Use a prefences file per device/plugin combo

Cleanup global plugin preferences after migration to per device preferences

src/org/kde/kdeconnect/BackgroundService.java

@@ -16,7 +16,7 @@
  *
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>. 
- */
+*/
 
 package org.kde.kdeconnect;
 
@@ -24,7 +24,6 @@ import android.app.Notification;
 import android.app.NotificationManager;
 import android.app.PendingIntent;
 import android.app.Service;
-import android.bluetooth.BluetoothClass;
 import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
@@ -33,9 +32,12 @@ import android.net.ConnectivityManager;
 import android.os.Binder;
 import android.os.Build;
 import android.os.IBinder;
+import android.preference.PreferenceManager;
 import android.text.TextUtils;
 import android.util.Log;
 
+import androidx.core.app.NotificationCompat;
+
 import org.kde.kdeconnect.Backends.BaseLink;
 import org.kde.kdeconnect.Backends.BaseLinkProvider;
 import org.kde.kdeconnect.Backends.LanBackend.LanLinkProvider;
@@ -53,14 +55,12 @@ import org.kde.kdeconnect_tp.R;
 
 import java.util.ArrayList;
 import java.util.HashSet;
+import java.util.Iterator;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.locks.Lock;
 import java.util.concurrent.locks.ReentrantLock;
 
-import androidx.core.app.NotificationCompat;
-
-
 //import org.kde.kdeconnect.Backends.BluetoothBackend.BluetoothLinkProvider;
 
 public class BackgroundService extends Service {
@@ -280,6 +280,7 @@ public class BackgroundService extends Service {
         initializeSecurityParameters();
         NotificationHelper.initializeChannels(this);
         loadRememberedDevicesFromSettings();
+        migratePluginSettings();
         registerLinkProviders();
 
         //Link Providers need to be already registered
@@ -290,6 +291,29 @@ public class BackgroundService extends Service {
         }
     }
 
+    private void migratePluginSettings() {
+        SharedPreferences globalPrefs = PreferenceManager.getDefaultSharedPreferences(this);
+
+        for (String pluginKey : PluginFactory.getAvailablePlugins()) {
+            if (PluginFactory.getPluginInfo(pluginKey).supportsDeviceSpecificSettings()) {
+                Iterator<Device> it = devices.values().iterator();
+
+                while (it.hasNext()) {
+                    Device device = it.next();
+                    Plugin plugin = PluginFactory.instantiatePluginForDevice(getBaseContext(), pluginKey, device);
+
+                    if (plugin == null) {
+                        continue;
+                    }
+
+                    plugin.copyGlobalToDeviceSpecificSettings(globalPrefs);
+                    if (!it.hasNext()) {
+                        plugin.removeSettings(globalPrefs);
+                    }
+                }
+            }
+        }
+    }
 
     public void changePersistentNotificationVisibility(boolean visible) {
         NotificationManager nm = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);

src/org/kde/kdeconnect/Device.java

@@ -33,6 +33,12 @@ import android.preference.PreferenceManager;
 import android.util.Base64;
 import android.util.Log;
 
+import androidx.annotation.AnyThread;
+import androidx.annotation.Nullable;
+import androidx.annotation.WorkerThread;
+import androidx.core.app.NotificationCompat;
+import androidx.core.content.ContextCompat;
+
 import org.kde.kdeconnect.Backends.BaseLink;
 import org.kde.kdeconnect.Backends.BasePairingHandler;
 import org.kde.kdeconnect.Helpers.NotificationHelper;
@@ -57,11 +63,6 @@ import java.util.Vector;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.CopyOnWriteArrayList;
 
-import androidx.annotation.AnyThread;
-import androidx.annotation.WorkerThread;
-import androidx.core.app.NotificationCompat;
-import androidx.core.content.ContextCompat;
-
 public class Device implements BaseLink.PacketReceiver {
 
     private final Context context;
@@ -712,11 +713,13 @@ public class Device implements BaseLink.PacketReceiver {
     // Plugin-related functions
     //
 
+    @Nullable
     public <T extends Plugin> T getPlugin(Class<T> pluginClass) {
         Plugin plugin = getPlugin(Plugin.getPluginKey(pluginClass));
         return (T) plugin;
     }
 
+    @Nullable
     public Plugin getPlugin(String pluginKey) {
         return plugins.get(pluginKey);
     }

src/org/kde/kdeconnect/Plugins/Plugin.java

@@ -22,10 +22,17 @@ package org.kde.kdeconnect.Plugins;
 
 import android.app.Activity;
 import android.content.Context;
+import android.content.SharedPreferences;
 import android.content.pm.PackageManager;
 import android.graphics.drawable.Drawable;
 import android.os.Build;
 
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.annotation.StringRes;
+import androidx.core.content.ContextCompat;
+import androidx.fragment.app.DialogFragment;
+
 import org.kde.kdeconnect.Device;
 import org.kde.kdeconnect.NetworkPacket;
 import org.kde.kdeconnect.UserInterface.AlertDialogFragment;
@@ -34,19 +41,37 @@ import org.kde.kdeconnect.UserInterface.PermissionsAlertDialogFragment;
 import org.kde.kdeconnect.UserInterface.PluginSettingsFragment;
 import org.kde.kdeconnect_tp.R;
 
-import androidx.annotation.StringRes;
-import androidx.core.content.ContextCompat;
-import androidx.fragment.app.DialogFragment;
-
 public abstract class Plugin {
     protected Device device;
     protected Context context;
     protected int permissionExplanation = R.string.permission_explanation;
     protected int optionalPermissionExplanation = R.string.optional_permission_explanation;
+    @Nullable
+    protected SharedPreferences preferences;
 
-    public final void setContext(Context context, Device device) {
+    public final void setContext(@NonNull Context context, @Nullable Device device) {
         this.device = device;
         this.context = context;
+
+        if (device != null) {
+            this.preferences = this.context.getSharedPreferences(this.getSharedPreferencesName(), Context.MODE_PRIVATE);
+        }
+    }
+
+    public String getSharedPreferencesName() {
+        if (device == null) {
+            throw new RuntimeException("You have to call setContext() before you can call getSharedPreferencesName()");
+        }
+
+        if (this.supportsDeviceSpecificSettings())
+            return this.device.getDeviceId() + "_" + this.getPluginKey() + "_preferences";
+        else
+            return this.getPluginKey() + "_preferences";
+    }
+
+    @Nullable
+    public SharedPreferences getPreferences() {
+        return this.preferences;
     }
 
     /**
@@ -121,6 +146,30 @@ public abstract class Plugin {
         return false;
     }
 
+    /**
+     * Called to find out if a plugin supports device specific settings.
+     * If you return true your PluginSettingsFragment will use the device
+     * specific SharedPreferences to store the settings.
+     *
+     * @return true if this plugin supports device specific settings
+     */
+    public boolean supportsDeviceSpecificSettings() { return false; }
+
+    /**
+     * Called when it's time to move the plugin settings from the global preferences
+     * to device specific preferences
+     *
+     * @param globalSharedPreferences The global Preferences to copy the settings from
+     */
+    public void copyGlobalToDeviceSpecificSettings(SharedPreferences globalSharedPreferences) {}
+
+    /**
+     *  Called when the plugin should remove it's settings from the provided ShardPreferences
+     *
+     * @param sharedPreferences The SharedPreferences to remove the settings from
+     */
+    public void removeSettings(SharedPreferences sharedPreferences) {}
+
     /**
      * If hasSettings returns true, this will be called when the user
      * wants to access this plugin's preferences. The default implementation
@@ -244,5 +293,4 @@ public abstract class Plugin {
     public int getMinSdk() {
         return Build.VERSION_CODES.BASE;
     }
-
 }

src/org/kde/kdeconnect/Plugins/PluginFactory.java

@@ -42,14 +42,15 @@ public class PluginFactory {
     public static class PluginInfo {
 
         PluginInfo(String displayName, String description, Drawable icon,
-                   boolean enabledByDefault, boolean hasSettings, boolean listenToUnpaired,
+                   boolean enabledByDefault, boolean hasSettings, boolean supportsDeviceSpecificSettings,
-                   String[] supportedPacketTypes, String[] outgoingPacketTypes,
+                   boolean listenToUnpaired, String[] supportedPacketTypes, String[] outgoingPacketTypes,
                    Class<? extends Plugin> instantiableClass) {
             this.displayName = displayName;
             this.description = description;
             this.icon = icon;
             this.enabledByDefault = enabledByDefault;
             this.hasSettings = hasSettings;
+            this.supportsDeviceSpecificSettings = supportsDeviceSpecificSettings;
             this.listenToUnpaired = listenToUnpaired;
             HashSet<String> incoming = new HashSet<>();
             if (supportedPacketTypes != null) Collections.addAll(incoming, supportedPacketTypes);
@@ -76,6 +77,8 @@ public class PluginFactory {
             return hasSettings;
         }
 
+        public boolean supportsDeviceSpecificSettings() { return supportsDeviceSpecificSettings; }
+
         public boolean isEnabledByDefault() {
             return enabledByDefault;
         }
@@ -101,6 +104,7 @@ public class PluginFactory {
         private final Drawable icon;
         private final boolean enabledByDefault;
         private final boolean hasSettings;
+        private final boolean supportsDeviceSpecificSettings;
         private final boolean listenToUnpaired;
         private final Set<String> supportedPacketTypes;
         private final Set<String> outgoingPacketTypes;
@@ -120,8 +124,9 @@ public class PluginFactory {
                 Plugin p = ((Plugin) pluginClass.newInstance());
                 p.setContext(context, null);
                 PluginInfo info = new PluginInfo(p.getDisplayName(), p.getDescription(), p.getIcon(),
-                        p.isEnabledByDefault(), p.hasSettings(), p.listensToUnpairedDevices(),
+                        p.isEnabledByDefault(), p.hasSettings(), p.supportsDeviceSpecificSettings(),
-                        p.getSupportedPacketTypes(), p.getOutgoingPacketTypes(), p.getClass());
+                        p.listensToUnpairedDevices(), p.getSupportedPacketTypes(),
+                        p.getOutgoingPacketTypes(), p.getClass());
                 pluginInfo.put(p.getPluginKey(), info);
             }
         } catch (Exception e) {

src/org/kde/kdeconnect/Plugins/SftpPlugin/SftpPlugin.java

@@ -27,6 +27,8 @@ import android.net.Uri;
 import android.os.Build;
 import android.util.Log;
 
+import androidx.annotation.NonNull;
+
 import org.json.JSONException;
 import org.json.JSONObject;
 import org.kde.kdeconnect.NetworkPacket;
@@ -43,19 +45,16 @@ import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
 
-import androidx.annotation.NonNull;
-import androidx.preference.PreferenceManager;
-
 @PluginFactory.LoadablePlugin
 public class SftpPlugin extends Plugin implements SharedPreferences.OnSharedPreferenceChangeListener {
 
     private final static String PACKET_TYPE_SFTP = "kdeconnect.sftp";
     private final static String PACKET_TYPE_SFTP_REQUEST = "kdeconnect.sftp.request";
 
-    private static final SimpleSftpServer server = new SimpleSftpServer();
+    static int PREFERENCE_KEY_STORAGE_INFO_LIST = R.string.sftp_preference_key_storage_info_list;
+    private static int PREFERENCE_KEY_ADD_CAMERA_SHORTCUT = R.string.sftp_preference_key_add_camera_shortcut;
 
-    private String KeyStorageInfoList;
+    private static final SimpleSftpServer server = new SimpleSftpServer();
-    private String KeyAddCameraShortcut;
 
     @Override
     public String getDisplayName() {
@@ -69,14 +68,11 @@ public class SftpPlugin extends Plugin implements SharedPreferences.OnSharedPref
 
     @Override
     public boolean onCreate() {
-        KeyStorageInfoList = context.getString(R.string.sftp_preference_key_storage_info_list);
-        KeyAddCameraShortcut = context.getString(R.string.sftp_preference_key_add_camera_shortcut);
-
         try {
             server.init(context, device);
 
             if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.KITKAT) {
-                return SftpSettingsFragment.getStorageInfoList(context).size() != 0;
+                return SftpSettingsFragment.getStorageInfoList(context, this).size() != 0;
             }
 
             return true;
@@ -89,7 +85,7 @@ public class SftpPlugin extends Plugin implements SharedPreferences.OnSharedPref
     @Override
     public boolean checkOptionalPermissions() {
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
-            return SftpSettingsFragment.getStorageInfoList(context).size() != 0;
+            return SftpSettingsFragment.getStorageInfoList(context, this).size() != 0;
         }
 
         return true;
@@ -110,7 +106,9 @@ public class SftpPlugin extends Plugin implements SharedPreferences.OnSharedPref
     @Override
     public void onDestroy() {
         server.stop();
-        PreferenceManager.getDefaultSharedPreferences(context).unregisterOnSharedPreferenceChangeListener(this);
+        if (preferences != null) {
+            preferences.unregisterOnSharedPreferenceChangeListener(this);
+        }
     }
 
     @Override
@@ -119,7 +117,7 @@ public class SftpPlugin extends Plugin implements SharedPreferences.OnSharedPref
             ArrayList<String> paths = new ArrayList<>();
             ArrayList<String> pathNames = new ArrayList<>();
 
-            List<StorageInfo> storageInfoList = SftpSettingsFragment.getStorageInfoList(context);
+            List<StorageInfo> storageInfoList = SftpSettingsFragment.getStorageInfoList(context, this);
             Collections.sort(storageInfoList, new StorageInfo.UriNameComparator());
 
             if (storageInfoList.size() > 0) {
@@ -141,7 +139,9 @@ public class SftpPlugin extends Plugin implements SharedPreferences.OnSharedPref
             removeChildren(storageInfoList);
 
             if (server.start(storageInfoList)) {
-                PreferenceManager.getDefaultSharedPreferences(context).registerOnSharedPreferenceChangeListener(this);
+                if (preferences != null) {
+                    preferences.registerOnSharedPreferenceChangeListener(this);
+                }
 
                 NetworkPacket np2 = new NetworkPacket(PACKET_TYPE_SFTP);
 
@@ -170,11 +170,13 @@ public class SftpPlugin extends Plugin implements SharedPreferences.OnSharedPref
     private void getPathsAndNamesForStorageInfoList(List<String> paths, List<String> pathNames, List<StorageInfo> storageInfoList) {
         StorageInfo prevInfo = null;
         StringBuilder pathBuilder = new StringBuilder();
-        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
+
         boolean addCameraShortcuts = false;
 
         if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.KITKAT) {
-            addCameraShortcuts = prefs.getBoolean(context.getString(R.string.sftp_preference_key_add_camera_shortcut), true);
+            if (preferences != null) {
+                addCameraShortcuts = preferences.getBoolean(context.getString(PREFERENCE_KEY_ADD_CAMERA_SHORTCUT), true);
+            }
         }
 
         for (StorageInfo curInfo : storageInfoList) {
@@ -245,6 +247,33 @@ public class SftpPlugin extends Plugin implements SharedPreferences.OnSharedPref
         return true;
     }
 
+    @Override
+    public boolean supportsDeviceSpecificSettings() { return true; }
+
+    @Override
+    public void copyGlobalToDeviceSpecificSettings(SharedPreferences globalSharedPreferences) {
+        String KeyStorageInfoList = context.getString(PREFERENCE_KEY_STORAGE_INFO_LIST);
+        String KeyAddCameraShortcut = context.getString(PREFERENCE_KEY_ADD_CAMERA_SHORTCUT);
+
+        if (this.preferences != null &&
+                (!this.preferences.contains(KeyStorageInfoList) || !this.preferences.contains(KeyAddCameraShortcut))) {
+            this.preferences
+                    .edit()
+                    .putString(KeyStorageInfoList, globalSharedPreferences.getString(KeyStorageInfoList, "[]"))
+                    .putBoolean(KeyAddCameraShortcut, globalSharedPreferences.getBoolean(KeyAddCameraShortcut, true))
+                    .apply();
+        }
+    }
+
+    @Override
+    public void removeSettings(SharedPreferences sharedPreferences) {
+        sharedPreferences
+                .edit()
+                .remove(context.getString(PREFERENCE_KEY_STORAGE_INFO_LIST))
+                .remove(context.getString(PREFERENCE_KEY_ADD_CAMERA_SHORTCUT))
+                .apply();
+    }
+
     @Override
     public PluginSettingsFragment getSettingsFragment(Activity activity) {
         return SftpSettingsFragment.newInstance(getPluginKey());
@@ -252,7 +281,8 @@ public class SftpPlugin extends Plugin implements SharedPreferences.OnSharedPref
 
     @Override
     public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
-        if (key.equals(KeyStorageInfoList) || key.equals(KeyAddCameraShortcut)) {
+        if (key.equals(context.getString(PREFERENCE_KEY_STORAGE_INFO_LIST)) ||
+                key.equals(context.getString(PREFERENCE_KEY_ADD_CAMERA_SHORTCUT))) {
             //TODO: There used to be a way to request an un-mount (see desktop SftpPlugin's Mounter::onPackageReceived) but that is not handled anymore by the SftpPlugin on KDE.
             if (server.isStarted()) {
                 server.stop();

src/org/kde/kdeconnect/Plugins/SftpPlugin/SftpSettingsFragment.java

@@ -36,12 +36,21 @@ import android.view.Menu;
 import android.view.MenuInflater;
 import android.view.MenuItem;
 
+import androidx.annotation.NonNull;
+import androidx.appcompat.view.ActionMode;
+import androidx.fragment.app.Fragment;
+import androidx.preference.Preference;
+import androidx.preference.PreferenceCategory;
+import androidx.preference.PreferenceScreen;
+import androidx.recyclerview.widget.RecyclerView;
+
 import org.json.JSONArray;
 import org.json.JSONException;
 import org.json.JSONObject;
 import org.kde.kdeconnect.BackgroundService;
 import org.kde.kdeconnect.Device;
 import org.kde.kdeconnect.Helpers.StorageHelper;
+import org.kde.kdeconnect.Plugins.Plugin;
 import org.kde.kdeconnect.UserInterface.PluginSettingsActivity;
 import org.kde.kdeconnect.UserInterface.PluginSettingsFragment;
 import org.kde.kdeconnect_tp.R;
@@ -52,15 +61,6 @@ import java.util.Collections;
 import java.util.List;
 import java.util.ListIterator;
 
-import androidx.annotation.NonNull;
-import androidx.appcompat.view.ActionMode;
-import androidx.fragment.app.Fragment;
-import androidx.preference.Preference;
-import androidx.preference.PreferenceCategory;
-import androidx.preference.PreferenceManager;
-import androidx.preference.PreferenceScreen;
-import androidx.recyclerview.widget.RecyclerView;
-
 //TODO: Is it possible on API 19 to select a directory and then have write permission for everything beneath it
 //TODO: Is it necessary to check if uri permissions are still in place? If it is make the user aware of the fact (red text or something)
 public class SftpSettingsFragment
@@ -116,10 +116,10 @@ public class SftpSettingsFragment
 
         int sdkInt = Build.VERSION.SDK_INT;
 
-        storageInfoList = getStorageInfoList(requireContext());
+        storageInfoList = getStorageInfoList(requireContext(), plugin);
 
         PreferenceScreen preferenceScreen = getPreferenceScreen();
-        preferenceCategory = (PreferenceCategory) preferenceScreen
+        preferenceCategory = preferenceScreen
                 .findPreference(getString(R.string.sftp_preference_key_preference_category));
 
         if (sdkInt <= 19) {
@@ -245,30 +245,30 @@ public class SftpSettingsFragment
     }
 
     private void saveStorageInfoList() {
-        SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(requireContext());
+        SharedPreferences preferences = this.plugin.getPreferences();
 
         JSONArray jsonArray = new JSONArray();
 
         try {
-            for (SftpPlugin.StorageInfo storageInfo : storageInfoList) {
+            for (SftpPlugin.StorageInfo storageInfo : this.storageInfoList) {
                 jsonArray.put(storageInfo.toJSON());
             }
         } catch (JSONException ignored) {}
 
         preferences
                 .edit()
-                .putString(requireContext().getString(R.string.sftp_preference_key_storage_info_list), jsonArray.toString())
+                .putString(requireContext().getString(SftpPlugin.PREFERENCE_KEY_STORAGE_INFO_LIST), jsonArray.toString())
                 .apply();
     }
 
     @NonNull
-    static List<SftpPlugin.StorageInfo> getStorageInfoList(@NonNull Context context) {
+    static List<SftpPlugin.StorageInfo> getStorageInfoList(@NonNull Context context, @NonNull Plugin plugin) {
         ArrayList<SftpPlugin.StorageInfo> storageInfoList = new ArrayList<>();
 
-        SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
+        SharedPreferences deviceSettings = plugin.getPreferences();
 
-        String jsonString = preferences
+        String jsonString = deviceSettings
-                .getString(context.getString(R.string.sftp_preference_key_storage_info_list), "[]");
+                .getString(context.getString(SftpPlugin.PREFERENCE_KEY_STORAGE_INFO_LIST), "[]");
 
         try {
             JSONArray jsonArray = new JSONArray(jsonString);
@@ -414,11 +414,19 @@ public class SftpSettingsFragment
 
         addStoragePreferences(preferenceCategory);
 
-        Device device = BackgroundService.getInstance().getDevice(getDeviceId());
+        Device device = getDeviceOrThrow();
 
-        if (device != null) {
         device.reloadPluginsFromSettings();
     }
+
+    private Device getDeviceOrThrow() {
+        Device device = BackgroundService.getInstance().getDevice(getDeviceId());
+
+        if (device == null) {
+            throw new RuntimeException("SftpSettingsFragment.getDeviceOrThrow(): No device with id: " + getDeviceId());
+        }
+
+        return device;
     }
 
     @Override

src/org/kde/kdeconnect/UserInterface/PluginSettingsFragment.java

@@ -20,20 +20,27 @@
 
 package org.kde.kdeconnect.UserInterface;
 
+import android.content.Context;
 import android.os.Bundle;
 
+import androidx.annotation.NonNull;
+import androidx.preference.PreferenceFragmentCompat;
+import androidx.preference.PreferenceManager;
+
+import org.kde.kdeconnect.BackgroundService;
+import org.kde.kdeconnect.Device;
+import org.kde.kdeconnect.Plugins.Plugin;
 import org.kde.kdeconnect.Plugins.PluginFactory;
 import org.kde.kdeconnect_tp.R;
 
 import java.util.Locale;
 
-import androidx.annotation.NonNull;
-import androidx.preference.PreferenceFragmentCompat;
-
 public class PluginSettingsFragment extends PreferenceFragmentCompat {
     private static final String ARG_PLUGIN_KEY = "plugin_key";
 
     private String pluginKey;
+    protected Device device;
+    protected Plugin plugin;
 
     public static PluginSettingsFragment newInstance(@NonNull String pluginKey) {
         PluginSettingsFragment fragment = new PluginSettingsFragment();
@@ -60,12 +67,20 @@ public class PluginSettingsFragment extends PreferenceFragmentCompat {
         }
 
         pluginKey = getArguments().getString(ARG_PLUGIN_KEY);
+        this.device = getDeviceOrThrow(getDeviceId());
+        this.plugin = device.getPlugin(pluginKey);
 
         super.onCreate(savedInstanceState);
     }
 
     @Override
     public void onCreatePreferences(Bundle savedInstanceState, String rootKey) {
+        if (this.plugin != null && this.plugin.supportsDeviceSpecificSettings()) {
+            PreferenceManager prefsManager = getPreferenceManager();
+            prefsManager.setSharedPreferencesName(this.plugin.getSharedPreferencesName());
+            prefsManager.setSharedPreferencesMode(Context.MODE_PRIVATE);
+        }
+
         int resFile = getResources().getIdentifier(pluginKey.toLowerCase(Locale.ENGLISH) + "_preferences", "xml",
                 requireContext().getPackageName());
         addPreferencesFromResource(resFile);
@@ -82,4 +97,14 @@ public class PluginSettingsFragment extends PreferenceFragmentCompat {
     public String getDeviceId() {
         return ((PluginSettingsActivity)requireActivity()).getDeviceId();
     }
+
+    private Device getDeviceOrThrow(String deviceId) {
+        Device device = BackgroundService.getInstance().getDevice(deviceId);
+
+        if (device == null) {
+            throw new RuntimeException("PluginSettingsFragment.onCreatePreferences() - No device with id " + getDeviceId());
+        }
+
+        return device;
+    }
 }

src/org/kde/kdeconnect/UserInterface/SettingsFragment.java

@@ -8,14 +8,6 @@ import android.os.Build;
 import android.os.Bundle;
 import android.preference.PreferenceManager;
 import android.text.TextUtils;
-import android.view.View;
-
-import com.google.android.material.snackbar.Snackbar;
-
-import org.kde.kdeconnect.BackgroundService;
-import org.kde.kdeconnect.Helpers.DeviceHelper;
-import org.kde.kdeconnect.Helpers.NotificationHelper;
-import org.kde.kdeconnect_tp.R;
 
 import androidx.preference.EditTextPreference;
 import androidx.preference.Preference;
@@ -24,6 +16,13 @@ import androidx.preference.PreferenceScreen;
 import androidx.preference.SwitchPreferenceCompat;
 import androidx.preference.TwoStatePreference;
 
+import com.google.android.material.snackbar.Snackbar;
+
+import org.kde.kdeconnect.BackgroundService;
+import org.kde.kdeconnect.Helpers.DeviceHelper;
+import org.kde.kdeconnect.Helpers.NotificationHelper;
+import org.kde.kdeconnect_tp.R;
+
 public class SettingsFragment extends PreferenceFragmentCompat {
 
     private MainActivity mainActivity;