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Wie kann ich auf Präferenzänderungen in einem PreferenceFragment achten?

Wie hier beschrieben, gebe ich PreferenceFragment ab und zeige es in einer Aktivität. In diesem Dokument wird erläutert, wie Sie auf Präferenzänderungen hier achten, jedoch nur, wenn Sie PreferenceActivity subclass. Wie höre ich auf Änderungen der Präferenzen, da ich das nicht mache?

Ich habe versucht, OnSharedPreferenceChangeListener in meinem PreferenceFragment zu implementieren, aber es scheint nicht zu funktionieren (onSharedPreferenceChanged scheint nie aufgerufen zu werden).

Dies ist mein Code bisher:

SettingsActivity.Java

public class SettingsActivity extends Activity
{
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);

        // Display the fragment as the main content.
        getFragmentManager().beginTransaction().replace(Android.R.id.content, new SettingsFragment()).commit();
    }
}

SettingsFragment.Java

public class SettingsFragment extends PreferenceFragment implements OnSharedPreferenceChangeListener
{
    public static final String KEY_PREF_EXERCISES = "pref_number_of_exercises";

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);

        // Load the preferences from an XML resource
        addPreferencesFromResource(R.xml.preferences);
    }

    @Override
    public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key)
    {
        //IT NEVER GETS IN HERE!
        if (key.equals(KEY_PREF_EXERCISES))
        {
            // Set summary to be the user-description for the selected value
            Preference exercisesPref = findPreference(key);
            exercisesPref.setSummary(sharedPreferences.getString(key, ""));
        }
    }
}

preferences.xml

<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:Android="http://schemas.Android.com/apk/res/Android" >

    <EditTextPreference
        Android:defaultValue="15"
        Android:enabled="true"
        Android:key="pref_number_of_exercises"
        Android:numeric="integer"
        Android:title="Number of exercises" />

</PreferenceScreen>

Ist PreferenceFragment auch der richtige Ort, um auf Präferenzänderungen zu hören, oder sollte ich dies innerhalb der Aktivität tun?

83

Ich glaube, Sie müssen nur die Listener in Ihrer PreferenceFragment registrieren/die Registrierung aufheben und es wird funktionieren.

@Override
public void onResume() {
    super.onResume();
    getPreferenceManager().getSharedPreferences().registerOnSharedPreferenceChangeListener(this);

}

@Override
public void onPause() {
    getPreferenceManager().getSharedPreferences().unregisterOnSharedPreferenceChangeListener(this);
    super.onPause();
}

Je nachdem, was Sie tun möchten, müssen Sie möglicherweise keinen Listener verwenden. Änderungen an den Einstellungen werden automatisch an SharedPreferences übergeben.

138
antew

Die Lösung von antew funktioniert gut, hier können Sie eine vollständige Präferenzaktivität für Android v11 sehen:

import Android.app.Activity;
import Android.content.SharedPreferences;
import Android.content.SharedPreferences.OnSharedPreferenceChangeListener;
import Android.os.Bundle;
import Android.preference.ListPreference;
import Android.preference.PreferenceFragment;

public class UserPreferencesV11 extends Activity  {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    // Display the fragment as the main content.
    getFragmentManager().beginTransaction().replace(Android.R.id.content,
            new PrefsFragment()).commit();
}

public static class PrefsFragment extends PreferenceFragment implements OnSharedPreferenceChangeListener {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // Load the preferences from an XML resource
        addPreferencesFromResource(R.xml.preferences);

        // set texts correctly
        onSharedPreferenceChanged(null, "");

    }

    @Override
    public void onResume() {
        super.onResume();
        // Set up a listener whenever a key changes
        getPreferenceScreen().getSharedPreferences().registerOnSharedPreferenceChangeListener(this);
    }

    @Override
    public void onPause() {
        super.onPause();
        // Set up a listener whenever a key changes
        getPreferenceScreen().getSharedPreferences().unregisterOnSharedPreferenceChangeListener(this);
    }

    @Override
    public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
        // just update all
        ListPreference lp = (ListPreference) findPreference(PREF_YOUR_KEY);
        lp.setSummary("dummy"); // required or will not update
        lp.setSummary(getString(R.string.pref_yourKey) + ": %s");

    }
}
}
25

Alle anderen Antworten sind richtig. Diese Alternative gefällt mir jedoch besser, da Sie sofort über die Preference-Instanz verfügen, die die Änderung verursacht hat.

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    Preference pref = findPreference(getString(R.string.key_of_pref));        
    pref.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener() {
        @Override
        public boolean onPreferenceChange(Preference preference, Object newValue) {
            // do whatever you want with new value

            // true to update the state of the Preference with the new value
            // in case you want to disallow the change return false
            return true;
        }
    });
}
13
Zsolt Safrany

Dies funktionierte für mich von PreferenceFragment.onCreate ()

OnSharedPreferenceChangeListener listener = 
    new SharedPreferences.OnSharedPreferenceChangeListener()
    {
        public void onSharedPreferenceChanged(SharedPreferences prefs, String key)
        {
         showDialog();
        }
    };
2
Gene Bo

Ein weiteres vollständiges Beispiel, damit Sie das gesamte Bild sehen können.

public class SettingsActivity extends AppCompatPreferenceActivity {


    /**
     * A preference value change listener that updates the preference's summary
     * to reflect its new value.
     */
    private static Preference.OnPreferenceChangeListener
            sBindPreferenceSummaryToValueListener =
            new Preference.OnPreferenceChangeListener() {

                @Override
                public boolean onPreferenceChange(Preference preference, Object value) {
                    String stringValue = value.toString();

                    if (preference instanceof ListPreference) {
                        // For list preferences, look up the correct display value in
                        // the preference's 'entries' list.
                        ListPreference listPreference = (ListPreference) preference;
                        int index = listPreference.findIndexOfValue(stringValue);

                        // Set the summary to reflect the new value.
                        preference.setSummary(
                                index >= 0
                                        ? listPreference.getEntries()[index]
                                        : null);

                    } else if (preference instanceof RingtonePreference) {
                        // For ringtone preferences, look up the correct display value
                        // using RingtoneManager.
                        if (TextUtils.isEmpty(stringValue)) {
                            // Empty values correspond to 'silent' (no ringtone).
                            preference.setSummary(R.string.pref_ringtone_silent);
                        } else {
                            Ringtone ringtone = RingtoneManager.getRingtone(
                                    preference.getContext(), Uri.parse(stringValue));
                            if (ringtone == null) {
                                // Clear the summary if there was a lookup error.
                                preference.setSummary(null);
                            } else {
                                // Set the summary to reflect the new ringtone display
                                // name.
                                String name = ringtone.getTitle(preference.getContext());
                                preference.setSummary(name);
                            }
                        }

                    } else {
                        // For all other preferences, set the summary to the value's
                        // simple string representation.
                        preference.setSummary(stringValue);
                    }
                    return true;
                }
            };

    /**
     * Helper method to determine if the device has an extra-large screen. For
     * example, 10" tablets are extra-large.
     */
    private static boolean isXLargeTablet(Context context) {
        return (context.getResources().getConfiguration().screenLayout
                & Configuration.SCREENLAYOUT_SIZE_MASK) >= Configuration.SCREENLAYOUT_SIZE_XLARGE;
    }

    /**
     * Binds a preference's summary to its value. More specifically, when the
     * preference's value is changed, its summary (line of text below the
     * preference title) is updated to reflect the value. The summary is also
     * immediately updated upon calling this method. The exact display format is
     * dependent on the type of preference.
     *
     * @see #sBindPreferenceSummaryToValueListener
     */
    private static void bindPreferenceSummaryToValue(Preference preference) {
        // Set the listener to watch for value changes.
        preference.setOnPreferenceChangeListener(sBindPreferenceSummaryToValueListener);

        // Trigger the listener immediately with the preference's current value.
        sBindPreferenceSummaryToValueListener.onPreferenceChange(preference,
                PreferenceManager
                        .getDefaultSharedPreferences(preference.getContext())
                        .getString(preference.getKey(), ""));
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setupActionBar();
    }

    /**
     * Set up the {@link Android.app.ActionBar}, if the API is available.
     */
    private void setupActionBar() {
        ActionBar actionBar = getSupportActionBar();
        if (actionBar != null) {
            // Show the Up button in the action bar.
            actionBar.setDisplayHomeAsUpEnabled(true);
        }
    }

    @Override
    public boolean onMenuItemSelected(int featureId, MenuItem item) {
        int id = item.getItemId();
        if (id == Android.R.id.home) {
            if (!super.onMenuItemSelected(featureId, item)) {
                NavUtils.navigateUpFromSameTask(this);
            }
            return true;
        }
        return super.onMenuItemSelected(featureId, item);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean onIsMultiPane() {
        return isXLargeTablet(this);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
    public void onBuildHeaders(List<Header> target) {
        loadHeadersFromResource(R.xml.pref_headers, target);
    }

    /**
     * This method stops fragment injection in malicious applications.
     * Make sure to deny any unknown fragments here.
     */
    protected boolean isValidFragment(String fragmentName) {
        return PreferenceFragment.class.getName().equals(fragmentName)
                || GPSLocationPreferenceFragment.class.getName().equals(fragmentName)
                || DataSyncPreferenceFragment.class.getName().equals(fragmentName)
                || NotificationPreferenceFragment.class.getName().equals(fragmentName);
    }

    ////////////////// NEW PREFERENCES ////////////////////////////

    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
    public static class GPSLocationPreferenceFragment extends PreferenceFragment {

        Preference prefGPSServerAddr, prefGPSASDID, prefIsGPSSwitch;

        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            addPreferencesFromResource(R.xml.pref_gps_location);
            setHasOptionsMenu(true);

            // Bind the summaries of EditText/List/Dialog/Ringtone preferences
            // to their values. When their values change, their summaries are
            // updated to reflect the new value, per the Android Design
            // guidelines.

            bindPreferenceSummaryToValue(findPreference("gpsServer_Addr"));
            bindPreferenceSummaryToValue(findPreference("gpsASD_ID"));


            prefGPSServerAddr = findPreference("gpsServer_Addr");
            prefGPSServerAddr.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener() {
                @Override
                public boolean onPreferenceChange(Preference preference, Object newValue) {

                    try {
                        // do whatever you want with new value

                    }
                    catch (Exception ex)
                    {
                        Log.e("Preferences", ex.getMessage());
                    }

                    // true to update the state of the Preference with the new value
                    // in case you want to disallow the change return false
                    return true;
                }
            });

            prefGPSASDID = findPreference("gpsASD_ID");
            prefGPSASDID.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener() {
                @Override
                public boolean onPreferenceChange(Preference preference, Object newValue) {

                    try {
                        // do whatever you want with new value

                    }
                    catch (Exception ex)
                    {
                        Log.e("Preferences", ex.getMessage());
                    }

                    // true to update the state of the Preference with the new value
                    // in case you want to disallow the change return false
                    return true;
                }
            });

            prefIsGPSSwitch = findPreference("isGPS_Switch");
            prefIsGPSSwitch.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener() {
                @Override
                public boolean onPreferenceChange(Preference preference, Object newValue) {

                    try {
                        // do whatever you want with new value

                    }
                    catch (Exception ex)
                    {
                        Log.e("Preferences", ex.getMessage());
                    }

                    // true to update the state of the Preference with the new value
                    // in case you want to disallow the change return false
                    return true;
                }
            });
        }

        @Override
        public boolean onOptionsItemSelected(MenuItem item) {
            int id = item.getItemId();
            if (id == Android.R.id.home) {
                boolean tabletSize = getResources().getBoolean(R.bool.isTablet);
                if (tabletSize) {
                    startActivity(new Intent(getActivity(), MainActivity.class));
                } else {
                    startActivity(new Intent(getActivity(), SettingsActivity.class));
                }
                return true;
            }
            return super.onOptionsItemSelected(item);
        }
    }

    ///////////////////////////////////////////////////////////////

    /**
     * This fragment shows notification preferences only. It is used when the
     * activity is showing a two-pane settings UI.
     */
    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
    public static class NotificationPreferenceFragment extends PreferenceFragment {
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            addPreferencesFromResource(R.xml.pref_notification);
            setHasOptionsMenu(true);

            // Bind the summaries of EditText/List/Dialog/Ringtone preferences
            // to their values. When their values change, their summaries are
            // updated to reflect the new value, per the Android Design
            // guidelines.
            bindPreferenceSummaryToValue(findPreference("notifications_new_message_ringtone"));
        }

        @Override
        public boolean onOptionsItemSelected(MenuItem item) {
            int id = item.getItemId();
            if (id == Android.R.id.home) {
                boolean tabletSize = getResources().getBoolean(R.bool.isTablet);
                if (tabletSize) {
                    startActivity(new Intent(getActivity(), MainActivity.class));
                } else {
                    startActivity(new Intent(getActivity(), SettingsActivity.class));
                }
                return true;
            }
            return super.onOptionsItemSelected(item);
        }
    }

    /**
     * This fragment shows data and sync preferences only. It is used when the
     * activity is showing a two-pane settings UI.
     */
    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
    public static class DataSyncPreferenceFragment extends PreferenceFragment {
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            addPreferencesFromResource(R.xml.pref_data_sync);
            setHasOptionsMenu(true);

            // Bind the summaries of EditText/List/Dialog/Ringtone preferences
            // to their values. When their values change, their summaries are
            // updated to reflect the new value, per the Android Design
            // guidelines.
            bindPreferenceSummaryToValue(findPreference("sync_frequency"));
        }

        @Override
        public boolean onOptionsItemSelected(MenuItem item) {
            int id = item.getItemId();
            if (id == Android.R.id.home) {
                boolean tabletSize = getResources().getBoolean(R.bool.isTablet);
                if (tabletSize) {
                    startActivity(new Intent(getActivity(), MainActivity.class));
                } else {
                    startActivity(new Intent(getActivity(), SettingsActivity.class));
                }
                return true;
            }
            return super.onOptionsItemSelected(item);
        }
    }
}

Ich habe kürzlich mein eigenes PreferenceScreen mit dem Preferences API, also dachte ich, ich würde mein eigenes vollständiges Beispiel beisteuern. Dies beinhaltet das Aktualisieren des Summary auf einen neuen/geänderten Wert sowie das Abhören und Reagieren auf Änderungen.

PS. Um Ihre letzte Frage zu beantworten: Um einen Standardwert für Summary beim erstmaligen Erstellen des PreferenceScreen anzuzeigen (vor jeder Änderung in der Wert), Sie könnten einfach das Android:summary zu einem Wert Ihrer Wahl, aus dem preferences.xml -Datei direkt - und sobald eine Änderung am Wert vorliegt , wird diese automatisch mithilfe des in meinem nachstehenden Beispiel enthaltenen Codes aktualisiert. Persönlich verwende ich eine kurze Erklärung des Preference als mein anfängliches Summary, das in meinem preferences.xml, und wenn der Wert zum ersten Mal geändert wird , wird einfach der aktuelle Wert als Summary von angezeigt dann auf ..

Wie auch immer , hier ist mein volles Beispiel:

SettingsFragment.Java

public class SettingsFragment extends PreferenceFragment {

public static final String PREF_NOTIFICATION_MODE = "pref_notificationMode";
private SharedPreferences.OnSharedPreferenceChangeListener preferenceChangeListener;

@Override
public void onCreate (@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    addPreferencesFromResource(R.xml.preferences);

    final SharedPreferences getPrefs = PreferenceManager.getDefaultSharedPreferences(this.getActivity());

    preferenceChangeListener = new SharedPreferences.OnSharedPreferenceChangeListener() {
        @Override
        public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {

            if (key.equals(PREF_NOTIFICATION_MODE)) {
                Preference notifModePref = findPreference(key);
                notifModePref.setSummary(sharedPreferences.getString(key, ""));

                //  DO SOMETHING ELSE HERE WHEN (PREF_NOTIFICATION_MODE) IS CHANGED
            }
        }
    };
}

@Override
public void onResume() {
    super.onResume();

    getPreferenceScreen().getSharedPreferences().registerOnSharedPreferenceChangeListener(preferenceChangeListener);

    Preference notifModePref = findPreference(PREF_NOTIFICATION_MODE);
    notifModePref.setSummary(getPreferenceScreen().getSharedPreferences().getString(PREF_NOTIFICATION_MODE, ""));

}

@Override
public void onPause() {
    getPreferenceScreen().getSharedPreferences().unregisterOnSharedPreferenceChangeListener(preferenceChangeListener);

    super.onPause();
}
}


Ich hoffe das hilft!
Jegliches positive Feedback wird sehr geschätzt, da ich bei StackOverflow ziemlich neu bin;)
Fröhliches Codieren!

0
Studio2bDesigns

Hier ist eine Möglichkeit, dies zu tun und mögliche Speicherlecks zu vermeiden:

@Override
public void onCreatePreferences(Bundle savedInstanceState, String rootKey) {
    addPreferencesFromResource(R.xml.pref_movies);

    SharedPreferences sharedPreferences = getPreferenceScreen().getSharedPreferences(); 

    //starts live change listener
    sharedPreferences.registerOnSharedPreferenceChangeListener(this);
}

@Override
public void onDestroyView () {
    super.onDestroyView(); 
//Unregisters listener here
    PreferenceManager.getDefaultSharedPreferences(getContext())
            .unregisterOnSharedPreferenceChangeListener(this);
}
0
Eaweb

Sie müssen nur die angegebene Prefernce-Klasse in Ihrer onResume() -Methode löschen. In meinem Fall habe ich die Klasse SwitchPreference verwendet, daher würde der Code wie folgt lauten: SettingsActivity.class

public static class PrivacyPreferenceFragment extends PreferenceFragment
{
    public SwitchPreference switchPreference;

    @Override
    public void onResume() {
        super.onResume();
        switchPreference = (SwitchPreference) findPreference("privacy_notice_check");
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        addPreferencesFromResource(R.xml.pref_privacy);
        setHasOptionsMenu(true);

    }

Verwenden Sie dann in der Aktivität, in der Sie den Wert PrefernceFragment verwenden möchten, einfach das Objekt SharedPreference, um die Werte aufzurufen und auszulösen.

0
Prajwal W