CODEWITHSUNDEEP
androidsharedpreferences
kowal256
kowal256

Reputation: 53

Is there way to use PreferenceActivity without storing values in shared preferences

I have an android application that has uses few serializable classes (I can store and load them in JSON format using Google Gson library and it works like a charm).

Now I want to provide way for user to edit those objects in fashion similar to PreferenceActivity - they contain few strings, ints and doubles and PreferenceScreen just seems ideal for editing them.

Is there a way to 'abuse' PreferenceActivity to provide UI for editing my objects without actually storing data in shared preferences?

For example - if there was some callback to override that is called just before saving data, I could extract data, assemble my object and somehow prevent Android from messing with preferences?

Upvotes: 2

Views: 494

Answers (2)

Kevin Krumwiede
Kevin Krumwiede

Reputation: 10308

SharedPreferences is an interface, so you should be able to provide your own implementation that stores data however you like. But the PreferenceManager used by PreferenceFragment only has a setter that takes a file name, not a custom implementation of SharedPreferences.

I looked into the source and found a roundabout way to use your own implementation. PreferenceFragment uses its hosting Activity as the Context for constructing a PreferenceManager. PreferenceManager subsequently calls Context#getSharedPreferences(String, int) to get the SharedPreferences that it will use. Therefore, you can override getSharedPreferences in the activity hosting your PreferenceFragment and return your custom implementation. Implementing SharedPreferences could be rather complicated since you'll also have to implement SharedPreferences.Editor, but it's doable. And if there's any chance of your overridden getSharedPreferences being used anywhere else, you should document that it uses a different backing store.

In the Android O preview, there's a new interface called PreferenceDataStore and a new setter in PreferenceManager that takes an instance of that interface. PreferenceDataStore looks much simpler to implement than SharedPreferences. But as I write this, most retailers are still selling L and M devices, so who knows when we'll see O.

Upvotes: 2

Eugen Martynov
Eugen Martynov

Reputation: 20140

First I would think if I really want to present objects editing with preferences UI since it might confuse a user.

If you still decide to go this way you can achieve it with:

  1. Serialise every object in separate shared preference file and use preference activity how it is designed
  2. Write own PreferenceManager and use reflection to replace private field in PreferenceActivity

The first one is straight forward and rather simple to implement, might have some performance implications. The second one might get tricky and probably requires more code to write.

I would still advice to revise decision to "re-use" PreferenceActivity for such case.

Upvotes: 1

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