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DialogPreference is not saving the preference when I expect it to?

I have written a bare bones standard DialogPreference which is working fine, except that it is not saving the preference to default shared preferences when I expected it to.
1) open the app, and main activity shows value of foo from default shared preferences = 1
2) go to settings
3) click on foo setting which opens my DialogPreference and shows value = 1
4) enter value 3
5) close my DialogPreference using Ok button
***** default shared preferences foo should now be 3
6) click on foo setting which opens my DialogPreference and shows value = 1
***** so my DialogPreference didn't save the preference to default shared preferences?
7) cancel dialog
8) go back to main activity which shows value of foo from default shared preferences = 3
***** so my DialogPreference did save the preference to default shared preferences
9) go to settings
10) click on foo setting which opens my DialogPreference and shows value of 3
Why isn't the value of default shared preferences foo = 3 at step (6)?
It seems that the preference is only being saved to default shared preferences when the flow returns to the main activity from the settings list, which is counter intuitive to saving the preference in the onDialogClosed method of DialogPreference.
MyDialogPreference
public class MyDialogPreference extends DialogPreference
{
private static final String DEFAULT_VALUE = "0";
private String value = DEFAULT_VALUE;
private EditText editText;
public MyDialogPreference(Context context, AttributeSet attrs)
{
super(context, attrs);
setDialogLayoutResource(R.layout.constrained_integer_preference);
}
#Override
public void onBindDialogView(View view)
{
super.onBindDialogView(view);
editText = (EditText) view.findViewById(R.id.edit);
editText.setText("" + value);
}
#Override
protected void onDialogClosed(boolean positiveResult)
{
if (positiveResult)
{
persistString(editText.getText().toString());
}
super.onDialogClosed(positiveResult);
}
#Override
protected Object onGetDefaultValue(TypedArray typedArray, int index)
{
return typedArray.getString(index);
}
#Override
protected void onSetInitialValue(boolean restorePersistedValue, Object defaultValue)
{
if (restorePersistedValue)
{
value = getPersistedString(DEFAULT_VALUE);
}
else
{
value = (String) defaultValue;
if (shouldPersist())
{
persistString(value);
}
}
}
}
EDIT: So it appears that the preference I am handling with my DialogPreference has no key, which is causing all the problems. But I have specified the key in the preferences.xml file for this DialogPreference. I have tried everything to force the key to be recognised but nothing is working.
Can anyone tell me how I get a DialogPreference to receive the android:key from the preferences.xml file to work?
preferences.xml
<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto">
<org.mycompany.myproject.MyDialogPreference
android:defaultValue="11"
android:dialogLayout="#layout/my_preference"
android:inputType="number"
android:key="MY_KEY"
android:selectAllOnFocus="true"
android:singleLine="true"
android:summary="summary"
android:title="My Preference" />
</PreferenceScreen>

You'd have to implement the OnPreferenceChangeListener and/or call to notifyChanged().
Unless you'd provide the code of that DialogPreference, it's difficult to reproduce the issue.

At some point I always feel like I'm hacking Android, and this is definitely a hack.
Initially I thought the problem I was fighting was that the framework ignores my android:key, because getKey() returns an empty string, but that can't be true because it gets the persistent value when it starts the PreferenceScreen, and saves my changed values to shared preferences when I close the DialogPreference.
So it seems the problem I am fighting is that the framework reads the preferences persistent values in to internal members, and then uses the internal members until the flow returns out of the preferences framework, without refreshing them after a DialogPreference has closed.
But I have finally found a way of getting the PreferenceScreen to refresh the preferences persistent values it holds in it's internal members. Although it's not really a refresh, it's a hack.
So what I do is basically throw away the PreferenceScreen and create a new one. I do this by adding the following code to my SettingsFragment.onCreate method directly before addPreferencesFromResource(R.xml.preferences).
SharedPreferences.OnSharedPreferenceChangeListener prefListener = (prefs, key) ->
{
setPreferenceScreen(null);
addPreferencesFromResource(R.xml.preferences);
};
PreferenceManager.getDefaultSharedPreferences(getActivity().getApplicationContext()).registerOnSharedPreferenceChangeListener(prefListener);
This is probably bad. I have tested it, repeatedly, though not thouroghly, and have not witnessed any adverse effects so far.
So with this hack, I can now repeatedly open a DialogPreference from the PreferenceScreen, save a new value, then go back in to the DialogPreference with the previously updated value.
I don't believe my hack is the intended way of achieving this outcome, but after days of searching the source code and google for answers, I have not found anything else.
I am leaving this answer here for anyone else that faces the same problem and is brave enough to try my hack. I'll update the answer if (and probably when) I find any problems with the hack.
Better yet, if anyone else can provide a preferred solution, pointing out what I have done wrong that caused the problem, please do.
EDIT: After working for so long, that hack eventually broke, and consistently.
But while removing the hack, I approached the problem with a fresh mind, and using the fact that I determined the dialog is getting the preference key, I used this fix for the problem, which is working perfectly.
I added this line of code to the start of onBindDialogView
value = getSharedPreferences().getString(getKey(), "-1");
Which makes the calls to onGetDefaultValue and onSetInitialValue redundant, but they just don't work as intended, at least not for me.
EDIT:
omg, I hate this!
I did not notice that during an earlier refactor the line of code that updates the DialogPreference internal value in onDialogClosed was removed.
It's usually something simple, and with everything else I was checking, I missed that small change.
I only just noticed it during a code review on the repo, and now I feel silly. So no additional code was required in the end.

How do I set showSeekBarValue to true in Android?

I'm writing my first Android app and it involves a preference where you set an amount of minutes, from 0 to 60. I've used a SeekBarPreference, and it shows up as a simple slider which you can indeed slide around to edit the value. The preference works fine.
I would like to show the selected value next to the SeekBar (or somewhere in the vicinity), as there by default is no way for the user to see what they've actually selected. There are lots of questions on Stack Overflow about similar sliders and preferences, but since version 25.1.0, released last December, there is SeekBarPreference, which has just what I need:
The seekbar value view can be shown or disabled by setting showSeekBarValue attribute to true or false, respectively.
But among the public methods listed below, there is no method for setting showSeekBarValue? There is a method for setting the adjustable attribute, setAdjustable(boolean adjustable), however?
Ideally I'd just write android:showSeekBarValue="true" in my SeekBarPreference tag in preferences.xml, but that (obviously) doesn't work.
So in a nutshell: how do I set showSeekBarValue to true?

In the app's build.gradle, I had to add
implementation 'com.android.support:preference-v7:26.+
Then, modify the PreferenceScreen's xml to include an app namespace:
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto">
Finally, inside the xml, you can add
<SeekBarPreference
android:key="..."
android:title="..."
android:max="100"
android:min="0"
android:defaultValue="30"
android:dependency="..."
app:showSeekBarValue="true"
/>
This compiles without errors. To be fair, this is not a complete answer, because no value is shown in my case, even after these steps. But formally it does let you set the value in some way.

You need to use PreferenceScreen from android.support.v7.preference
<android.support.v7.preference.PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto">
<SeekBarPreference
android:key="size"
android:title="Size"
android:summary="size of progressBar in dp's"
android:max="100"
app:showSeekBarValue="true"
android:defaultValue="25" />
</android.support.v7.preference.PreferenceScreen>
and also PreferenceFragmentCompat from android.support.v7.preference
import android.support.v7.preference.PreferenceFragmentCompat
class SettingsFragment: PreferenceFragmentCompat() {
override fun onCreatePreferences(savedInstanceState: Bundle?, rootKey: String?) {
addPreferencesFromResource(R.xml.preferences)
}
}

Two problems with the Activity settings in Android

I have two roughly connected issues in my new Android app regarding the Settings. The former is the need to retrieve the information from the preferences without displaying the specific setting activity by performing some:
addPreferencesFromResource(R.xml.preferences);
in another activity.
Is it possible to do it or how else may I retrieve the data without displaying the activity, or is it possible to start the activity without displaying it?
The latter more distressing one is that even in the SettingActivity, when I call that function I recently started getting a crash complaining:
java.lang.ClassCastException: java.lang.Float cannot be cast to java.lang.String
Like if something internal were set somehow expecting something. What may I do and in particular how may I reset this sort of hidden structure?
This is my xml file: if I just keep the entries in the former category it does not crash, if I add any field in the latter it does:
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
<PreferenceCategory
android:title="#string/switches"
android:key="switches">
<EditTextPreference
android:key="night_switch_start"
android:summary="#string/ext_night_switch_start"
android:defaultValue="22"
android:title="#string/night_switch_start" />
<EditTextPreference
android:key="day_switch_start"
android:summary="#string/ext_day_switch_start"
android:defaultValue="6"
android:title="#string/day_switch_start"/>
</PreferenceCategory>
<PreferenceCategory
android:title="#string/tokens"
android:key="tokens">
<EditTextPreference
android:key="token_day"
android:summary="#string/ext_token_day"
android:defaultValue="3"
android:title="#string/token_day" />
</PreferenceCategory>
</PreferenceScreen>
Thanks, Fabrizio

For you first question, you can retrieve a preference saved in a PreferenceActivity by calling PreferenceManager#getDefaultSharedPreferences(Context). This is a static method, so you can have in your Activity something like:
SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(this);
About your second question, I'm not sure what is happening. Try cleaning the project before you run it again.

I answer here to be able to show my code better: this is the first summarizing part of the xml file I suspect might have problems:
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
<PreferenceCategory
android:title="#string/switches"
android:key="switches">
<EditTextPreference
android:key="night_switch_start"
android:summary="#string/ext_night_switch_start"
android:defaultValue="22"
android:inputType="numberDecimal"
android:title="#string/night_switch_start" />
<EditTextPreference
android:key="day_switch_start"
android:summary="#string/ext_day_switch_start"
android:defaultValue="6"
android:inputType="numberDecimal"
android:title="#string/day_switch_start"/>
</PreferenceCategory>
<PreferenceCategory
android:title="#string/tokens"
android:key="switches">
<EditTextPreference
android:key="token_day"
android:summary="#string/ext_token_day"
android:defaultValue="3"
android:inputType="numberDecimal"
android:title="#string/token_day" />
</PreferenceCategory>
</PreferenceScreen>
My code is very simple: the crashing setting part is the following.
public class SettingsActivity extends PreferenceActivity {
private static final String LOG_TAG = "preferences";
public static class SettingsFragment extends PreferenceFragment implements OnSharedPreferenceChangeListener{
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Load the preferences from an XML resource
addPreferencesFromResource(R.xml.preferences);
}
...
}
While the code loading the string and finding "mostly" empty strings is:
sharedPref= PreferenceManager.getDefaultSharedPreferences(Dashboard.dashboard);
startDayTime=Integer.parseInt(sharedPref.getString("day_switch_start", "")); //correct value
startNightTime=Integer.parseInt(sharedPref.getString("night_switch_start", "")); //empty string thereafter rising an exception.
Also, when I tried leaving just the first two EditText, so not to have the crash, the Setting activity had the correct value for day_switch_start and again an empty string in the night_switch_start field.
When I do getAll() I get the correct values:
{start_night_time=6, day_switch_start=6, notifications_new_message_ringtone=content://settings/system/notification_sound, notifications_new_message=true, second_rate_limit=24.0, third_rate_fare=1.6, token_day=6.0, token_night=6.0, night_switch_start=22, token_holiday=6.0, start_day_time=6, start_night_switch=John Smith, example_checkbox=true, example_text=John Smith, notifications_new_message_vibrate=false, example_list=-1, first_rate_fare=1.1, first_rate_limit=11.0, max_speed_for_time=20.0, sync_frequency=180, second_rate_fare=1.3, timed_fares=27.0, cooperative=}
Yet, when I try to get the value of them either with:
startDayTime=Integer.parseInt(sharedPref.getString("night_switch_start", "")); or
startNightTime=sharedPref.getInt("night_switch_start", 0);
I retrieve an empty string in both cases.

Half of the answer: clearing the cache of the phone removes all the funny fields and does not crash any longer the setting activity, nor the loading of its values by:
startNightTime=Integer.parseInt(sharedPref.getString("night_switch_start", ""));
The old form:
startNightTime=sharedPref.getInt("night_switch_start", 0);
still crashes, notwithstanding the values seem numeral. Not a big deal, though.
The unanswered problem is how to load the settings from the xml file without entering the SettingsActivity performing:
addPreferencesFromResource(R.xml.preferences);
Is it possible to run the function from outside that activity or is it possible to start the activity without visualizing it to the user?

Custom “Select All” checkbox in ListPreference

I have implemented a custom ListPreference and managed to load a list of items along with checkboxes for each without an issue. However, I need to add a “Select All” checkbox on top in order to select all list of items. How would I achieve this with the following source I have implemented?
The layout:
<PreferenceScreen
xmlns:android="http://schemas.android.com/apk/res/android">
<PreferenceCategory
android:title="#string/Title_LOCATIONS">
<com.gm.settings.LocationsListPreference
android:defaultValue="null"
android:key="list_locations"
android:title="#string/LocationsListPreference_title"
android:dialogTitle="#string/LocationsListPreference_title"
android:summary="#string/LocationsListPreference_summary"
/>
The class:
public class LocationsListPreference extends ListPreference {
}
I have implemented the class by following a tutorial and it works fine. But it uses a default layout i think and if I were to add this addition checkbox, how would I achieve this?
Update:
I want to know as to how i can add the "Select All" checkbox to the layout? Or should i create a custom layout? Please provide a sample code. (Because i feel the way it is right now, i dont have the control over this checkbox)

What you could do is add a CheckBoxPreference in your PreferenceCategory and attach to it a OnPreferenceChangedListener that sets all of the values to being checked.
An example could probably look a little something like this:
<CheckBoxPreference
android:key="select_all"
android:defaultValue="false"
android:title="Select All"
/>
<com.gm.settings.LocationsListPreference
android:defaultValue="null"
android:key="list_locations"
android:title="#string/LocationsListPreference_title"
android:dialogTitle="#string/LocationsListPreference_title"
android:summary="#string/LocationsListPreference_summary"
/>
And then in your PreferenceFragment (or PreferenceActivity), you would have the following:
SharedPreferences shareprefs = getPreferenceManager().getSharedPreferences();
LocationsListPreference listPreference = getPreference("list_locations");
CheckBoxPreference selectAll = getPreference("select_all");
selectAll.setOnPreferenceChangeListener(new OnPreferenceChangeListener()
{
public boolean onPreferenceChanged(Preference preference, Object newValue)
{
//Do something with your listPreference and/or your sharedPrefs
}
}
Hope this helps, and if you get to a road block, I think this post does a slightly better job at explaining some of the concepts. Good luck!

Found a stackoverflow post which might help others if they come across this kind of implementation:
You can build your custom ListPreference layout.
Cheers!

Leaving PreferenceActivity, calling Activity still reads old preference?

I feel I'm missing something obvious, but search took me to several different hits, all of which don't directly access my odd issue.
Have an app with a main activity and a preference activity. Add to that a 'preference' class, which simplifies reading and setting preferences. The main activity has an option menu to get to the preference activity:
Preferences class (included for relevance, same thing happens if I don't use this class to read settings).
public class Preferences
{
public static SharedPreferences getPrefs(Context context)
{
SharedPreferences retCont = PreferenceManager.getDefaultSharedPreferences(context);
return retCont;
}
/* Map Page: Show Satellite */
public static boolean getMapShowSatellite(Context context)
{
return Preferences.getPrefs(context).getBoolean(Preferences.getString(context, R.string.option_showSatellite), false);
}
public static void setMapShowSatellite(Context context, boolean newValue)
{
Editor prefsEditor = Preferences.getPrefs(context).edit();
prefsEditor.putBoolean(Preferences.getString(context, R.string.option_showSatellite), newValue);
prefsEditor.commit();
}
}
PreferencesActivity:
public class AppSettings extends PreferenceActivity
{
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
addPreferencesFromResource(R.xml.app_preferences);
ListPreference stationType = (ListPreference)this.findPreference(this.getString(R.string.option_filterStationType));
stationType.setOnPreferenceChangeListener(this.stationOrderEnable());
}
[...]
}
The last two lines hook up an event to enable/disable other preferences based on one's selection. That works, as expected.
The simple main activity, and related functions:
public class MainMapScreen extends MapActivity
{
private void launchSettings()
{
Intent prefsIntent = new Intent(this.getApplicationContext(), AppSettings.class);
this.startActivity(prefsIntent);
}
#Override
protected void onResume()
{
super.onResume();
Preferences.getMapShowSatellite(); // <-- Returns previous value.
// Re-start the MyLocation Layer from tracking.
this._mapView.requestLayout();
}
[...]
}
Okay, so what happens is, let's say we run the app. At app load, the getMapShowSatellite() returns True. Go into the PreferenceActivity, and change that option to False. Exit the PreferenceActivity by hitting the Back button. At this time, the main activity's onResume() is called. Getting the getMapShowSatellite() at this point returns the previous setting of True. Exiting and relaunching the app will then finally return the False expected.
I'm not calling .commit() manually - and don't think I need to, sicne the setting IS saving, I'm just not getting update values.
What'm I missing? :)
--Fox.
Edit 2: Small update. I thought the issue may be the static calls - so temporarily I changed over my Preferences class (above) to be a instantiated class, no more static. I also added the following code to my onResume() call in the main activity:
//Try reloading preferences?
SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(this);
String test = sp.getString(Preferences.OPTION_FILTERSTATIONTYPE, "---");
Log.e("BMMaps", test);
What is logged at this point, from leaving the PreferenceActivity, is the old setting. Manually reading the preferences file shows me that the .xml file is getting updated with the user's new setting.
Since it's not obvious, I am hooked into Google's Maps API. Because of this, I had to specify two ifferent processes - one for the Main activity (this one) and another for an activity not related to this issue. All other activities, including the PreferencesActivity have no specified android:process="" in their definition.
Edit 3:
As requested, here's the data preferences file:
<?xml version='1.0' encoding='utf-8' standalone='yes' ?>
<map>
<string name="com.tsqmadness.bmmaps.filterStationType">V-?</string>
<boolean name="com.tsqmadness.bmmaps.deviceHasLocation" value="false" />
</map>
And here is the Preference storage XML file:
<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
<PreferenceCategory android:title="Map Options">
<CheckBoxPreference android:key="com.tsqmadness.bmmaps.mapShowSatellite" android:order="1" android:summary="Whether or not to show satellite imagery on the map." android:summaryOff="Standard road map will be shown." android:summaryOn="Satellite imagery will be show." android:title="Show Satellite Layer?" />
<CheckBoxPreference android:key="com.tsqmadness.bmmaps.mapShowScale" android:order="2" android:summary="Whether or not to show the distance bar on the map." android:summaryOff="The distance bar will not be shown on the map." android:summaryOn="The distance bar will be shown on the map." android:title="Show Map Scale?" />
<CheckBoxPreference android:defaultValue="false" android:key="com.tsqmadness.bmmaps.useMetric" android:order="3" android:summary="Whether to use Metric os SI values." android:summaryOff="SI units (mi/ft) will be shown." android:summaryOn="Metric units (km/m) will be shown." android:title="Use Metric?" />
<ListPreference android:dialogTitle="Station Load Delay" android:entries="#array/static_listDelayDisplay" android:entryValues="#array/static_listDelayValues" android:key="com.tsqmadness.bmmaps.mapBMDelay" android:negativeButtonText="Cancel" android:order="4" android:positiveButtonText="Save" android:summary="The delay after map panning before staions are loaded." android:title="Delay Before Loading" />
</PreferenceCategory>
<PreferenceCategory android:title="Control Station Filter">
<ListPreference android:dialogTitle="Station Type" android:entries="#array/static_listStationTypeDisplay" android:entryValues="#array/static_listStationTypeValues" android:key="com.tsqmadness.bmmaps.filterStationType" android:negativeButtonText="Cancel" android:positiveButtonText="Save" android:summary="The station type to filter on." android:title="Station Type" android:order="1" />
<ListPreference android:dialogTitle="Select Station Order" android:entries="#array/static_listStationHOrderDisplay" android:entryValues="#array/static_listStationHOrderValues" android:key="com.tsqmadness.bmmaps.filterStationOrder" android:negativeButtonText="Cancel" android:positiveButtonText="Save" android:summary="Station Order to filter by." android:title="Station Order" android:order="2" />
<ListPreference android:dialogTitle="Select Station Stability" android:entries="#array/static_listStationStabilityDisplay" android:entryValues="#array/static_listStationStabilityValues" android:key="com.tsqmadness.bmmaps.filterStationStability" android:negativeButtonText="Cancel" android:positiveButtonText="Save" android:summary="Station stability to filter by." android:title="Station Stability" android:order="3" />
<CheckBoxPreference android:key="com.tsqmadness.bmmaps.filterNonPub" android:summaryOff="Non-Publishable stations will not be shown." android:defaultValue="false" android:summaryOn="Non-Publishable stations will be shown on the map." android:order="4" android:title="Show Non-Publishable" />
</PreferenceCategory>
<Preference android:key="temp" android:title="Test" android:summary="Test Item">
<intent android:targetClass="com.tsqmadness.bmmaps.activities.MainMapScreen" android:targetPackage="com.tsqmadness.bmmaps" />
</Preference>
</PreferenceScreen>
When changing the filterStationType parameter, and hitting the back button out of PreferenceActivity changes the preferences file from the above from V-? to H-?, as it should. However, reading the value from the SharedPreferences on the main activity still gives the V-?, until app restart. Ah, also, I have a OnPreferenceChangeListnener() in the PreferenceActivity, and that is called when the value changes.
Final Edit: Apparently, it's the use of named android:process for the given activity. This is needed for Google maps API to allow two separate MapActivitys in the same app use different settings. If the PreferenceActivity is moved to the same named-process, then the code above, reading the setting in the onResume() returns the correct value.

Since everything checks out, my guess is that you have a typo, or incorrect or undefined, key in your PreferenceActivity's app_preferences.xml file for the key R.string.option_showSatellite (whatever that string is). This would result in two keys with [unbeknownst to you] different names that you think point to the same value. Really, the prefs activity is using one key and your Preference class is using the other -- resulting in two different keys and two different values.
Double check your keys. Make sure you are not also using the literal "R.string.options_showSatellite" as the key in the xml file, but rather, the actual string. If you want to use the localized version then #string/options_showSatellite would work for the key. However, keys need not be localized.
If you're curious, this can be double checked by opening the preference file that is created by the preference manager in your app's data directory in a standard text editor.

onResume you have to get a fresh reference to SharedPreferences, otherwise you're just using an object that is already in memory (and has your old values)
EDIT:
Rather than down-voting answers that you don't understand, why not ask for clarification instead?
What I mean is that you should pull your Prefs the correct way (rather than how you're doing it)...
SharedPreferences sp = getSharedPreferences(getPackageName(), MODE_PRIVATE);
And then see what happens.