Android - How Do I Set A Preference In Code

Question

I have an Android application in which I have my preferences in an XML file, which works fine. I now want to set one of the preferences using code instead of displaying the entire preference screen, how would I go about doing this?

Answer 1

I assume by preferences you are referring to your application's preferences and not Android phone settings.

To store preferences between runs of you application you need to do the following

1. Create a SharedPreferences object

   SharedPreferences settings = getSharedPreferences(String n, MODE_PRIVATE);
   

   String n identifies your preferences and the second argument is the mode they'll be accessed

2. Instantiate an Editor object

   SharedPreferences.Editor editor = settings.edit();
   

   Note: do not try settings.editor.edit(), this will not make a persistent object and the code below will not work

3. Write your preferences to the buffer

   editor.put...(String, value)
   

   There are numerous put function, putString, putBoolean, etc. The String is the key ("version", "good run") and the value is the value ("1.5.2", true)

4. Flush the buffer

   editor.commit();
   

   This actually writes you put to the preferences. If your app crashes before this line then the preferences will not be written. There is also a documented bug: commit() is supposed to return a boolean indicating success or failure. Last I checked it always returned false.

These preferences will by stored on the phone and will only be accessible to your application.

More documentation is here

Answer 2

I tried this but didn't work:

SharedPreferences settings = getSharedPreferences(String n, MODE_PRIVATE);

Try this instead:

SharedPreferences settings = PreferenceManager.getDefaultSharedPreferences(this);

Answer 3

You can save something in the sharedpreferences by using below code

public static void save(String valueKey, String value) {
    SharedPreferences prefs = PreferenceManager
            .getDefaultSharedPreferences(context);
    SharedPreferences.Editor edit = prefs.edit();
    edit.putString(valueKey, value);
    edit.commit();
    }

To read preferences:

public static String read(String valueKey, String valueDefault) {
    SharedPreferences prefs = PreferenceManager
            .getDefaultSharedPreferences(context);
   return prefs.getString(valueKey, valueDefault);
}