SharedPreferencesHelpers - PerfectCarl/androidannotations GitHub Wiki

Since AndroidAnnotations 2.1

SharedPreferences helpers allow you to use Android SharedPreferences, but in a typesafe manner, instead of using strings.

Defining the preferences

First, you should create an interface annotated with @SharedPref to define the SharedPreferences :

@SharedPref
public interface MyPrefs {

        // The field name will have default value "John"
	@DefaultString("John")
	String name();

        // The field age will have default value 42
	@DefaultInt(42)
	int age();

        // The field lastUpdated will have default value 0
	long lastUpdated();

}

Based on that specification, AndroidAnnotations builds a SharedPreferences Helper that has the same name plus an underscore. You can get an instance of the generated helper in any enhanced class with the @Pref annotation.

Important: The type of the field MUST be the generated class instead of the source class. It's the only exception in AA.

@EActivity
public class MyActivity extends Activity {

	@Pref
	MyPrefs_ myPrefs;
	
	// ...

}

You can then start using it:

// Simple edit
myPrefs.name().put("John");

// Batch edit
myPrefs.edit()
  .name()
  .put("John")
  .age()
  .put(42)
  .apply();

// Preference clearing:
myPrefs.clear();

// Check if a value exists:
boolean nameExists = myPrefs.name().exists();

// Reading a value
long lastUpdated = myPrefs.lastUpdated().get();

// Reading a value and providing a fallback default value
long now = System.currentTimeMillis();
long lastUpdated = myPrefs.lastUpdated().getOr(now);

Default resource value

Since AndroidAnnotations 3.0

It's now possible to inject a default value from Android resources with @DefaultRes:

@SharedPref
public interface MyPrefs {
    @DefaultRes(R.string.defaultPrefName)
    String resourceName();

    @DefaultRes
    String defaultPrefAge();
}

Scope

Observe that you can name the shared preference by setting value to one of the following:

• ACTIVITY, for a shared preference named MyActivity_MyPrefs;
• ACTIVITY_DEFAULT, for a shared preference named MyActivity (also available through activity.getPreferences());
• APPLICATION_DEFAULT, for the default SharedPreference or UNIQUE, for a shared preference named MyPrefs.

Therefore, if a single shared preference is needed for the interface defined, in order to all activities of a given application to share the same preferences, the following should be used:

@SharedPref(value=SharedPref.Scope.UNIQUE)
public interface MyPrefs {
...

Using it with a PreferenceActivity

The Android PreferenceActivity can edit the values of your shared preferences.

@SharedPref()
public interface MyPrefs {
...
}

public class PrefsActivity extends PreferenceActivity {

	public static String PREF_NAME = "MyPrefs";

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);

                // Using your MyPrefs values 
		this.getPreferenceManager().setSharedPreferencesName(PREF_NAME);

                // Opening the layout 
		addPreferencesFromResource(R.xml.prefs);
	}
}