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PreferenceManager.setDefaultValues does not work for custom Preferences

I'm working on a little app with a lot of modifiable preferences, most of them being SeekBarPreferences.
It happens that, since I'm quite not happy with Android default SeekBarPreferences, I'm using the very good MaterialSeekBarPreference library which unfortunately have not been updated for 2 years.
Here is an example of code used by this library:
<com.pavelsikun.seekbarpreference.SeekBarPreference
android:key="#string/param_maxEvent"
android:title="Blahlblahblahblahblah"
android:summary="Blahlblahblahblahblah too"
android:defaultValue="2"
custom:msbp_minValue="0"
custom:msbp_maxValue="5"
custom:msbp_measurementUnit="events"
custom:msbp_interval="1"
custom:msbp_dialogEnabled="false"/>
As you can see, you can use the android:defaultValue xml attribute, and it works perfectly with the UI.
Since I need to load all these default values at app initialization, I use the PreferenceManager.setDefaultValues method:
public class App extends Application {
#Override public void onCreate() {
super.onCreate();
PreferenceManager.setDefaultValues(this, R.xml.preferences, true);
}
}
This works fine with all default preferences (SwitchPreference, ListPreference, Preference), but unfortunately not with these custom SeekBarPreference.
Loading the preferences activity does not set up thoses default values either.
Is there any workaround for this problem ? Else, if I was up to edit the library, what should I change ?

I don't use the method PreferenceManager.getDefaultSharedPreferences(this, R.xml.preferences, true);. Instead, I use preference.setDefaultValue(object); in the Fragment.

How can I reuse code when creating multiple preferences.xml files on Android?

I want to display different preference options in my app depending on the device SDK and screen size, but certain preferences will be displayed on all devices. I could accomplish this by creating a full preferences.xml file for each possible device, like this:
xml/preferences.xml:
<PreferenceScreen>
<!-- Preference 1 (all devices) -->
<!-- Preference 2 (all devices) -->
</PreferenceScreen>
xml-v21/preferences.xml:
<PreferenceScreen>
<!-- Preference 1 (all devices) -->
<!-- Preference 2 (all devices) -->
<!-- Preference 3 (SDK 21 only) -->
</PreferenceScreen>
But this will get unwieldy very quickly given the number of possible combinations of screen sizes and SDKs. What I'd really like to do would be to use the same basic list of preferences on all devices and dynamically mix in additional preferences that are specific to certain screen sizes and SDKs. I've gone through the Android Providing Resources guide, but it seems that using alternative resources in the manner described there would still require me to create a separate resource directory for every screen-size-and-SDK combination and would require a lot of code duplication. Is there a nice, elegant solution to this problem that I'm missing?

Have you read the Settings guide? My app also has a lot of changes dynamically, both in 1) which headers / fragments to show, and 2) which prefs each fragment contains. For both issues you can use different resource versions, as you describe, or you can implement the differences in code.
For issue #1, you can either call loadHeadersFromResource directly, and have different headers resource files, or you can have code that does something similar. For example, my PreferencesActivity uses a separate PreferenceFragment subclass for each prefs section, and makes a decision at run time about which fragments (headers) to show:
#Override
public void onBuildHeaders(List<Header> targets) {
// Build a list of PreferenceFragment class objects to show now
List<Class<? extends PreferenceFragment>> fragmentClasses = ...;
// Create a Header for each fragment to return to Android
for (Class<? extends PreferenceFragment> fragmentClass: fragmentClasses) {
try {
PreferenceFragment fragment = fragmentClass.newInstance();
Header header = new Header();
header.fragment = fragmentClass.getName();
header.titleRes = fragment.getTitleId();
targets.add(header);
this.headers = targets;
} catch (Exception e) {
}
}
}
For issue #2, you can start with preferences from a common resource file, and then add the conditional ones in code:
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Load common prefs from an XML resource
addPreferencesFromResource(R.xml.preferences);
// Add conditional prefs in code
PreferenceScreen prefScreen = getPreferenceScreen();
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
Preference pref = ...; // create condition pref
prefScreen.addPreference(pref);
}
}
I actually add all prefs in code, common and conditional. However, I didn't see a way to create a PreferenceScreen from scratch, so I actually have an empty XML file that I load from resources, and then add all preferences in code. It works really well.

Dynamically create CheckBoxPreferences

I am currently building out a list of rows with checkboxes dynamically using content from a web service. However, this ListView will need to do pretty much what a PreferenceActivity would accomplish.
I don't know the number of rows as the content is dynamic so I can't create each CheckBoxPreference in XML. How do I go about building a PreferenceActivity that will display an unknown number rows with a CheckBoxPreference dynamically?

I think you're looking for something like this:
public class MyPreferenceActivity extends PreferenceActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
addPreferencesFromResource(R.xml.my_preference_activity);
//fetch the item where you wish to insert the CheckBoxPreference, in this case a PreferenceCategory with key "targetCategory"
PreferenceCategory targetCategory = (PreferenceCategory)findPreference("targetCategory");
//create one check box for each setting you need
CheckBoxPreference checkBoxPreference = new CheckBoxPreference(this);
//make sure each key is unique
checkBoxPreference.setKey("keyName");
checkBoxPreference.setChecked(true);
targetCategory.addPreference(checkBoxPreference);
}
}

Well #Jodes, actually both of you are right, but the correct way of doing this would be using a ListPreference.
I would use a entire programmatic approach, from my experience it's easier to be consistent; either create an entire XML layout via code, or via XML, but mixing the 2 can be weird and you cannot alter everything set via XML...
onCreate(){
this.setPreferenceScreen(createPreferenceHierarchy());
}
public PreferenceScreen createPreferenceHierarchy(){
PreferenceScreen root = getPreferenceManager().createPreferenceScreen(this);
// category 1 created programmatically
PreferenceCategory cat1 = new PreferenceCategory(this);
cat1.setTitle("title");
root.addPreference(cat1);
ListPreference list1 = new ListPreference(this);
list1.setTitle(getResources().getString(R.string.some_string_title));
list1.setSummary(getResources().getString(R.string.some_string_text));
list1.setDialogTitle(getResources().getString(R.string.some_string_pick_title));
list1.setKey("your_key");
CharSequence[] entries = calendars.getCalenders(); //or anything else that returns the right data
list1.setEntries(entries);
int length = entries.length;
CharSequence[] values = new CharSequence[length];
for (int i=0; i<length; i++){
CharSequence val = ""+i+1+"";
values[i] = val;
}
list1.setEntryValues(values);
cat1.addPreference(list1);
return root;
}//end method
However, using this approach you will run into the platform's limitations of not having a multiple select ListPreference, and you'll probably want to implement something else.
I found this solution, which works great. You'll have to read the comments to find clues about how to debug the code though...

You need a ListView for that, a PreferenceActivity. As discussed in this link, PreferenceActivity should only be used for actually saving preferences.
Instead you could either create a simple dialog with single or multiple choice options:
http://developer.android.com/guide/topics/ui/dialogs.html
Or use a ListView as in the API examples Google provides, they give a simple example:
http://hi-android.info/docs/resources/samples/ApiDemos/src/com/example/android/apis/view/List10.html

Use PreferenceFragmentCompat from Preference Compat Library
compile 'com.android.support:preference-v7:23.4.0'
Check this article for the implementation details https://medium.com/#arasthel92/dynamically-creating-preferences-on-android-ecc56e4f0789#.71ssvjses

Programmatically populating preferences with checkboxes

In my setting page I have a preference which fetches a list of toggle-able settings that I wanted to display as individual checkbox preferences.
I know that preferences.xml supports generating lists of preferences (looking at wi-fi settings page) but ListPreference only allows you to select one from the list.
I've been searching for how to generate preferences programmatically but have only managed to find how to change attributes of preferences that are already in the XML.

Here is a short example (assuming you are extending PreferenceActivity):
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
PreferenceScreen screen = getPreferenceManager().createPreferenceScreen(this);
PreferenceCategory category = new PreferenceCategory(this);
category.setTitle("category name");
screen.addPreference(category);
CheckBoxPreference checkBoxPref = new CheckBoxPreference(this);
checkBoxPref.setTitle("title");
checkBoxPref.setSummary("summary");
checkBoxPref.setChecked(true);
category.addPreference(checkBoxPref);
setPreferenceScreen(screen);
}

Programatically add a preference, with other preferences in xml file:
Other solutions didn't work for me because I ALSO had an xml with preferences. I'm not sure all these calls are necessary/redundant, but this works.
onCreate() method, class extends PreferenceActivity:
setContentView(R.layout.preferences);
addPreferencesFromResource(R.xml.preferences);
PreferenceScreen pScreen = getPreferenceManager().createPreferenceScreen(this);
CheckBoxPreference cb = new CheckBoxPreference(this);
cb.setKey("cb");
cb.setTitle("BLAH");
cb.setOrder(99); //not working...
pScreen.addPreference(cb);
setPreferenceScreen(pScreen);
addPreferencesFromResource(R.xml.preferences);
Sidenote: Since I needed to generate a dynamic checkbox list, it was best suited inside an inner PreferenceScreen. So I created this PreferenceScreen inside the xml, then dynamically generated the checkboxes inside this. This way the ordering didn't matter since all the 'new' dynamica checkboxes were inside this screen.

Try the below code.
CheckBoxPreference checkBoxPref = findPreference("your_key");
if (checkBoxPref != null)
{
checkBoxPref.setChecked(false);
}

Android: passing data between views

In my Android app, I have two custom view classes - PortraitClass and LandscapeClass. They both do the same thing. On running the app, the view class fetches some pictures from an SDCard and then maniputlates (skew etc) and displays them. The only difference between the two classes is that the layout of pictures is slightly different on the screen.
I have two display.xml files (one under layout folder and the other under layout-land). The one under the layout folder adds Portrait and the other adds the Landscape class.
On orientation change, I would like to send information (picture numbers and few bitmaps) from one class to another so I won't have to fetch all the bitmaps again and also so that I display the ones that were being displayed.
I find the parcelable thing kind of confusing. I tried following this_example, but I noticed that in onRestoreInstance, the Parcelable has null for the "mSuperState" and I get a classCastException # "SavedState ss = (SavedState)state". The integer (picture number) that I am trying to pass is there. I am not sure what I am doing wrong.

You could use a global singleton in the Application class. For example an "AssetManager" is available here:
public class YourApplication extends Application {
public AssetManager assetManager = new AssetManager();
#Override
public void onCreate()
{
super.onCreate();
}
}
You can then call it from another activity:
YourApplication application = ((YourApplication ) this.getApplication());
application.assetManager.someFunction();

Not sure if this is what you are looking for but my stuff always works in orientation change with onCreate(Bundle savedInstanceState). Mine is all text in edit text boxes though so I am not sure how it would work for you.
Also check this out about midway down under "Persisting State Information During Configuration Change"
http://www.devx.com/wireless/Article/40792/1954