Device create/edit dialog: Check address input, fix losing changes on screen rotation (#270)

* Add comments

* Add model/Device#checkDeviceAddresses

* Add checkDeviceAddresses to device create dialog

* FolderActivity: Consolidate createDiscardDialog into showDiscardDialog

* folder_settings: R.id.create => R.id.save

* device_settings: R.id.create => R.id.save

* Edit device dialog: Offer back+discard and save action

* Add deviceNeedsToUpdate to savedInstanceState (fixes #271)

Remove dependency SyncthingService.OnServiceStateChangeListener

* Fix folder settings validation doesn't take place when editing folder (fixes #273) (fixes #265)

* Conditional label of the create/save button

* Remove workaround for rotation: mVersioning

* Fix folder.type is reset from SendOnly to Send&Receive on recreation of FolderActivity while creating a new folder (fixes #274)

* Fix typo

* Fix typo

* Fix typo

* Review - Relocate code

* Move null checks to the beginning of onSave

* Updated de translation

* Add ListenAddressesChanged to EventProcessor

as unhandled event.

app/src/main/java/com/nutomic/syncthingandroid/activities/DeviceActivity.java

@@ -53,9 +53,7 @@ import static com.nutomic.syncthingandroid.util.Compression.METADATA;
 /**
  * Shows device details and allows changing them.
  */
-public class DeviceActivity extends SyncthingActivity
+public class DeviceActivity extends SyncthingActivity {
-        implements
-            SyncthingService.OnServiceStateChangeListener {
 
     public static final String EXTRA_NOTIFICATION_ID =
             "com.github.catfriend1.syncthingandroid.activities.DeviceActivity.NOTIFICATION_ID";
@@ -207,19 +205,47 @@ public class DeviceActivity extends SyncthingActivity
         mCompressionContainer.setOnClickListener(view -> onCompressionContainerClick());
         mCustomSyncConditionsDialog.setOnClickListener(view -> onCustomSyncConditionsDialogClick());
 
-        if (savedInstanceState != null){
-            if (mDevice == null) {
-                mDevice = new Gson().fromJson(savedInstanceState.getString("device"), Device.class);
-            }
-            restoreDialogStates(savedInstanceState);
-        }
-
         findViewById(R.id.editDeviceIdContainer).setVisibility(mIsCreateMode ? View.VISIBLE : View.GONE);
         mShowDeviceIdContainer.setVisibility(!mIsCreateMode ? View.VISIBLE : View.GONE);
-        if (mIsCreateMode) {
+
-            if (mDevice == null) {
+        if (savedInstanceState != null) {
+            Log.d(TAG, "Retrieving state from savedInstanceState ...");
+            mDevice = new Gson().fromJson(savedInstanceState.getString("device"), Device.class);
+            mDeviceNeedsToUpdate = savedInstanceState.getBoolean("deviceNeedsToUpdate");
+            restoreDialogStates(savedInstanceState);
+        } else {
+            // Fresh init of the edit or create mode.
+            if (mIsCreateMode) {
+                Log.d(TAG, "Initializing create mode ...");
                 initDevice();
+                mDeviceNeedsToUpdate = true;
+            } else {
+                // Edit mode.
+                String passedId = getIntent().getStringExtra(EXTRA_DEVICE_ID);
+                Log.d(TAG, "Initializing edit mode: deviceID=" + passedId);
+                RestApi restApi = getApi();
+                List<Device> devices = mConfig.getDevices(restApi, false);
+                mDevice = null;
+                for (Device currentDevice : devices) {
+                    if (currentDevice.deviceID.equals(passedId)) {
+                        mDevice = currentDevice;
+                        break;
+                    }
+                }
+                if (mDevice == null) {
+                    Log.w(TAG, "Device not found in API update, maybe it was deleted?");
+                    finish();
+                    return;
+                }
+                if (restApi != null) {
+                    restApi.getConnections(this::onReceiveConnections);
+                }
+                mDeviceNeedsToUpdate = false;
             }
+        }
+        updateViewsAndSetListeners();
+
+        if (mIsCreateMode) {
             mEditDeviceId.requestFocus();
         } else {
             getWindow().setSoftInputMode(SOFT_INPUT_STATE_ALWAYS_HIDDEN);
@@ -236,10 +262,8 @@ public class DeviceActivity extends SyncthingActivity
             showDeleteDialog();
         }
 
-        if (mIsCreateMode){
+        if (savedInstanceState.getBoolean(IS_SHOWING_DISCARD_DIALOG)){
-            if (savedInstanceState.getBoolean(IS_SHOWING_DISCARD_DIALOG)){
+            showDiscardDialog();
-                showDiscardDialog();
-            }
         }
     }
 
@@ -252,37 +276,11 @@ public class DeviceActivity extends SyncthingActivity
         SyncthingServiceBinder syncthingServiceBinder = (SyncthingServiceBinder) iBinder;
         SyncthingService syncthingService = (SyncthingService) syncthingServiceBinder.getService();
         syncthingService.getNotificationHandler().cancelConsentNotification(getIntent().getIntExtra(EXTRA_NOTIFICATION_ID, 0));
-        syncthingService.registerOnServiceStateChangeListener(DeviceActivity.this);
-    }
-
-    @Override
-    public void onServiceStateChange(SyncthingService.State currentState) {
-        if (!mIsCreateMode) {
-            RestApi restApi = getApi();
-            List<Device> devices = mConfig.getDevices(restApi, false);
-            String passedId = getIntent().getStringExtra(EXTRA_DEVICE_ID);
-            mDevice = null;
-            for (Device currentDevice : devices) {
-                if (currentDevice.deviceID.equals(passedId)) {
-                    mDevice = currentDevice;
-                    break;
-                }
-            }
-            if (mDevice == null) {
-                Log.w(TAG, "Device not found in API update, maybe it was deleted?");
-                finish();
-                return;
-            }
-            if (restApi != null) {
-                restApi.getConnections(this::onReceiveConnections);
-            }
-        }
-        updateViewsAndSetListeners();
     }
 
     @Override
     public void onBackPressed() {
-        if (mIsCreateMode) {
+        if (mDeviceNeedsToUpdate) {
             showDiscardDialog();
         }
         else {
@@ -290,24 +288,12 @@ public class DeviceActivity extends SyncthingActivity
         }
     }
 
-    @Override
-    public void onPause() {
-        super.onPause();
-
-        // We don't want to update every time a TextView's character changes,
-        // so we hold off until the view stops being visible to the user.
-        if (mDeviceNeedsToUpdate) {
-            updateDevice();
-        }
-    }
-
     @Override
     public void onDestroy() {
         super.onDestroy();
         SyncthingService syncthingService = getService();
         if (syncthingService != null) {
             syncthingService.getNotificationHandler().cancelConsentNotification(getIntent().getIntExtra(EXTRA_NOTIFICATION_ID, 0));
-            syncthingService.unregisterOnServiceStateChangeListener(DeviceActivity.this);
         }
         mEditDeviceId.removeTextChangedListener(mIdTextWatcher);
         mNameView.removeTextChangedListener(mNameTextWatcher);
@@ -321,10 +307,10 @@ public class DeviceActivity extends SyncthingActivity
     public void onSaveInstanceState(Bundle outState) {
         super.onSaveInstanceState(outState);
         outState.putString("device", new Gson().toJson(mDevice));
-        if (mIsCreateMode){
+        outState.putBoolean("deviceNeedsToUpdate", mDeviceNeedsToUpdate);
-            outState.putBoolean(IS_SHOWING_DISCARD_DIALOG, mDiscardDialog != null && mDiscardDialog.isShowing());
+
-            Util.dismissDialogSafe(mDiscardDialog, this);
+        outState.putBoolean(IS_SHOWING_DISCARD_DIALOG, mDiscardDialog != null && mDiscardDialog.isShowing());
-        }
+        Util.dismissDialogSafe(mDiscardDialog, this);
 
         outState.putBoolean(IS_SHOWING_COMPRESSION_DIALOG, mCompressionDialog != null && mCompressionDialog.isShowing());
         Util.dismissDialogSafe(mCompressionDialog, this);
@@ -405,7 +391,7 @@ public class DeviceActivity extends SyncthingActivity
 
     @Override
     public boolean onPrepareOptionsMenu(Menu menu) {
-        menu.findItem(R.id.create).setVisible(mIsCreateMode);
+        menu.findItem(R.id.save).setTitle(mIsCreateMode ? R.string.create : R.string.save_title);
         menu.findItem(R.id.share_device_id).setVisible(!mIsCreateMode);
         menu.findItem(R.id.remove).setVisible(!mIsCreateMode);
         return true;
@@ -414,24 +400,8 @@ public class DeviceActivity extends SyncthingActivity
     @Override
     public boolean onOptionsItemSelected(MenuItem item) {
         switch (item.getItemId()) {
-            case R.id.create:
+            case R.id.save:
-                if (isEmpty(mDevice.deviceID)) {
+                onSave();
-                    Toast.makeText(this, R.string.device_id_required, Toast.LENGTH_LONG)
-                            .show();
-                    return true;
-                }
-                if (!mDevice.checkDeviceID()) {
-                    Toast.makeText(this, R.string.device_id_invalid, Toast.LENGTH_LONG)
-                            .show();
-                    return true;
-                }
-                if (isEmpty(mDevice.name)) {
-                    Toast.makeText(this, R.string.device_name_required, Toast.LENGTH_LONG)
-                            .show();
-                    return true;
-                }
-                mConfig.addDevice(getApi(), mDevice);
-                finish();
                 return true;
             case R.id.share_device_id:
                 shareDeviceId(this, mDevice.deviceID);
@@ -491,23 +461,51 @@ public class DeviceActivity extends SyncthingActivity
         mDevice.introducedBy = "";
     }
 
-    /**
+    private void onSave() {
-     * Sends the updated device info if in edit mode.
+        if (mDevice == null) {
-     * Preconditions: mDeviceNeedsToUpdate == true
+            Log.e(TAG, "onSave: mDevice == null");
-     */
-    private void updateDevice() {
-        if (mIsCreateMode) {
-            // If we are about to create this device, we cannot update via restApi.
             return;
         }
-        if (mDevice == null) {
+
-            Log.e(TAG, "updateDevice: mDevice == null");
+        // Validate fields.
+        if (isEmpty(mDevice.deviceID)) {
+            Toast.makeText(this, R.string.device_id_required, Toast.LENGTH_LONG)
+                    .show();
+            return;
+        }
+        if (!mDevice.checkDeviceID()) {
+            Toast.makeText(this, R.string.device_id_invalid, Toast.LENGTH_LONG)
+                    .show();
+            return;
+        }
+        if (isEmpty(mDevice.name)) {
+            Toast.makeText(this, R.string.device_name_required, Toast.LENGTH_LONG)
+                    .show();
+            return;
+        }
+        if (!mDevice.checkDeviceAddresses()) {
+            Toast.makeText(this, R.string.device_addresses_invalid, Toast.LENGTH_LONG)
+                    .show();
+            return;
+        }
+
+        if (mIsCreateMode) {
+            Log.v(TAG, "onSave: Adding device with ID = \'" + mDevice.deviceID + "\'");
+            mConfig.addDevice(getApi(), mDevice);
+            finish();
+            return;
+        }
+
+        // Edit mode.
+        if (!mDeviceNeedsToUpdate) {
+            // We've got nothing to save.
+            finish();
             return;
         }
         // Log.v(TAG, "deviceID=" + mDevice.deviceID + ", introducedBy=" + mDevice.introducedBy);
 
         // Save device specific preferences.
-        Log.v(TAG, "updateDevice: mDevice.deviceID = \'" + mDevice.deviceID + "\'");
+        Log.v(TAG, "onSave: Updating device with ID = \'" + mDevice.deviceID + "\'");
         SharedPreferences.Editor editor = mPreferences.edit();
         editor.putBoolean(
             Constants.DYN_PREF_OBJECT_CUSTOM_SYNC_CONDITIONS(Constants.PREF_OBJECT_PREFIX_DEVICE + mDevice.deviceID),
@@ -517,8 +515,13 @@ public class DeviceActivity extends SyncthingActivity
 
         // Update device using RestApi or ConfigXml.
         mConfig.updateDevice(getApi(), mDevice);
+        finish();
+        return;
     }
 
+    /**
+     * Converts text line to addresses array.
+     */
     private List<String> persistableAddresses(CharSequence userInput) {
         if (isEmpty(userInput)) {
             return DYNAMIC_ADDRESS;
@@ -543,6 +546,9 @@ public class DeviceActivity extends SyncthingActivity
         return Arrays.asList(input.split(", "));
     }
 
+    /**
+     * Converts addresses array to a text line.
+     */
     private String displayableAddresses() {
         if (mDevice.addresses == null) {
             return "";

app/src/main/java/com/nutomic/syncthingandroid/activities/FolderActivity.java

@@ -61,8 +61,7 @@ import static android.view.ViewGroup.LayoutParams.WRAP_CONTENT;
 /**
  * Shows folder details and allows changing them.
  */
-public class FolderActivity extends SyncthingActivity
+public class FolderActivity extends SyncthingActivity {
-        implements SyncthingService.OnServiceStateChangeListener {
 
     public static final String EXTRA_NOTIFICATION_ID =
             "com.github.catfriend1.syncthingandroid.activities.FolderActivity.NOTIFICATION_ID";
@@ -125,8 +124,6 @@ public class FolderActivity extends SyncthingActivity
     private Dialog mDeleteDialog;
     private Dialog mDiscardDialog;
 
-    private Folder.Versioning mVersioning;
-
     private final TextWatcher mTextWatcher = new TextWatcherAdapter() {
         @Override
         public void afterTextChanged(Editable s) {
@@ -221,34 +218,72 @@ public class FolderActivity extends SyncthingActivity
         findViewById(R.id.pullOrderContainer).setOnClickListener(v -> showPullOrderDialog());
         findViewById(R.id.versioningContainer).setOnClickListener(v -> showVersioningDialog());
 
-        if (mIsCreateMode) {
+        if (savedInstanceState != null) {
-            if (savedInstanceState != null) {
+            Log.d(TAG, "Retrieving state from savedInstanceState ...");
-                mFolder = new Gson().fromJson(savedInstanceState.getString("mFolder"), Folder.class);
+            mFolder = new Gson().fromJson(savedInstanceState.getString("mFolder"), Folder.class);
-                mFolderUri = savedInstanceState.getParcelable("mFolderUri");
+            mFolderNeedsToUpdate = savedInstanceState.getBoolean("mFolderNeedsToUpdate");
-            }
+            mIgnoreListNeedsToUpdate = savedInstanceState.getBoolean("mIgnoreListNeedsToUpdate");
-            if (mFolder == null) {
+            mFolderUri = savedInstanceState.getParcelable("mFolderUri");
+            restoreDialogStates(savedInstanceState);
+        } else {
+            // Fresh init of the edit or create mode.
+            if (mIsCreateMode) {
+                Log.d(TAG, "Initializing create mode ...");
                 initFolder();
+                mFolderNeedsToUpdate = true;
+            } else {
+                // Edit mode.
+                String passedId = getIntent().getStringExtra(EXTRA_FOLDER_ID);
+                Log.d(TAG, "Initializing edit mode: folder.id=" + passedId);
+                RestApi restApi = getApi();
+                List<Folder> folders = mConfig.getFolders(restApi);
+                mFolder = null;
+                for (Folder currentFolder : folders) {
+                    if (currentFolder.id.equals(passedId)) {
+                        mFolder = currentFolder;
+                        break;
+                    }
+                }
+                if (mFolder == null) {
+                    Log.w(TAG, "Folder not found in API update, maybe it was deleted?");
+                    finish();
+                    return;
+                }
+                mConfig.getFolderIgnoreList(restApi, mFolder, this::onReceiveFolderIgnoreList);
+                mFolderNeedsToUpdate = false;
             }
+
+            // If the extra is set, we should automatically share the current folder with the given device.
+            if (getIntent().hasExtra(EXTRA_DEVICE_ID)) {
+                Device device = new Device();
+                device.deviceID = getIntent().getStringExtra(EXTRA_DEVICE_ID);
+                mFolder.addDevice(device);
+                mFolderNeedsToUpdate = true;
+            }
+        }
+
+        if (mIsCreateMode) {
             mEditIgnoreListTitle.setEnabled(false);
             mEditIgnoreListContent.setEnabled(false);
-        }
+        } else {
-        else {
+            // Edit mode.
-            // Prepare edit mode.
             mIdView.setFocusable(false);
             mIdView.setEnabled(false);
             mPathView.setFocusable(false);
             mPathView.setEnabled(false);
         }
+        checkWriteAndUpdateUI();
+        updateViewsAndSetListeners();
 
         // Open keyboard on label view in edit mode.
         mLabelView.requestFocus();
+    }
 
-        if (savedInstanceState != null) {
+    private void restoreDialogStates(Bundle savedInstanceState) {
-            if (savedInstanceState.getBoolean(IS_SHOWING_DELETE_DIALOG)) {
+        if (savedInstanceState.getBoolean(IS_SHOWING_DELETE_DIALOG)) {
-                showDeleteDialog();
+            showDeleteDialog();
-            } else if (savedInstanceState.getBoolean(IS_SHOW_DISCARD_DIALOG)) {
+        } else if (savedInstanceState.getBoolean(IS_SHOW_DISCARD_DIALOG)) {
-                showDiscardDialog();
+            showDiscardDialog();
-            }
         }
     }
 
@@ -345,7 +380,7 @@ public class FolderActivity extends SyncthingActivity
 
     @Override
     public void onBackPressed() {
-        if (mIsCreateMode) {
+        if (mFolderNeedsToUpdate) {
             showDiscardDialog();
         }
         else {
@@ -353,25 +388,12 @@ public class FolderActivity extends SyncthingActivity
         }
     }
 
-    @Override
-    public void onPause() {
-        super.onPause();
-
-        // We don't want to update every time a TextView's character changes,
-        // so we hold off until the view stops being visible to the user.
-        if (mFolderNeedsToUpdate) {
-            Log.v(TAG, "onPause: mFolderNeedsToUpdate=true, mIgnoreListNeedsToUpdate=" + Boolean.toString(mIgnoreListNeedsToUpdate));
-            updateFolder();
-        }
-    }
-
     @Override
     public void onDestroy() {
         super.onDestroy();
         SyncthingService syncthingService = getService();
         if (syncthingService != null) {
             syncthingService.getNotificationHandler().cancelConsentNotification(getIntent().getIntExtra(EXTRA_NOTIFICATION_ID, 0));
-            syncthingService.unregisterOnServiceStateChangeListener(FolderActivity.this);
         }
         mLabelView.removeTextChangedListener(mTextWatcher);
         mIdView.removeTextChangedListener(mTextWatcher);
@@ -381,17 +403,16 @@ public class FolderActivity extends SyncthingActivity
     @Override
     protected void onSaveInstanceState(Bundle outState) {
         super.onSaveInstanceState(outState);
+        outState.putString("mFolder", new Gson().toJson(mFolder));
+        outState.putBoolean("mFolderNeedsToUpdate", mFolderNeedsToUpdate);
+        outState.putBoolean("mIgnoreListNeedsToUpdate", mIgnoreListNeedsToUpdate);
+        outState.putParcelable("mFolderUri", mFolderUri);
 
         outState.putBoolean(IS_SHOWING_DELETE_DIALOG, mDeleteDialog != null && mDeleteDialog.isShowing());
         Util.dismissDialogSafe(mDeleteDialog, this);
 
         outState.putBoolean(IS_SHOW_DISCARD_DIALOG, mDiscardDialog != null && mDiscardDialog.isShowing());
         Util.dismissDialogSafe(mDiscardDialog, this);
-
-        if (mIsCreateMode) {
-            outState.putString("mFolder", new Gson().toJson(mFolder));
-            outState.putParcelable("mFolderUri", mFolderUri);
-        }
     }
 
     /**
@@ -403,47 +424,6 @@ public class FolderActivity extends SyncthingActivity
         SyncthingServiceBinder syncthingServiceBinder = (SyncthingServiceBinder) iBinder;
         SyncthingService syncthingService = (SyncthingService) syncthingServiceBinder.getService();
         syncthingService.getNotificationHandler().cancelConsentNotification(getIntent().getIntExtra(EXTRA_NOTIFICATION_ID, 0));
-        syncthingService.registerOnServiceStateChangeListener(FolderActivity.this);
-    }
-
-    @Override
-    public void onServiceStateChange(SyncthingService.State currentState) {
-        if (mFolderNeedsToUpdate) {
-            Log.d(TAG, "onServiceStateChange: Suppressing reload of folder config as changes were made to that folder in the meantime.");
-            return;
-        }
-
-        if (!mIsCreateMode) {
-            Log.d(TAG, "onServiceStateChange: (Re)loading folder config ...");
-            RestApi restApi = getApi();
-            List<Folder> folders = mConfig.getFolders(restApi);
-            String passedId = getIntent().getStringExtra(EXTRA_FOLDER_ID);
-            mFolder = null;
-            for (Folder currentFolder : folders) {
-                if (currentFolder.id.equals(passedId)) {
-                    mFolder = currentFolder;
-                    break;
-                }
-            }
-            if (mFolder == null) {
-                Log.w(TAG, "Folder not found in API update, maybe it was deleted?");
-                finish();
-                return;
-            }
-            mConfig.getFolderIgnoreList(restApi, mFolder, this::onReceiveFolderIgnoreList);
-        }
-
-        // If the extra is set, we should automatically share the current folder with the given device.
-        if (getIntent().hasExtra(EXTRA_DEVICE_ID)) {
-            Device device = new Device();
-            device.deviceID = getIntent().getStringExtra(EXTRA_DEVICE_ID);
-            mFolder.addDevice(device);
-            mFolderNeedsToUpdate = true;
-        }
-
-        checkWriteAndUpdateUI();
-        attemptToApplyVersioningConfig();
-        updateViewsAndSetListeners();
     }
 
     private void onReceiveFolderIgnoreList(FolderIgnoreList folderIgnoreList) {
@@ -456,16 +436,6 @@ public class FolderActivity extends SyncthingActivity
         mEditIgnoreListContent.addTextChangedListener(mIgnoreListContentTextWatcher);
     }
 
-    // If the FolderActivity gets recreated after the VersioningDialogActivity is closed, then the result from the VersioningDialogActivity will be received before
-    // the mFolder variable has been recreated, so the versioning config will be stored in the mVersioning variable until the mFolder variable has been
-    // recreated in the onServiceStateChange(). This has been observed to happen after the screen orientation has changed while the VersioningDialogActivity was open.
-    private void attemptToApplyVersioningConfig() {
-        if (mFolder != null && mVersioning != null){
-            mFolder.versioning = mVersioning;
-            mVersioning = null;
-        }
-    }
-
     private void updateViewsAndSetListeners() {
         mLabelView.removeTextChangedListener(mTextWatcher);
         mIdView.removeTextChangedListener(mTextWatcher);
@@ -528,7 +498,7 @@ public class FolderActivity extends SyncthingActivity
 
     @Override
     public boolean onPrepareOptionsMenu(Menu menu) {
-        menu.findItem(R.id.create).setVisible(mIsCreateMode);
+        menu.findItem(R.id.save).setTitle(mIsCreateMode ? R.string.create : R.string.save_title);
         menu.findItem(R.id.remove).setVisible(!mIsCreateMode);
         return true;
     }
@@ -536,39 +506,8 @@ public class FolderActivity extends SyncthingActivity
     @Override
     public boolean onOptionsItemSelected(MenuItem item) {
         switch (item.getItemId()) {
-            case R.id.create:
+            case R.id.save:
-                if (TextUtils.isEmpty(mFolder.id)) {
+                onSave();
-                    Toast.makeText(this, R.string.folder_id_required, Toast.LENGTH_LONG)
-                            .show();
-                    return true;
-                }
-                if (TextUtils.isEmpty(mFolder.label)) {
-                    Toast.makeText(this, R.string.folder_label_required, Toast.LENGTH_LONG)
-                            .show();
-                    return true;
-                }
-                if (TextUtils.isEmpty(mFolder.path)) {
-                    Toast.makeText(this, R.string.folder_path_required, Toast.LENGTH_LONG)
-                            .show();
-                    return true;
-                }
-                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP &&
-                    mFolderUri != null &&
-                    mFolder.type.equals(Constants.FOLDER_TYPE_SEND_ONLY)) {
-                    /**
-                     * Normally, syncthing takes care of creating the ".stfolder" marker.
-                     * This fails on newer android versions if the syncthing binary only has
-                     * readonly access on the path and the user tries to configure a
-                     * sendonly folder. To fix this, we'll precreate the marker using java code.
-                     */
-                    DocumentFile dfFolder = DocumentFile.fromTreeUri(this, mFolderUri);
-                    if (dfFolder != null) {
-                        Log.v(TAG, "Creating new directory " + mFolder.path + File.separator + FOLDER_MARKER_NAME);
-                        dfFolder.createDirectory(FOLDER_MARKER_NAME);
-                    }
-                }
-                mConfig.addFolder(getApi(), mFolder);
-                finish();
                 return true;
             case R.id.remove:
                 showDeleteDialog();
@@ -662,8 +601,12 @@ public class FolderActivity extends SyncthingActivity
                  * because the user most probably intentionally chose a special folder like
                  * "[storage]/Android/data/com.nutomic.syncthingandroid/files"
                  * or enabled root mode thus having write access.
+                 * Default from {@link #initFolder} was already set in {@link #onCreate}.
+                 *      mFolder.type = Constants.FOLDER_TYPE_SEND_RECEIVE;
+                 * We won't set it again here as this would cause user selection to be reset on
+                 * screen rotation - as we don't know if we restored the activity or created
+                 * a fresh one.
                  */
-                mFolder.type = Constants.FOLDER_TYPE_SEND_RECEIVE;
                 updateFolderTypeDescription();
             } else {
                 mEditIgnoreListTitle.setEnabled(true);
@@ -694,6 +637,9 @@ public class FolderActivity extends SyncthingActivity
         return sb.toString();
     }
 
+    /**
+     * Init a new folder in mIsCreateMode, used in {@link #onCreate}.
+     */
     private void initFolder() {
         mFolder = new Folder();
         mFolder.id = (getIntent().hasExtra(EXTRA_FOLDER_ID))
@@ -708,7 +654,7 @@ public class FolderActivity extends SyncthingActivity
          */
         mFolder.rescanIntervalS = 3600;
         mFolder.paused = false;
-        mFolder.type = Constants.FOLDER_TYPE_SEND_RECEIVE;
+        mFolder.type = Constants.FOLDER_TYPE_SEND_RECEIVE;      // Default for {@link #checkWriteAndUpdateUI}.
         mFolder.versioning = new Folder.Versioning();
     }
 
@@ -735,24 +681,60 @@ public class FolderActivity extends SyncthingActivity
         deviceView.setOnCheckedChangeListener(mCheckedListener);
     }
 
-    /**
+    private void onSave() {
-     * Sends the updated folder info if in edit mode.
+        if (mFolder == null) {
-     * Preconditions:
+            Log.e(TAG, "onSave: mFolder == null");
-     *  mFolderNeedsToUpdate == true
-     *  mIgnoreListNeedsToUpdate == true (Optional)
-     */
-    private void updateFolder() {
-        if (mIsCreateMode) {
-            // If we are about to create this folder, we cannot update via restApi.
             return;
         }
-        if (mFolder == null) {
+
-            Log.e(TAG, "updateFolder: mFolder == null");
+        // Validate fields.
+        if (TextUtils.isEmpty(mFolder.id)) {
+            Toast.makeText(this, R.string.folder_id_required, Toast.LENGTH_LONG)
+                    .show();
+            return;
+        }
+        if (TextUtils.isEmpty(mFolder.label)) {
+            Toast.makeText(this, R.string.folder_label_required, Toast.LENGTH_LONG)
+                    .show();
+            return;
+        }
+        if (TextUtils.isEmpty(mFolder.path)) {
+            Toast.makeText(this, R.string.folder_path_required, Toast.LENGTH_LONG)
+                    .show();
+            return;
+        }
+
+        if (mIsCreateMode) {
+            Log.v(TAG, "onSave: Adding folder with ID = \'" + mFolder.id + "\'");
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP &&
+                mFolderUri != null &&
+                mFolder.type.equals(Constants.FOLDER_TYPE_SEND_ONLY)) {
+                /**
+                 * Normally, syncthing takes care of creating the ".stfolder" marker.
+                 * This fails on newer android versions if the syncthing binary only has
+                 * readonly access on the path and the user tries to configure a
+                 * sendonly folder. To fix this, we'll precreate the marker using java code.
+                 */
+                DocumentFile dfFolder = DocumentFile.fromTreeUri(this, mFolderUri);
+                if (dfFolder != null) {
+                    Log.v(TAG, "onSave: Creating new directory " + mFolder.path + File.separator + FOLDER_MARKER_NAME);
+                    dfFolder.createDirectory(FOLDER_MARKER_NAME);
+                }
+            }
+            mConfig.addFolder(getApi(), mFolder);
+            finish();
+            return;
+        }
+
+        // Edit mode.
+        if (!mFolderNeedsToUpdate) {
+            // We've got nothing to save.
+            finish();
             return;
         }
 
         // Save folder specific preferences.
-        Log.v(TAG, "updateFolder: mFolder.id = \'" + mFolder.id + "\'");
+        Log.v(TAG, "onSave: Updating folder with ID = \'" + mFolder.id + "\'");
         SharedPreferences.Editor editor = mPreferences.edit();
         editor.putBoolean(
             Constants.DYN_PREF_OBJECT_CUSTOM_SYNC_CONDITIONS(Constants.PREF_OBJECT_PREFIX_FOLDER + mFolder.id),
@@ -770,41 +752,39 @@ public class FolderActivity extends SyncthingActivity
 
         // Update folder using RestApi or ConfigXml.
         mConfig.updateFolder(restApi, mFolder);
+        finish();
+        return;
     }
 
     private void showDiscardDialog(){
-        mDiscardDialog = createDiscardDialog();
+        mDiscardDialog = new AlertDialog.Builder(this)
-        mDiscardDialog.show();
-    }
-
-    private Dialog createDiscardDialog() {
-        return new AlertDialog.Builder(this)
                 .setMessage(R.string.dialog_discard_changes)
                 .setPositiveButton(android.R.string.ok, (dialog, which) -> finish())
                 .setNegativeButton(android.R.string.cancel, null)
                 .create();
+        mDiscardDialog.show();
     }
 
     private void updateVersioning(Bundle arguments) {
-        if (mFolder != null){
+        if (mFolder == null) {
-            mVersioning = mFolder.versioning;
+            Log.e(TAG, "updateVersioning: mFolder == null");
-        } else {
+            return;
-            mVersioning = new Folder.Versioning();
+        }
+        if (mFolder.versioning == null) {
+            mFolder.versioning = new Folder.Versioning();
         }
 
         String type = arguments.getString("type");
         arguments.remove("type");
 
-        if (type.equals("none")){
+        if (type.equals("none")) {
-            mVersioning = new Folder.Versioning();
+            mFolder.versioning = new Folder.Versioning();
         } else {
             for (String key : arguments.keySet()) {
-                mVersioning.params.put(key, arguments.getString(key));
+                mFolder.versioning.params.put(key, arguments.getString(key));
             }
-            mVersioning.type = type;
+            mFolder.versioning.type = type;
         }
-
-        attemptToApplyVersioningConfig();
         updateVersioningDescription();
         mFolderNeedsToUpdate = true;
     }

app/src/main/java/com/nutomic/syncthingandroid/model/Device.java

@@ -24,6 +24,8 @@ public class Device {
     public List<PendingFolder> pendingFolders;
     public List<IgnoredFolder> ignoredFolders;
 
+    // private static final String TAG = "Device";
+
     /**
      * Relevant fields for Folder.List<Device> "shared-with-device" model,
      * handled by {@link ConfigRouter#updateFolder and ConfigXml#updateFolder}
@@ -112,4 +114,93 @@ public class Device {
                 return false;
         }
     }
+
+    /**
+     * Returns if device.addresses elements are correctly formatted.
+     * See https://docs.syncthing.net/users/config.html#device-element for what is correct.
+     * It can be improved in the future because it doesn't catch all mistakes a user can do.
+     * It catches the most common mistakes.
+     */
+    public Boolean checkDeviceAddresses() {
+        if (this.addresses == null) {
+            return false;
+        }
+        for (String address : this.addresses) {
+            // Log.v(TAG, "address=(" + address + ")");
+            if (address.equals("dynamic")) {
+                continue;
+            }
+
+            /**
+             * RegEx documentation:
+             *
+             * - Matching
+             *      tcp://127.0.0.1:4000
+             *      tcp4://127.0.0.1:4000
+             *      tcp6://127.0.0.1:4000
+             *      tcp4://127.0.0.1
+             *      tcp://[2001:db8::23:42]
+             *      tcp://[2001:db8::23:42]:12345
+             *      tcp://myserver
+             *      tcp://myserver:12345
+             *
+             * - Not-Matching
+             *      tcp8://127.0.0.1
+             *      udp4://127.0.0.1
+             */
+            if (!address.matches("^tcp([46])?://.*$")) {
+                // Log.v(TAG, "Invalid protocol.");
+                return false;
+            }
+
+            // Separate protocol from address and port.
+            String[] addressSplit = address.split("://");
+            if (addressSplit.length == 1) {
+                // There's only the protocol given, nothing more.
+                // Log.v(TAG, "There's only the protocol given, nothing more.");
+                return false;
+            }
+            else if (addressSplit.length == 2) {
+                // Check if the address ends with ":" or "]:"
+                if (addressSplit[addressSplit.length-1].endsWith(":") ||
+                        addressSplit[addressSplit.length-1].endsWith("]:")) {
+                    // The address ends with ":". Will match "tcp://myserver:"
+                    // Log.v(TAG, "address ends with \":\" or \"]:\". Will match \"tcp://myserver:\".");
+                    return false;
+                }
+
+                // Check if there's a "hostname:port" number given in the part after "://".
+                String[] hostnamePortSplit = addressSplit[addressSplit.length-1].split(":");
+                if (hostnamePortSplit.length > 1) {
+                    // Check if the hostname or IP address given before the port is empty.
+                    if (TextUtils.isEmpty(hostnamePortSplit[0])) {
+                        // Empty hostname or IP address before the port. Will match "tcp://:4000"
+                        // Log.v(TAG, "Empty hostname or IP address before the port.");
+                        return false;
+                    }
+
+                    // Check if there's a port number given in the last part.
+                    String potentialPort = hostnamePortSplit[hostnamePortSplit.length-1];
+                    if (!potentialPort.endsWith("]")) {
+                        // It's not the end of an IPv6 address and likely a port number.
+                        // Log.v(TAG, "... potentialPort=(" + potentialPort + ")");
+                        Integer port = 0;
+                        try {
+                            port = Integer.parseInt(potentialPort);
+                        } catch (Exception e) {
+                        }
+                        if (port < 1 || port > 65535) {
+                            // Invalid port number.
+                            // Log.v(TAG, "Invalid port number.");
+                            return false;
+                        }
+                    }
+                }
+            } else {
+                // Protocol is given more than one time. Will match "tcp://tcp://"
+                return false;
+            }
+        }
+        return true;
+    }
 }

app/src/main/java/com/nutomic/syncthingandroid/service/EventProcessor.java

@@ -162,6 +162,7 @@ public class EventProcessor implements  Runnable, RestApi.OnReceiveEventListener
             case "FolderSummary":
             case "FolderWatchStateChanged":
             case "ItemStarted":
+            case "ListenAddressesChanged":
             case "LocalIndexUpdated":
             case "LoginAttempt":
             case "RemoteDownloadProgress":

app/src/main/res/menu/device_settings.xml

@@ -4,7 +4,7 @@
     xmlns:app="http://schemas.android.com/apk/res-auto">
 
     <item
-        android:id="@+id/create"
+        android:id="@+id/save"
         android:title="@string/add"
         android:icon="@drawable/ic_done_white_24dp"
         app:showAsAction="always|withText" />

app/src/main/res/menu/folder_settings.xml

@@ -4,7 +4,7 @@
     xmlns:app="http://schemas.android.com/apk/res-auto">
 
     <item
-        android:id="@+id/create"
+        android:id="@+id/save"
         android:icon="@drawable/ic_done_white_24dp"
         android:title="@string/create"
         app:showAsAction="always|withText" />

app/src/main/res/values-de/strings.xml

@@ -305,6 +305,9 @@ Bitte melden Sie auftretende Probleme via GitHub.</string>
     <!-- Toast shown when trying to create a device with an empty name -->
     <string name="device_name_required">Der Gerätename darf nicht leer sein</string>
 
+    <!-- Toast shown when trying to create a device with invalid addresses -->
+    <string name="device_addresses_invalid">Die Geräteadressen sind nicht im richtigen Format. Bitte versuche es erneut. Sieh Dir die Syncthing Doku für weitere Hilfe an.</string>
+
     <!-- Content description for device ID qr code icon -->
     <string name="scan_qr_code_description">QR Code scannen</string>
 

app/src/main/res/values/strings.xml

@@ -308,6 +308,9 @@ Please report any problems you encounter via Github.</string>
     <!-- Toast shown when trying to create a device with an empty name -->
     <string name="device_name_required">The device name must not be empty</string>
 
+    <!-- Toast shown when trying to create a device with invalid addresses -->
+    <string name="device_addresses_invalid">The device addresses are not formatted correctly. Please retry. Look at the Syncthing docs for more info.</string>
+
     <!-- Content description for device ID qr code icon -->
     <string name="scan_qr_code_description">Scan QR Code</string>