Develop Reference

Save App Preferences from PreferenceScreen when pressing back button

I'm trying to learn how to develop Android apps. I followed a video tutorial on YouTube, and it ended by adding a simple App Settings screen to the application.
However, there's one point that bothers me: when I press the back button on my phone's navigation bar, the changed settings aren't applied.
I have tried searching on Google, but none of the solutions I found have worked. The fact that I don't yet understand 100% of what's happening on the proposed solutions may also contribute to my difficulty on solving this one problem.
The behavior I expect from the app is that when I press the back button on the navigation bar, the changed settings should be applied.
For instance, I have a setting for dark background, which is controlled by a checkbox. The current behavior is: I check the setting for dark background. When I press the back button on the navigation bar, the setting isn't applied (I do have a method that loads the preferences on my MainActivity). What I want to happen is when I press the back button, the dark background is applied in this case.
From what I understand, I believe that overriding onBackPressed should do the trick, but I don't know what should be executed in order to properly apply the settings.
Here are the class and layout of my PreferenceScreen. Regarding the strings on the XML, they aren't actually hard-coded. I just copied the English values here to show the text that should appear on the interface.
public class AppPreferences extends AppCompatActivity
{
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_note_detail);
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
SettingsFragment settingsFragment = new SettingsFragment();
fragmentTransaction.add(android.R.id.content, settingsFragment, "SETTINGS_FRAGMENT");
fragmentTransaction.commit();
}
public static class SettingsFragment extends PreferenceFragment
{
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
addPreferencesFromResource(R.xml.app_preferences);
}
}
}
<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
<PreferenceCategory
android:title="General">
<EditTextPreference
android:title="Notebook"
android:summary="The title that will be used on the main action bar."
android:key="title"
android:defaultValue="Notebook" />
</PreferenceCategory>
<PreferenceCategory
android:title="Color">
<CheckBoxPreference
android:title="Dark Background"
android:summary="Is the main background color dark?"
android:key="background_color"
android:defaultValue="false" />
</PreferenceCategory>
</PreferenceScreen>

You will need to use
public class AppPreferences extends AppCompatActivity
{
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
//setContentView(R.layout.activity_note_detail);
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
SettingsFragment settingsFragment = new SettingsFragment();
fragmentTransaction.add(android.R.id.content, settingsFragment, "SETTINGS_FRAGMENT");
fragmentTransaction.commit();
}
public static class SettingsFragment extends PreferenceFragment
{
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
addPreferencesFromResource(R.xml.app_preferences);
Preference preference = findPreference("background_color");
preference.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener() {
#Override
public boolean onPreferenceChange(Preference preference, Object newValue) {
//do your action here
return false;
}
});
}
}
}
Or from other activity:
PreferenceManager.setDefaultValues(this, R.xml.your_setting_xml, false);
SharedPreferences settings = PreferenceManager.getDefaultSharedPreferences(this);
if (settings.getBoolean("background_color", true)) {
//do your action here
.........
Refer to this question also, (it has similar use case):
Checkbox Preference and Checking if its enabled or disable

Like #Chisko said, there isn't enough code in your question for us to be able to figure out your end goal - although I'm guessing you are wanting some form of persistent storage for your app to be able to save your app preferences. For this, you will want to use something in Android called SharedPreferences. This allows you to save simple data types to be accessed later.
Give that link a read, and then try saving/loading one simple piece of data. You'll want to load it from SharedPreferences on starting the activity (you can specify a default value if it hasn't been saved yet) and then you'll want to save the data in onBackPressed() as you said.
Best of luck and if you run into any issues, just comment here.

#Abdulhamid Dhaiban correctly points it out.
I'll add to your suggestion about overriding the onBackPressed() method.
If your "Up" button (top left <-) provides the correct result, then you can set the Back button to behave like the Up button by just adding the following code:
#Override
public void onBackPressed() {
super.onBackPressed();
NavUtils.navigateUpFromSameTask(this);
}
Hope it helps!

Show up-Button in actionBar in subscreen preferences

I've implemented my preferences like shown in the official guidelines.
I have a PreferenceActivity which creates the PreferenceFragment like this:
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
Bundle extras = getIntent().getExtras();
if (extras != null)
{
Bundle bundle = new Bundle();
_widgetID = extras.getInt(GlobalSettings.EXTRA_WIDGET_ID);
bundle.putInt(GlobalSettings.EXTRA_WIDGET_ID, _widgetID);
WidgetSettingsFragment fragment = new WidgetSettingsFragment();
fragment.setArguments(bundle);
getFragmentManager().beginTransaction().replace(android.R.id.content,
fragment).commit();
}
}
The PreferenceFragment loads the preferences from the resources and they contain a preference subscreen like this:
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
<!-- opens a subscreen of settings -->
<PreferenceScreen
android:key="button_voicemail_category_key"
android:title="#string/voicemail"
android:persistent="false">
<ListPreference
android:key="button_voicemail_provider_key"
android:title="#string/voicemail_provider" ... />
<!-- opens another nested subscreen -->
<PreferenceScreen
android:key="button_voicemail_setting_key"
android:title="#string/voicemail_settings"
android:persistent="false">
...
</PreferenceScreen>
<RingtonePreference
android:key="button_voicemail_ringtone_key"
android:title="#string/voicemail_ringtone_title"
android:ringtoneType="notification" ... />
...
</PreferenceScreen>
...
</PreferenceScreen>
This works well so far, but now I'd like to have an up-Button in the actionBar when the preferences subscreen is shown. Any idea how to accomplish that?
I have tried to set setDisplayHomeAsUpEnabled(true) in my activity but then the up-Button is only shown in the main preferences (where it should not) and not in the subscreen.
I'm wondering that even in the official docs the subscreen is shown without an active up-Button:
Link to the docs: Settings
Any help is really welcome

I finally got it to work :D. It's quite hacky but it works.
The problem is, that using subscreens in xml-layouts results in some 'code magic'.
A new activity/dialog is started for the subscreen and you don't have direct access to it.
To get access to the actionbar and the OnClickListener of the home/up-button you need to get a reference to your PreferenceScreen and get its parent Dialog in order to access the actionbar and its home/up button.
This is how it is done inside my PreferenceFragment:
#Override
public void onCreate(Bundle savedInstanceState)
{
...
final PreferenceScreen preferenceScreen = (PreferenceScreen) findPreference(getString(R.string.keyPrefScreenDynamicWidgetDetails));
preferenceScreen.setOnPreferenceClickListener(new OnPreferenceClickListener()
{
public boolean onPreferenceClick(Preference preference)
{
preferenceScreen.getDialog().getActionBar().setDisplayHomeAsUpEnabled(true);
final Dialog dialog = preferenceScreen.getDialog();
View homeBtn = dialog.findViewById(android.R.id.home);
if (homeBtn != null)
{
OnClickListener dismissDialogClickListener = new OnClickListener()
{
#Override
public void onClick(View v)
{
dialog.dismiss();
}
};
// Prepare yourselves for some hacky programming
ViewParent homeBtnContainer = homeBtn.getParent();
// The home button is an ImageView inside a FrameLayout
if (homeBtnContainer instanceof FrameLayout) {
ViewGroup containerParent = (ViewGroup) homeBtnContainer.getParent();
if (containerParent instanceof LinearLayout) {
// This view also contains the title text, set the whole view as clickable
((LinearLayout) containerParent).setOnClickListener(dismissDialogClickListener);
} else {
// Just set it on the home button
((FrameLayout) homeBtnContainer).setOnClickListener(dismissDialogClickListener);
}
} else {
// The 'If all else fails' default case
homeBtn.setOnClickListener(dismissDialogClickListener);
}
}
return true;
}
});
...
}
Following link gave me the final hints and code to solve my problem:
Action Bar Home Button not functional with nested PreferenceScreen

I do this per the Android docs in the "Supporting older versions with preference headers" section http://developer.android.com/guide/topics/ui/settings.html#BackCompatHeaders. Using the legacy PreferenceActivity, you specify a Preference in the xml that launches an intent to the same preference activity class. The activity checks the intent action and determines if it is nested or not (to show the up button) and which preference xml to inflate in the screen.
Of course, I intend to support older devices as well. I have found that the PreferenceFragment is only useful for large tablets that use preference headers.
To reuse preferences between phones and tablets I came up with this solution https://stackoverflow.com/a/20806812/1139784

To enable the up action do the following:
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setDisplayUseLogoEnabled(true);
this will give you the icon.
then add
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
// Respond to the action bar's Up/Home button
case android.R.id.home:
finish();
return true;
}
return super.onOptionsItemSelected(item);
}
you can alter this to go where you need to. As another option you can use the navigateUpTo(Intent intent) and the onSupportNavigateUpTo(Intent intent) methods and specify the intent you want to return to.

How do I programmatically add EditTextPreferences to my PreferenceFragment?

I am new to Android, so I need a little guidance on how to programmatically add EditTextPreference objects to my PreferenceFragment.
I am pulling in a list of values from a web service. I have saved them successfully to my SharedPreferences, and I use them to generate URLs (path portion).
I would like the users of my app to be able to edit these values, but after lots of searching on Google, it isn't clear to me how to programmatically add EditTextPreference objects to my PreferenceFragment.
Please note, my PreferenceFragment is working fine for the SharedPreferences values I hard code as names into the preference xml file (PreferenceScreen). I also know how to get my SharedPreferences, so don't worry about having to explain that portion to me.
I use addPreferencesFromResource in onCreate of my PreferenceFragment. Should I add them in the onCreateView? I was thinking I could get the PreferenceCategory and add them there? But again, I am not sure how to do that. I would really be grateful for the help!
// Code
PrefsFragment.java:
package com.example.lorddoineedhelp;
import android.os.Bundle;
import android.preference.PreferenceFragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class PrefsFragment extends PreferenceFragment {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
addPreferencesFromResource(R.xml.preferences);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = super.onCreateView(inflater, container, savedInstanceState);
// I am guessing I need to do something here?
return v;
}
}
XML File for PreferenceFragment:
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
<!-- Hard coded values -->
<PreferenceCategory
android:title="General">
<CheckBoxPreference
android:key="debug"
android:title="Debug"
android:summary="Enable Debug" />
</PreferenceCategory>
<PreferenceCategory android:title="Address">
<EditTextPreference
android:key="ipAddress"
android:title="IP Address"
android:summary="IP Address used for Image pings"
/>
<EditTextPreference
android:key="port"
android:title="Port"
android:summary="Port used for Image pings" />
</PreferenceCategory>
<!-- Where I want to add the values from my web service -->
<PreferenceCategory
android:title="Paths"
android:key="urlPaths">
</PreferenceCategory>
</PreferenceScreen>

You can add preferences, e.g. EditTextPreference, CheckBox, etc, programmatically in the "onCreate" method of the PreferenceFragment.
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Load "dummy" (empty) preferences from an XML resource
addPreferencesFromResource(R.xml.preferences_channelconfig);
PreferenceScreen screen = this.getPreferenceScreen(); // "null". See onViewCreated.
// Create the Preferences Manually - so that the key can be set programatically.
PreferenceCategory category = new PreferenceCategory(screen.getContext());
category.setTitle("Channel Configuration");
screen.addPreference(category);
CheckBoxPreference checkBoxPref = new CheckBoxPreference(screen.getContext());
checkBoxPref.setKey(channelConfig.getName() + "_ENABLED");
checkBoxPref.setTitle(channelConfig.getShortname() + "Enabled");
checkBoxPref.setSummary(channelConfig.getDescription());
checkBoxPref.setChecked(channelConfig.isEnabled());
category.addPreference(checkBoxPref);
}
The crucial step is the addPreferencesFromResource(...), with a dummy xml to attach an empty PreferenceScreen to the fragment. Without this, there is no "top-level Preference that is the root of a Preference hierarchy", thus this.getPreferenceScreen() returns Null.
The XML I used was just:
<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"
android:orderingFromXml="true">
</PreferenceScreen>
Hope that helps someone.

Here is the code to create a PreferenceFragment programmatically:
public class MyPreferenceFragment extends PreferenceFragment {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
PreferenceScreen screen = getPreferenceManager().createPreferenceScreen(getActivity());
setPreferenceScreen(screen);
EditTextPreference preference = new EditTextPreference(screen.getContext());
preference.setKey("EditTextPreference");
preference.setTitle("Edit Text Preference");
preference.setSummary("Click the preference to edit text.");
screen.addPreference(preference);
}
}

I don't know if it works in the onCreateView method but it does in the onViewCreated.
Here is my code (Inside a subclass of PreferenceFragment):
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
this.getPreferenceScreen().addPreference(new EditTextPreference(getActivity()));
}

Button listener not working in Preference fragment

I've created a subclass of PreferenceFragment that implements CompoundButton.OnCheckedChangeListener. I have one preference that contains a Switch (a subclass of CompoundButton). Here's the callback I've created for when the value of the switch changes:
#Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
mAppController.doSomething(isChecked);
Log.v("rose_tag", "hi");
}
I declare the preference in OnCreate as follows:
Switch mySwitch = (Switch) myView.findViewById(R.id.switch);
mySwitch.setEnabled(true);
mySwitch.setOnCheckedChangeListener(this);
The callback gets called when the view first opens (a breakpoint in the callback is hit), but no log prints, and the callback never gets called again, even when I switch the switch on and off. How can I make this callback work?
I also tried creating an inline anonymous listener. I also tried using a simple Button with an onClick listener, and that didn't work either.

I can see you are trying to use PreferenceFragment as any other normal fragment. However, you must to take in count the correct mechanism, one example is you cannot use all the widgets for making a preferences view for the user, you must use the Preference objects (see Preference subclasses).
Another example is that you must use addPreferencesFromResource(int) to inflate preferences from an XML resource.
Check both links above and this example.
I hope It helps you.

If you use the anwser from Jorge Gil, you will not be able to easily get a reference to the view you are declaring in the PreferenceScreen.
However you can easily get one of the preference Object which in that case is a SwitchPreference. So in your res/xml/preferences.xml add your switch preference:
<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen
xmlns:android="http://schemas.android.com/apk/res/android"
android:key="screen">
<SwitchPreference
android:key="switch_preference"
android:title="title"
android:summary="summary" />
</PreferenceScreen>
Then in your PreferenceFragment/PreferenceActivity's onCreate function add this:
addPreferencesFromResource(R.xml.preferences);
SwitchPreference switchPref = (SwitchPreference) findPreference("switch_preference");
switchPref.setOnPreferenceChangeListener(new OnPreferenceChangeListener() {
#Override
public boolean onPreferenceChange(Preference preference, Object newValue) {
Log.e(getClass().getSimpleName(),"onPreferenceChange:" + newValue);
return true;
}
});

ToggleButton change state on orientation changed

I have a CustomButton class (extends LinearLayout) where I inflate a layout which contains a ToggleButton (in reality this is more complex, but I simplified here the problem).
public class CustomButton extends LinearLayout {
private ToggleButton toggleOnOffButton;
public CustomButton(Context context, AttributeSet attrs) {
super(context, attrs);
LayoutInflater.from(context).inflate(R.layout.custom_button_layout, this);
}
#Override
protected void onFinishInflate() {
toggleOnOffButton = (ToggleButton) findViewById(R.id.toggle_on_off_button);
super.onFinishInflate();
}
public ToggleButton getToggleOnOffButton() {
return toggleOnOffButton;
}
}
custom_button_layout.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content">
<ToggleButton android:id="#+id/toggle_on_off_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textOff="Off"
android:textOn="On"
android:layout_alignParentRight="true"
/>
</RelativeLayout>
I have an activity where I inflate an layout with 2 CustomButton-s.
The on/off state of the first toggleButton is saved in shared preferences and I load the value from there in onCreate method.
public class FirstActivity extends Activity
{
private CustomButton customButton;
private ToggleButton toggleBut;
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
customButton = (CustomButton)findViewById(R.id.toggleButton);
toggleBut = customButton.getToggleOnOffButton();
boolean saved = loadPreferences("toggleBut");
toggleBut.setChecked(saved);
toggleBut.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
boolean checked = toggleBut.isChecked();
savePreferences("toggleBut", checked);
}
});
}
private void savePreferences(String key, boolean value){
SharedPreferences sharedPreferences = getPreferences(MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putBoolean(key, value);
editor.commit();
}
private boolean loadPreferences(String key){
SharedPreferences sharedPreferences = getPreferences(MODE_PRIVATE);
return sharedPreferences.getBoolean(key, true);
}
}
main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<com.example.example.cs.ssd.custom.CustomButton
android:id="#+id/toggleButton"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
<com.example.example.cs.ssd.custom.CustomButton
android:id="#+id/toggleButton2"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
</LinearLayout>
When I start the application the first toggleButton is ON. When I change the orientation of the screen, automatically the first toggleButton become Off, even saved has value true and is called toggleBut.setChecked(saved); and I think this has to do with the CutomButton I've created because if the main.xml layout contains only 1 CustomButton this problem does not reproduce.
I'm not sure what I'm doing wrong...
Here is the archive with the above code (as a project): archive

If you want your CustomButton to retain its current state after an orientation change simply override onSaveInstanceState() and onRestoreInstanceState().
A Solution
I ran through your code and noticed that toggleBut's state was being changed after onActivityCreated() but before onStart(). To avoid having any of these methods override your toggle settings, I simply moved these lines from onViewCreated():
boolean saved = loadPreferences("toggleBut");
toggleBut.setChecked(saved);
and put them in onResume(). Hope that helps!
Better Solution
Your ToggleButton setting are being overwritten when the system tries to restore the default saveInstanceState, probably in Fragment.onActivityCreated().
In CustomButton, override these functions like so:
#Override
protected Parcelable onSaveInstanceState() {
Bundle state = new Bundle();
state.putParcelable("default", super.onSaveInstanceState());
state.putParcelable("toggle", toggleOnOffButton.onSaveInstanceState());
return state;
}
#Override
protected void onRestoreInstanceState(Parcelable state) {
Bundle bundle = (Bundle) state;
super.onRestoreInstanceState(bundle.getParcelable("default"));
toggleOnOffButton.onRestoreInstanceState(bundle.getParcelable("toggle"));
};
Understand that the system will still change the ToggleButton states, without the one more thing. But let me try to explain what;s happening:
onActivityCreated(Bundle savedInstanceState) passes it's savedInstanceState to every layout element by calling 'onRestoreInstanceState(Bundle savedInstanceState)`.
onRestoreInstanceState() begins with the layout's root element first and traverses up the layout's hierarchy (in this case it sets the checked state of each ToggleButton last).
Since the default methods are clearly not working, we need to define our own save / restore method for the ToggleButtons. Otherwise any changes we make before the system calls onRestoreInstanceState() will be changed again by the system...
So, lastly we will exclude the ToggleButtons from this default behavior by adding the following line to CustomButton.onFinishInflate():
toggleOnOffButton.setSaveEnabled(false);
Voila, your CustomButtons automatically retain their state.