fixes #700

main/ui/src/main/java/org/cryptomator/ui/controllers/SettingsController.java

@@ -33,6 +33,7 @@ import org.apache.commons.lang3.SystemUtils;
 import org.cryptomator.common.settings.VolumeImpl;
 import org.cryptomator.common.settings.Settings;
 import org.cryptomator.ui.l10n.Localization;
+import org.cryptomator.ui.model.Volume;
 
 @Singleton
 public class SettingsController implements ViewController {
@@ -93,7 +94,7 @@ public class SettingsController implements ViewController {
 		checkForUpdatesCheckbox.setSelected(settings.checkForUpdates().get() && !areUpdatesManagedExternally());
 
 		//NIOADAPTER
-		volume.getItems().addAll(getSupportedAdapters());
+		volume.getItems().addAll(Volume.getCurrentSupportedAdapters());
 		volume.setValue(settings.preferredVolumeImpl().get());
 		volume.setConverter(new NioAdapterImplStringConverter());
 
@@ -127,11 +128,6 @@ public class SettingsController implements ViewController {
 		settings.debugMode().bind(debugModeCheckbox.selectedProperty());
 	}
 
-	private VolumeImpl[] getSupportedAdapters() {
-		// TODO: filter depending on supported drivers
-		return VolumeImpl.values();
-	}
-
 	@Override
 	public Parent getRoot() {
 		return root;

main/ui/src/main/java/org/cryptomator/ui/model/DokanyVolume.java

@@ -28,7 +28,7 @@ public class DokanyVolume implements Volume {
 
 	@Override
 	public boolean isSupported() {
-		return MountFactory.isApplicable();
+		return this.isSupportedStatic();
 	}
 
 	//TODO: Drive letter 'A' as mount point is invalid in dokany. maybe we should do already here something against it
@@ -42,11 +42,11 @@ public class DokanyVolume implements Volume {
 			//TODO: can we assume the we have at least one free drive letter?
 
 			//this is a temporary fix for 'A' being an invalid drive letter
-			if(!windowsDriveLetters.getAvailableDriveLetters().isEmpty()){
+			if (!windowsDriveLetters.getAvailableDriveLetters().isEmpty()) {
 				Iterator<Character> winDriveLetterIt = windowsDriveLetters.getAvailableDriveLetters().iterator();
-				do{
+				do {
 					driveLetter = winDriveLetterIt.next();
-				}while (winDriveLetterIt.hasNext() && driveLetter == 65);
+				} while (winDriveLetterIt.hasNext() && driveLetter == 65);
 //			if (!windowsDriveLetters.getAvailableDriveLetters().isEmpty()) {
 //				driveLetter = windowsDriveLetters.getAvailableDriveLetters().iterator().next();
 			} else {
@@ -69,4 +69,8 @@ public class DokanyVolume implements Volume {
 	public void unmount() {
 		mount.close();
 	}
+
+	public static boolean isSupportedStatic() {
+		return MountFactory.isApplicable();
+	}
 }

main/ui/src/main/java/org/cryptomator/ui/model/FuseVolume.java

@@ -60,11 +60,10 @@ public class FuseVolume implements Volume {
 	private String createDirIfNotExist(String prefix, String dirName) throws IOException {
 		Path p = Paths.get(prefix, dirName + vaultSettings.getId());
 		if (Files.isDirectory(p)) {
-			try(DirectoryStream<Path> emptyCheck = Files.newDirectoryStream(p)){
-				if(emptyCheck.iterator().hasNext()){
+			try (DirectoryStream<Path> emptyCheck = Files.newDirectoryStream(p)) {
+				if (emptyCheck.iterator().hasNext()) {
 					throw new DirectoryNotEmptyException("Mount point is not empty.");
-				}
-				else {
+				} else {
 					LOG.info("Directory already exists and is empty. Using it as mount point.");
 					return p.toString();
 				}
@@ -119,6 +118,10 @@ public class FuseVolume implements Volume {
 
 	@Override
 	public boolean isSupported() {
+		return this.isSupportedStatic();
+	}
+
+	public static boolean isSupportedStatic() {
 		return (SystemUtils.IS_OS_MAC_OSX || SystemUtils.IS_OS_LINUX) && FuseMountFactory.isFuseSupported();
 	}
 

main/ui/src/main/java/org/cryptomator/ui/model/Volume.java

@@ -1,8 +1,10 @@
 package org.cryptomator.ui.model;
 
+import org.cryptomator.common.settings.VolumeImpl;
 import org.cryptomator.cryptofs.CryptoFileSystem;
 
 import java.io.IOException;
+import java.util.stream.Stream;
 
 /**
  * Takes a Volume and usess it to mount an unlocked vault
@@ -11,12 +13,12 @@ public interface Volume {
 
 	/**
 	 * Checks in constant time whether this volume type is supported on the system running Cryptomator.
+	 *
 	 * @return true if this volume can be mounted
 	 */
 	boolean isSupported();
 
 	/**
-	 *
 	 * @param fs
 	 * @throws IOException
 	 */
@@ -36,6 +38,21 @@ public interface Volume {
 		throw new VolumeException("Operation not supported.");
 	}
 
+	static VolumeImpl[] getCurrentSupportedAdapters() {
+		return Stream.of(VolumeImpl.values()).filter(impl -> {
+			switch (impl) {
+				case WEBDAV:
+					return WebDavVolume.isSupportedStatic();
+				case DOKANY:
+					return DokanyVolume.isSupportedStatic();
+				case FUSE:
+					return FuseVolume.isSupportedStatic();
+				default:
+					return false;//throw new IllegalStateException("Adapter not implemented.");
+			}
+		}).toArray(VolumeImpl[]::new);
+	}
+
 	/**
 	 * Exception thrown when a volume-specific command such as mount/unmount/reveal failed.
 	 */

main/ui/src/main/java/org/cryptomator/ui/model/WebDavVolume.java

@@ -116,11 +116,16 @@ public class WebDavVolume implements Volume {
 
 	@Override
 	public boolean isSupported() {
-		return true;
+		return this.isSupportedStatic();
 	}
 
 	@Override
 	public boolean supportsForcedUnmount() {
 		return mount != null && mount.forced().isPresent();
 	}
+
+
+	public static boolean isSupportedStatic() {
+		return true;
+	}
 }