OnPreferenceChangeListener in Different Process - Sharing Preference Data
public class ServiceA/B extends serice implements OnSharedPreferenceChangeListener{
    @Overside
    public void onCreate(....){
        Settings.getPrefs(this).registerOnSharedPreferenceChangeListener(this);

     }
    @Override
    protected void onResume() {
        super.onResume();
        Settings.getPrefs(this).registerOnSharedPreferenceChangeListener(this);
    }

    @Override
    protected void onPause() {
        super.onPause();
        // Unregister the listener whenever a key changes
        Settings.getPrefs(this)
                .unregisterOnSharedPreferenceChangeListener(this);
    }
    public void onSharedPreferenceChanged(SharedPreferences sharedPreferences,
        String key) {
    System.out.println("++"+key+"++");
    if(key == "KEYA"||key == "KEYC")
        Do_what_ever_you_want();
            if (key == "KEYB")
        do_anything();
    }
    do_anything(){}
    Do_what_ever_you_want();
}

public class Settings extends PreferenceActivity implements
OnSharedPreferenceChangeListener{
      public static final String PREFS_PRIVATE = "PREFS_PRIVATE";
      public static final String MASTERKEY = "!@#$%^&*";

      public static final String KEYA = "KEYA";
      public static final String KEYB = "KEYB";
      public static final String KEYC = "KEYC";

       --- the create and get methods for getting and sharing data in the prefs... .....
      // get them from just a google search.

}