android-context

I am using several SharedPreferences to store data in my app. Some preferences are used in a lot of activites. I know that the SharedPreferences are internally backed by a map for fast read-access and written to sdcard when settings are changed. I wonder which way is better if a sharedpreference is accessed by a lot of activies: Instantiate it in every activity using the activity context. Instantiate it in every activity, but using the application context. Put it in e.g. the Application class and instantiate it only once there, similar to a singleton. If I use 1. solution is there a

I've read that it is a mistake and a source of memory leaks in Android application to keep a long-lived references to a Context. But I don't understand if it is ok to create a class that looks like this one: public class HelperClass { private Context context; public HelperClass(Context context) { this.context = context; } public void myHelperMethod() { // uses this.context } } And call it from an Activity: public class MyActivity extends Activity { public void onCreate(Bundle savedInstanceState) { HelperClass h = new HelperClass(this); h.myHelperMethod(); } ... } This is fine, and will not

Can somebody explain this to me please : Intent intent = new Intent(Context, AlarmReceiver.class); I never understood and I seriously think I never will if somebody doesn't try to explain this to me in depth. This whole context thing is so confusing to me. Sometimes it works like this : Intent intent = new Intent(getBaseContext(), AlarmReceiver.class); Sometimes it wont work like that but it accepts only : Intent intent = new Intent(context, AlarmReceiver.class); Sometimes its : Intent intent = new Intent(this, AlarmReceiver.class); etc. etc. and many other. I understand basics of context but

I'm using this code below to change my app language on button click (changing from french to english for example), it's works fine on android 4.0 + but on 5.0 it doesn't. Locale localeEn = new Locale("en_US"); Locale.setDefault(localeEn); Configuration configEn = new Configuration(); configEn.locale = localeEn; getApplicationContext().getResources().updateConfiguration(configEn, null); this.recreate(); Any clues why please? edit : this is my manifest ( with android:configChanges ) <activity android:name=".activities.LoginActivity" android:configChanges="orientation|locale" android:label="

I have got a question regarding the usage of context in a fragment. My problem is that I always get a NullpointerException. Here is what i do: Create a class that extends the SherlockFragment. In that class I have an instance of another Helper class: public class Fragment extends SherlockFragment { private Helper helper = new Helper(this.getActivity()); // More code ... } Here is an extract of the other Helper class: public class Helper { public Helper(Context context) { this.context = context; } // More code ... } Everytime I call context.someMethod (e.g. context.getResources() ) I get a