Android: la mejor manera de guardar datos almacenados en la aplicación Singleton Class

Question

¿Cuál es la mejor manera de guardar los datos almacenados en la clase de aplicación (Singleton) de una aplicación de Android?

Tengo una gran aplicación tranquila que comparte muchos datos entre las actividades. Así que la mayor parte está almacenada en la aplicación Singleton.

Todo funciona .. utilizado. La aplicación es asesinada por el sistema operativo en la memoria baja ... luego, cuando vuelve, intenta reanudar la actividad sin éxito debido a la falta de datos necesarios. < / p>

Debido a la falta de un método muy apreciado (y necesario) para guardar datos sobre la aplicación de acuerdo con su experiencia, ¿cuáles son los mejores enfoques?

¿Puedo guardar cosas, además de las cuerdas "normales", booleans, etc., como mapas de bits?

Ya he visto esto ¿Cómo declarar las variables globales en Android? Pero la pregunta no se está enfocando en lo que es importante en este caso, cómo guardar los datos cuando la aplicación se mata debido a la memoria baja ...

Answer 1

As with many questions, there is no simple answer. There are many ways to save data and each has advantages and disadvantages. The "best" approach will depend on your particular needs. You have all your options here: http://developer.android.com/guide/topics/data/data-storage.html

• For a few, small bitmaps, you might encode them and store them in the SharedPreferences.
• For more and bigger images, you have two options
  1. A blob column in a database
  2. Store them as files in your internal storage, and keep the links in your preferences.

SharedPreferences stores strings, so anything that is a string can be stored, including any serialized/encoded object. According to this post, there is no hardcoded size limit for a serialized string in SharedPreferences, but is based on the String size limit. Nevertheless, this other post points out that the whole SharedPreferences object is written as a single xml file, so you should try to keep its size to a minimum.

JSON object (or using GSON as suggested by katit) are a good lightweight option, but the approach I would take is to save them to the internal data storage (unless the data is really big, i.e., many megabytes, and you prefer the external storage) and keep the links only in the SharedPreferences. I don't know what your objects look like, but if they can be reduced to a bunch of simpler components, you can consider a database for them (i.e., one row per object, one column per field, including perhaps a few blobs).

The files vs database approach would depend also on how many times are you planning to access those objects. If they will be read one or two times only and then disappear, then I would choose files over the hassle of the database and its cursors. I would choose a db if there will be many reads, and perhaps you need a faster search using queries.

Check also this post: http://android-developers.blogspot.in/2009/02/faster-screen-orientation-change.html for an Activity-specific option.

Answer 2

It's important to note that if you are using a singleton class to hold your information and your application is forced to stop, the information will be cleared.

For shared preferences the information will remain the same.

Hope this helps.

Answer 3

There is Java serializer, not sure is that what you need.

I personally use GSON for all of that. It's google library to work with JSON. It allows to serialize objects into efficient string representation.

I used this mainly for RESTful service communication but then learned that it works very good to store object representation to SQLLite or whatever. I can inflate object very easy this way.