从服务中读取时首选项不是最新的

Question

I have the a very simple preferences implementation in my app. This is my Preferences activity:

public class Preferences extends PreferenceActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState); 
        addPreferencesFromResource(R.xml.preferences);
    }
}

Every activity or service that reads preferences does this:

preferences = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());

Now, one of the settings is a server the app connects to. This is implemented as an unbound service because it's supposed to remain online even when the user left the app. When the service starts (onStartCommand), the socket information is read from the preferences.

The problem: After changing a preference and restarting the service it still has the old value.

I don't get it! Please help :)

---

Here's a little more detail since its still not working. My guess my error lies somewhere else ...

My service looks as follows.

public class XMPPService2 extends Service {
    SharedPreferences preferences;

public void onCreate() { ... }

public int onStartCommand(Intent intent, int flags, int startId) {
    preferences = getSharedPreferences("com.company.appname_preferences.xml", MODE_MULTI_PROCESS);
    Log.d(TAG, preferences.getString("server", "DEFAULT")); // this always prints the default value
}

public void onDestroy() { ... }

}

As far as I understand, there is not much more I have to do about it. I've also tried to

getPreferenceManager().setSharedPreferencesMode(MODE_MULTI_PROCESS);

before

addPreferencesFromResource(R.xml.preferences);

but this didn't help.

Now, I know that these methods are deprecated. However, I have to make sure the app runs on tablets as well as 2.3 devices.

I just wanted to mention that I'm still new to android and maybe I've misunderstood some basic concept. The answers I've gotten coincide with my web research, so i expect them to be correct.

Answer 1

If you are trying to access a shared preference from a different process (even though they are in same package), you need to use MODE_MULTIPROCESS.

Please use the following code:

 SharedPreferences pref = getSharedPreferences("com.mypackage.myapp_preferences", MODE_MULTI_PROCESS);

The important thing is to use MODE_MULTI_PROCESS and name of your preference file.

Answer 2

To share the preferences between processes, you need to have *MODE_MULTI_PROCESS* set on the preferences file. Problem is that you can't control flags of the default preferences file, right? Well, There's a way. In your PreferenceActivity class, add these lines to onCreate() :

PreferenceManager prefMgr = getPreferenceManager();
prefMgr.setSharedPreferencesName("preferences");
prefMgr.setSharedPreferencesMode(MODE_MULTI_PROCESS);

Then instead of using PreferenceManager.getDefaultSharedPreferences , get the preferences from the file using:

getSharedPreferences("preferences", MODE_MULTI_PROCESS);

Answer 3

It could be because the method addPreferencesFromResource() is depreciated in API 11:

Read more here

More likely there is a problem with how the preference is being committed. Could you post your XML?

Answer 4

You have to read your preferences from the same package. Move your service to the same package as the preference activity and you are done.

Answer 5

这似乎是 android 中的一个错误： https : //code.google.com/p/android/issues/detail? id =66625