Figure 15-1: The preferences screen for the call settings in Android.
Understanding the PreferenceActivity Class
The responsibility of the PreferenceActivity
class is to show a hierarchy of Preference
objects as lists, possibly spanning multiple screens, as shown in Figure 15-1.
When preferences are edited, they’re stored using an instance of Shared Preferences
. The SharedPreferences
class is an interface for accessing and modifying preference data returned by getSharedPreferences()
from any Context
object.
A PreferenceActivity
is a base class that’s similar to the Activity
base class. However, the PreferenceActivity
behaves a bit differently. One of the most important features that the PreferenceActivity
handles is the displaying of preferences in the visual style that resembles the system preferences. This gives your application a consistent feel across the board in regard to Android user interface components. You should use the PreferenceActivity
when dealing with preferences screens in your Android applications.
Persisting preference values
Because the Android framework stores preferences in the Shared Preferences
, which automatically stores the preference data in internal storage, you can easily create a preference. When a user edits a preference, the value is automatically saved for you; you don’t have to do any persisting yourself.
Figure 15-2 shows a preference being ...
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