I am looking to use an XML file to store the data my Android app generates. With that in mind, I have two questions for the community:
Is XML the best way to store data on Android and most efficient in cases where data may be added or altered every second or less then a second.
If XML is indeed the best for the scenario described in #1, how do I go about setting it up?
1.) Is XML the best way to database data on android and most efficient in cases where data may be added or altered every second or less then a second.
Definitely not.
2.) If XML is indeed the best for the scenario described in #1, how do I go about setting it up?
If you plan to store data just locally, the best way would be SQLite which works as a local database on every device.
If you later plan to synchronize this data with a central database, you may do this asynchronously within an AsyncTask or a Thread which would run periodically, but writing each second into a XML file is a bad idea as far as performance goes.
It's probably also a bad idea synchronizing a remote database at each insert/modification/deletion operation as if you had many users you could collapse the remote database.
I think the best approach is (as previously said) having a local database where you would store that data, and implement a webservice in the remote side if needed and use it to periodically synchronize both databases.
I would use JSON over XML and I would highly consider using GSON from Google. You maybe want to consider writing directly to a database with it's own structure and use transactions and sets. Is there are reason you want to go through JSON/XML?
XML is one of the worst ideas to keep local data in Android.
Most common used is SQLite available on the Android platform, but it all depends on what data and how you want to use.
In many mobile applications you don't need the relational database for one of the following reasons:
You have no relational data (i.e. settings) => no point in making relational tables with 1 record each
You have small, and dynamically changed data (like cache for downloaded content)
You don't need to search for data (using indexes etc.)
What alternatives can be used?
Shared preferences - simple key/value storage of primitive objects
Data serialization - for your consideration - binary (native java), JSON, parcelable (can be combined with the shared preferences)
For most of my app I'm currently using the binary serialization for "local storage".
- It's fast enough (usually much faster than starting the local SQLite engine)
- It's extremely easy and quick to implement, especially when you are using it for json/xml downloaded data parsed to POJO objects. All you need to do is just put "extends serializable" and put few lines of code to serialize/deserialize whole structure
- You can use those same classes for keeping data locally and communication with backend
Of course - it all depends from the situation - if you want to keep locally log of data from some sensor, or allow others apps to use this data, have to quick filter 1k+ records, or you really like to write few hundreds lines of code SQLite will be the best option for you. But most of mobile applications has no clear reason to use the relational (and trust me - not perfect one) engine.
Related
I have been looking at different ways to hold onto some predefined character data, however I am having a hard time nailing down which would be the best solution.
An example of data would be 10 strings, 5 int arrays (of size 10 each). There would be 10+ set's of this data. The application would load in the information and inflate generic "character" objects.
Possible solutions:
XML: Due to Android's structured XML requirements it can be hard to use without making a different XML file for every character, and even then it would have ID overlapping for similar named data values.
SQLite: Wouldn't be a huge database, but databases are ugly version controlled unless it is done with a create-database script which has its own downsides (such as making sure DB is up to date between builds).
Hard-coded Objects: By far my least favorite solution, using polymorphism to hardcode all of the objects. Too dirty, not nearly as dynamic as it should be.
I would like to consider things such as version controlling the files, ease of updating (due to them only being inflated, never changed by the app).
If this data is baked i would suggest to use harcoded data.
Reasons.
In those three solution you save the data in the application.
If you use XML-data, you have to consume the time while code parsing inside the code. And you have to write the code that parses your xml.
If you use SQLite, your data will be doubled because of you have to store this database in raw or assest directory, copied in the /data/data folder. Futhermore, if you use Strings and SQLite by default the data will be doubled again (due to UTF-16 encoding).
If think, if only you manage the data this is more usefull to store directly inside the code. Obviously, if you do not use tons of content:)
You might want to use the Realm framework, which is comparatively faster than SQLite and easy to implement inside in your current code.
It handles large data too and it feels like you're using only native android classes.
I have read through the Android Storage Options and I have a question that I haven't been able to find the answer to:
Should I use SQLite to store my data or should I use a JSON object that is written to a file?
Requirements:
Store (up to) a few hundred instances of the same object. Each instance will be somewhat complex, storing reference to images, smaller objects, etc. The data will be stored locally, with the option of cloud backup. All the data will be loaded on startup and saved when manipulated by the user.
The reason I ask this is because I don't have a lot of data to store - for a SQLite database there will probably never be more than a few 100 rows, which makes me think SQL is overkill.
Also, exporting my data to a JSON file will allow me to easily import/export from different device platforms (I already do this on iOS).
Or, maybe there's a better option? If there was an NSCoding type library for Android I would probably use that.
Any opinions are helpful.
Thanks!
From the presented so far, storing in files will be more advantageous.
Considering that each "unit" is less than 16 attributes, a json file with short identifiers will likely generate a larger file representation than the SQL representation equivalent.
However, the local file manipulation will allow for easier interactions, as well as easier backing up/down.
Also, the File class is simple enough to generate less issues when compared to SQL.
Finally, given the choices, you are going to have to evaluate the operations used.
If you are going to compare the data, then SQL is likely to go faster, but if you are just inputting/outputting each data as a separate object, than files are going to be as fast as SQL.
Finally, please, particionate your objects, do not create just 1 file with all the info.
I have read through the Android Storage Options and I have a question
that I haven't been able to find the answer to:
Should I use SQLite to store my data or should I use a JSON object
that is written to a file?
You need to analyse your requirement again.
maybe there's a better option?
It depends upon your requirement.
if Your requirement is fixed to simply storing and retrieving then you can have a look on tinnyDB, which is basically using the SharedPreferences as storage mechanism. But if you need case base based selection/query of data then you should go with SQLite.
I am trying to build a application which will be a Ebook kind of (Lot of theory & diagrams) will be there.
Now what i want to know is that since there are many ways of storing the data which one will be the best
Storing in Database
XML
Or simple text files
I am very concerned about the security of the data as well. Since this will be a paid app, i want the data to be secured and also be fast and convenient.
Also, I thought of converting the doc files (Data) in to epub format & then use epub api's to access the data and show it on the android app screen, will this be a gud idea to go for? as compared to the above ways?
Which one will be more secure, fast, flexible & easy!
It depends on how you will access to this data. If you will store in xml you will must to read the whole file from the start to access to chapter (or load to memory, for example). It's not good idea if you will store big data.
Storing in SQL faster. You can gain access to any chapter. You don't need to read all data, like in xml.
Simple text file has the same problem like XML (xml is textfile).
The only one way to secure you data - encrypt it. If user will get root on their device, he will gain access to your files and databases. There is no meaning where you will store your data.
Depends on what is more important to you - speed or security.
Speed
Definitely SQLite, it isn't exactly the cleanest, but definitely the fastest way.
Security
Custom files which are encrypted - it will take a while to read the whole file and then decrypt it in order to display it, but you can be sure that the attacker will access the files encrypted and without the knowledge of the encryption - those data would be useless to him.
EPUB
If you're concerned about security then don't, unless you know how to apply DRM...and that is not a way to go honestly.
I think that the best way to store big amount of data is database. In Android it is sqlite database. I recommend you to put all your text data into sqlite database. You can structure it in easy and beautiful way. Then put your images into assets folder and store the pathes to the the images in database.
Advantages of database solution:
Always well structured data
Easy way to update data with version control system.
You can store and get fast accesses to really big amount of data.
You can use encryption to protect your data.
Disadvantages
It is more complicate to write good code for database solution then for XML or JSON one.
P.S If you will decide to use XML I recommend you to change it to JSON. It is faster and easier to use.
Which one will be more secure, fast, flexible & easy!
Secure: It mainly depends on encryption system.
Fast: SQLite, you can read some advantages of SQLite here Android Performance : Flat file vs SQLite
Flexible and easy: Storing the encrypted files in internal storage is a flexible and easy way. I think it is secure enough. Here you can get some android security tips about storing data http://developer.android.com/training/articles/security-tips.html#StoringData
for saving little data you can use xml for strings but you lose fast loading factor
sqlite is good for almost every purpose, but Security
I have an Android app that needs to work offline and requires a lot of static data.
Currently I'm using a JSON file in the /res/raw and loading it with the Jackson parser into my POJO scheme. It works really well since I have an external program that will be generating this data and once in a while when there is a change I'll just publish new version to the Market so I don't have to deal with running an update server and so on.
However, right now my JSON file is about 2.5MB with limited dataset for testing, in the end it'll be about 5-10MB.
The issue is that it already takes about 3-5 seconds to parse the file and this needs to be done every time the application is restarted.
So, what are my options here? I could put the data to a sqlite database, but that would require rewriting the external application and changing the data structure quite a bit. But then I could only query the things I need at the moment and not loading the entire thing at once.
Is there some easier/better way? Also, is there a good way to publish the app with the sqlite database? All the articles I've found talk about creating the database for user data at first startup, but this is not user data and I need it to be deployed from the Market.
JSON feels like the wrong approach for this - it's a good way to encode data to transfer, but that's pretty much it.
It'd be nice to have a bit more info on what exactly your app does, but I'm struggling to imagine a use-case where having several MB of POJOs in memory is an efficient solution. I think it'd be much better to use SQLite, and this is why:
I could put the data to a sqlite database, but that would require rewriting the external application and changing the data structure quite a bit.
You can still use your other program's JSON output, but instead of loading everything into POJOs with Jackson, you could populate the database on first app launch. This way, the app boot time is negligible if the dataset is unchanged.
If you still want to work with POJOs in the rest of your app, it'd be trivial to write a query that retrieved data from the database, and created objects in the same manner as Jackson.
But then I could only query the things I need at the moment and not loading the entire thing at once.
What're you doing that requires access to all the data at once? Searching or ordering a set of objects is always going to be slower than a SQL query to achieve the same thing.
Also, is there a good way to publish the app with the sqlite database?
You can definitely ship your app with a database, though I've not done so personally. This is a relevant question:
By Default load some data into our database sqlite
Hope that's of some help.
There's an excellent API called JExcel (just google it) that works with .xls spreadsheets. If you're not going to be doing any selecting and just loading data from a source, I like to use JExcel because it's more manageable from a desktop and produces easier-to-read code.
Not sure of any performance differences, however. Just throwing in my 2 cents :p
I am developing an application that periodically sends information to an external server. I make a local copy of the data being sent, for backup purposes.
What is the best option to store the data in terms of saving battery life? Each data submission is a serialized object (the class has 5 fields, including a date, numbers and strings) of about 5K-10K.
Any other idea?
I don't believe it matters whether you use SQLite or a File, because the SQLite db is simply a file on the system (stored in /data/data/<your_package>/databases/). You'll need to commit to the db at the right times, just as much as you would need to save a file to the hard drive at the right times. In other words, one way or the other you can use just as many hard drive writes.
I think that what you choose depends more on what sort of data you are saving. If you need the powers that having a db can bestow (such as querying), then by all means use SQLite. However, if you don't need a db, or you've got data that varies wildly (and can't be easily setup in a relational database) then I'd go with files.
What I can tell you for sure is that you should not use serialization for saving a file, if that is the route you choose to go. Android serialization is slow, slow, slow and creates large files. It is much better to either write your own XML or JSON format for performance reasons.
I have no idea in terms of battery life directly but one criteria would be which is easier to manage? Fewer operations to manage the data would mean fewer CPU cycles and in turn longer battery life.
I would say the SQLite option is easier. You can put a date column in the SQLite table which stores your data which makes removing old submissions which you don't need any more very easy - and all handled via the native SQL library. Managing a whole load of file - or worse a single file - with your own Java code would be much more work.
Additionally, you can write data the to database and just forget about it until you need to read it again. If you're storing data in files, you'll need to work out when you should be reading and writing files in terms on the Android application life cycle. If you're worried about battery you probably wouldn't want to write files more often than you should, and cache data in memory, but you'd need to make sure you didn't lose any data when your app is Paused or Destroyed. In my opinion it's much easier to use an SQLite database and not worry about any of this.
Is your application multi-threaded? If you have multiple threads accessing the data store then I would go with SQLite. Let SQLite worry about locking issues.