Android Object Handling / Persistence

I am pretty far into my first Android application, and I have the sneaking suspicion that I'm 'Doing It Wrong'. My app talks to a Ruby on Rails server and serializes objects back

Solution 1:

I wouldn't approach your Android application as an extension of a Ruby app - rather a consumer of an API. If you can try to expose your server application as JSON (or other format, but JSON is the most lightweight) and consume these APIs from your Android application you would most likely have less problems as JSON is already in K/V format.

I have not yet written Android objects to SQLite yet, but I have written them as both Parcelable objects and to the SharedPreferences. Both of these strategies are sufficient for small to mid-range apps. For data intensive apps, obviously you will have to take it a step further to SQLite.

There are some great articles for these approaches: Managing State.

It boils down to designing your objects in a way that can be serialized easily. That means no circular references or extremely complex objects. This shouldn't be a very large problem, especially if your data is in JSON format already. You simply need to extend some classes and add functions that return a Parcelable object representation or a string representation so your objects can be saved thus.

I would avoid cloning your server-side objects and validation in Android as it then requires modifying both sources if you make small changes. The server should handle all data and validation and you should simply be requesting, caching, and sending data from Android.

I'd be interested to hear if there any challenges to writing objects to SQLite, but I imagine it's not that much more of step from the details I've outlined above. Hope this helps in some capacity!

Solution 2:

Hessian is great for RPC. You don't have to do any serialization yourself. It doesn't use XML, so it's more efficient and more appropriate for a mobile platform.

Solution 3:

I haven't done much of persistence storage on Android but I think you need to use SQLiteDatabase and make your own Cusor that De/Serializes your object so that it can be added to the database. A possible solution would be to extend a SQLiteCursor or an AbstractCursor.

Otherwise I don't think there is other solution apart from, possibly, "hardcore" Serializabled (Which I suspect it may be too much for a phone, I may be wrong)

Solution 4:

I think you might be going too heavy for a smart phone application. I would look at using RESTful style web services with JSON content.

Solution 5:

Looking to your question I got the feeling that maybe you just over-complicating your requirements? Why can't you just use JSON format to represent your objects data in portable way? Then you will be able just to store it either on file system or in database in simple text field. You can leverage android-active-record library for transparent DB persistence (http://code.google.com/p/android-active-record)