLite database or store the resource id for each image in the database - for instance R.drawable.myawesomepictureformyinstitution.
I know my answer is somewhat "superficial", but your question is also somewhat "broad" and hard to answer without me actually writing most of the code, and that's not my intention ;-)
Hope this helps - let me know if anything is unclear.

Android Storing RSS feed parsed data in a database for offline use

I am parsing a Rss feed using sax parser in android. I am able to display the data online when net is connected but i also want it to work for offline use and update it when it gets connected again to internet / wifi. I have no clue how to go about it.
What should be my best approach now ? should i construct Sql database ? considering i have images as well.
Or there is any other simpler way. I would prefer simpler way.
I need some further suggestion on the Sql database approach here, First : My rss feeds gives image url links which i diplay using bitmap and insutstream at runtime but now for offline purpose i need to save complete images like whatsapp does right ? is this right ? if yes how to save complete images in database ? And last i want to save the complete database on sd card not in internal memory , storing data on sd card will work fine or it will create problem ? because whatsapp stores quite a data in internal memory !! if storing on sd card is not a problem how do i store complete data on sd card ?

This depends on how long you want the data to persist. Ask yourself:
Should this data be available to the users after rebooting the phone, or after force closing the app? Should it be available regardless of the last time I had connectivity, as up to date as possible given that?
In that case, then yes - you should use a database. Android has a number of built in helper classes for sqlite databases.
http://developer.android.com/training/basics/data-storage/databases.html
Which should get you started.
The images are pretty straight forward as you'll just stash a reference to the image(s) in the db. You would of course write these images to disk as well (on the sd card or some other place...) See:
Save bitmap to location
Your other options, afaik are:
1) SharedPreferences (not really suited to this).
2) Serializing your data and writing out/reading in from some file.
If you're still looking for more information on Database concepts and Android, here is a very good tutorial on the topic:
http://www.vogella.com/articles/AndroidSQLite/article.html

You can use droidQuery to download the RSS Feed and cache it. Working off of this gist, which expects you to use the android-rss library, you can add the following cache flags to your AjaxOptions object:
.cache(true).cacheTimeout(AjaxCache.TIMEOUT_NEVER)
This will make it so the response is cached until you explicitly call:
AjaxCache.sharedCache().clearCache();
Which you can do after the network is connected (for help on this, check out NetWatcher).
Note that using this cacheing mechanism allows a very simple solution that will only store as long as the app process is live. If you want to save across sessions - so that if the user opens the app later and is not online, you will want to use something more complex and long-lasting, such as SharedPreferences or SQLite. A good list of options can be found here.

How to handle data in android

Im working on a self-test app.
And I wondering on how to store the data, I've got over 200 questions and more is on the way.
Was thinking of storing them as XML but didnt find a way to get a random question without reading the whole string-array to a variable, which is bad for the memory.
So the correct way to go is to use a SQL-database, right?
But how do I make such a database so that it exists at boot and dont need to be made during start up?
Can't seem to find any tutorial on this subject, on how to handle questionnaires.

Here's a good tutorial on SQLite and Content Provider. It'll introduce you to using SQL databases on Android, and wrapping them into a ContentProvider.
As for how to get the data to the device - you have two options:
You pack the SQLite .db file in the application assets folder. Pros: the database is ready for consumption on the first run of the app. Cons: your .apk is too big. Updating is hard.
You download the data on the first run. Pros: your .apk is slim. updating is easy Cons: there's a delay before the user can use the app.
You ship a small .db file with the first 10 questions. Pros: Your users can start using the app immediately, while you download the rest of the questions in the background. Cons: You have to pick 10 questions you're likely to never or rarely change, or you risk your app to start with outdated data.

Create the db offline and either put it in the apk or download it.