Merge branch 'master' into 916-settings

# Conflicts:
#	app/src/main/java/it/niedermann/owncloud/notes/persistence/NotesRepository.java
#	app/src/main/java/it/niedermann/owncloud/notes/shared/model/ApiVersion.java
#	app/src/main/res/values/strings.xml

16 files changed, 224 insertions, 153 deletions

diff --git a/app/src/main/java/it/niedermann/owncloud/notes/shared/account/AccountChooserViewHolder.java b/app/src/main/java/it/niedermann/owncloud/notes/shared/account/AccountChooserViewHolder.java
index 7688b1b1..5d3d2963 100644
--- a/app/src/main/java/it/niedermann/owncloud/notes/shared/account/AccountChooserViewHolder.java
+++ b/app/src/main/java/it/niedermann/owncloud/notes/shared/account/AccountChooserViewHolder.java
@@ -31,7 +31,7 @@ public class AccountChooserViewHolder extends RecyclerView.ViewHolder {
                 .into(binding.accountItemAvatar);
 
         binding.accountLayout.setOnClickListener((v) -> targetAccountConsumer.accept(localAccount));
-        binding.accountName.setText(localAccount.getUserName());
+        binding.accountName.setText(localAccount.getDisplayName());
         binding.accountHost.setText(Uri.parse(localAccount.getUrl()).getHost());
     }
 }
\ No newline at end of file
diff --git a/app/src/main/java/it/niedermann/owncloud/notes/shared/model/ApiVersion.java b/app/src/main/java/it/niedermann/owncloud/notes/shared/model/ApiVersion.java
index ee2fdc3a..589f2571 100644
--- a/app/src/main/java/it/niedermann/owncloud/notes/shared/model/ApiVersion.java
+++ b/app/src/main/java/it/niedermann/owncloud/notes/shared/model/ApiVersion.java
@@ -42,10 +42,6 @@ public class ApiVersion implements Comparable<ApiVersion> {
         return minor;
     }
 
-    public String getOriginalVersion() {
-        return originalVersion;
-    }
-
     public static ApiVersion of(String versionString) {
         int major = 0, minor = 0;
         if (versionString != null) {
@@ -90,6 +86,9 @@ public class ApiVersion implements Comparable<ApiVersion> {
 //        return getMajor() >= 1 && getMinor() >= 2;
     }
 
+    /**
+     * Checks only the <strong>{@link #major}</strong> version.
+     */
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;
diff --git a/app/src/main/java/it/niedermann/owncloud/notes/shared/model/Capabilities.java b/app/src/main/java/it/niedermann/owncloud/notes/shared/model/Capabilities.java
index 5514a91b..06bd867d 100644
--- a/app/src/main/java/it/niedermann/owncloud/notes/shared/model/Capabilities.java
+++ b/app/src/main/java/it/niedermann/owncloud/notes/shared/model/Capabilities.java
@@ -1,103 +1,21 @@
 package it.niedermann.owncloud.notes.shared.model;
 
 import android.graphics.Color;
-import android.util.Log;
 
 import androidx.annotation.ColorInt;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
-import androidx.annotation.VisibleForTesting;
 
-import com.bumptech.glide.load.HttpException;
-import com.nextcloud.android.sso.exceptions.NextcloudHttpRequestFailedException;
-
-import org.json.JSONException;
-import org.json.JSONObject;
-
-import it.niedermann.android.util.ColorUtil;
-
-import static java.net.HttpURLConnection.HTTP_UNAVAILABLE;
-
-/**
- * This entity class is used to return relevant data of the HTTP response.
- */
 public class Capabilities {
 
-    private static final String TAG = Capabilities.class.getSimpleName();
-
-    private static final String JSON_OCS = "ocs";
-    private static final String JSON_OCS_META = "meta";
-    private static final String JSON_OCS_META_STATUSCODE = "statuscode";
-    private static final String JSON_OCS_DATA = "data";
-    private static final String JSON_OCS_DATA_CAPABILITIES = "capabilities";
-    private static final String JSON_OCS_DATA_CAPABILITIES_NOTES = "notes";
-    private static final String JSON_OCS_DATA_CAPABILITIES_NOTES_API_VERSION = "api_version";
-    private static final String JSON_OCS_DATA_CAPABILITIES_THEMING = "theming";
-    private static final String JSON_OCS_DATA_CAPABILITIES_THEMING_COLOR = "color";
-    private static final String JSON_OCS_DATA_CAPABILITIES_THEMING_COLOR_TEXT = "color-text";
-
     private String apiVersion = null;
-
     @ColorInt
-    private int color = -16743735;
+    private int color = -16743735; // #0082C9
     @ColorInt
-    private int textColor = -16777216;
+    private int textColor = Color.WHITE;
     @Nullable
     private String eTag;
 
-    public Capabilities() {
-
-    }
-
-    @VisibleForTesting
-    public Capabilities(@NonNull String response, @Nullable String eTag) throws NextcloudHttpRequestFailedException {
-        this.eTag = eTag;
-        final JSONObject ocs;
-        try {
-            ocs = new JSONObject(response).getJSONObject(JSON_OCS);
-            if (ocs.has(JSON_OCS_META)) {
-                final JSONObject meta = ocs.getJSONObject(JSON_OCS_META);
-                if (meta.has(JSON_OCS_META_STATUSCODE)) {
-                    if (meta.getInt(JSON_OCS_META_STATUSCODE) == HTTP_UNAVAILABLE) {
-                        Log.i(TAG, "Capabilities Endpoint: This instance is currently in maintenance mode.");
-                        throw new NextcloudHttpRequestFailedException(HTTP_UNAVAILABLE, new HttpException(HTTP_UNAVAILABLE));
-                    }
-                }
-            }
-            if (ocs.has(JSON_OCS_DATA)) {
-                final JSONObject data = ocs.getJSONObject(JSON_OCS_DATA);
-                if (data.has(JSON_OCS_DATA_CAPABILITIES)) {
-                    final JSONObject capabilities = data.getJSONObject(JSON_OCS_DATA_CAPABILITIES);
-                    if (capabilities.has(JSON_OCS_DATA_CAPABILITIES_NOTES)) {
-                        final JSONObject notes = capabilities.getJSONObject(JSON_OCS_DATA_CAPABILITIES_NOTES);
-                        if (notes.has(JSON_OCS_DATA_CAPABILITIES_NOTES_API_VERSION)) {
-                            this.apiVersion = notes.getString(JSON_OCS_DATA_CAPABILITIES_NOTES_API_VERSION);
-                        }
-                    }
-                    if (capabilities.has(JSON_OCS_DATA_CAPABILITIES_THEMING)) {
-                        final JSONObject theming = capabilities.getJSONObject(JSON_OCS_DATA_CAPABILITIES_THEMING);
-                        if (theming.has(JSON_OCS_DATA_CAPABILITIES_THEMING_COLOR)) {
-                            try {
-                                this.color = Color.parseColor(ColorUtil.INSTANCE.formatColorToParsableHexString(theming.getString(JSON_OCS_DATA_CAPABILITIES_THEMING_COLOR)));
-                            } catch (Exception e) {
-                                e.printStackTrace();
-                            }
-                        }
-                        if (theming.has(JSON_OCS_DATA_CAPABILITIES_THEMING_COLOR_TEXT)) {
-                            try {
-                                this.textColor = Color.parseColor(ColorUtil.INSTANCE.formatColorToParsableHexString(theming.getString(JSON_OCS_DATA_CAPABILITIES_THEMING_COLOR_TEXT)));
-                            } catch (Exception e) {
-                                e.printStackTrace();
-                            }
-                        }
-                    }
-                }
-            }
-        } catch (JSONException e) {
-            e.printStackTrace();
-        }
-    }
-
     public void setApiVersion(String apiVersion) {
         this.apiVersion = apiVersion;
     }
diff --git a/app/src/main/java/it/niedermann/owncloud/notes/shared/model/CategorySortingMethod.java b/app/src/main/java/it/niedermann/owncloud/notes/shared/model/CategorySortingMethod.java
index 94bcda38..6a36ade1 100644
--- a/app/src/main/java/it/niedermann/owncloud/notes/shared/model/CategorySortingMethod.java
+++ b/app/src/main/java/it/niedermann/owncloud/notes/shared/model/CategorySortingMethod.java
@@ -7,7 +7,7 @@ public enum CategorySortingMethod {
     private final int id;
     private final String title;  // sorting method OrderBy for SQL
 
-    /***
+    /**
      * Constructor
      * @param title given sorting method OrderBy
      */
@@ -16,7 +16,7 @@ public enum CategorySortingMethod {
         this.title = title;
     }
 
-    /***
+    /**
      * Retrieve the sorting method id represented in database
      * @return the sorting method id for the enum item
      */
@@ -24,7 +24,7 @@ public enum CategorySortingMethod {
         return this.id;
     }
 
-    /***
+    /**
      * Retrieve the sorting method order for SQL
      * @return the sorting method order for the enum item
      */
@@ -32,7 +32,7 @@ public enum CategorySortingMethod {
         return this.title;
     }
 
-    /***
+    /**
      * Retrieve the corresponding enum value with given the index (ordinal)
      * @param id the id of the corresponding enum value stored in DB
      * @return the corresponding enum item with the index (ordinal)
diff --git a/app/src/main/java/it/niedermann/owncloud/notes/shared/model/OcsResponse.java b/app/src/main/java/it/niedermann/owncloud/notes/shared/model/OcsResponse.java
new file mode 100644
index 00000000..0fea9a92
--- /dev/null
+++ b/app/src/main/java/it/niedermann/owncloud/notes/shared/model/OcsResponse.java
@@ -0,0 +1,30 @@
+package it.niedermann.owncloud.notes.shared.model;
+
+import com.google.gson.annotations.Expose;
+
+/**
+ * <a href="https://www.open-collaboration-services.org/">OpenCollaborationServices</a>
+ *
+ * @param <T> defines the payload of this {@link OcsResponse}.
+ */
+public class OcsResponse<T> {
+
+    @Expose
+    public OcsWrapper<T> ocs;
+
+    public static class OcsWrapper<T> {
+        @Expose
+        public OcsMeta meta;
+        @Expose
+        public T data;
+    }
+
+    public static class OcsMeta {
+        @Expose
+        public String status;
+        @Expose
+        public int statuscode;
+        @Expose
+        public String message;
+    }
+}
\ No newline at end of file
diff --git a/app/src/main/java/it/niedermann/owncloud/notes/shared/model/OcsUser.java b/app/src/main/java/it/niedermann/owncloud/notes/shared/model/OcsUser.java
new file mode 100644
index 00000000..9248abdf
--- /dev/null
+++ b/app/src/main/java/it/niedermann/owncloud/notes/shared/model/OcsUser.java
@@ -0,0 +1,16 @@
+package it.niedermann.owncloud.notes.shared.model;
+
+import com.google.gson.annotations.Expose;
+import com.google.gson.annotations.SerializedName;
+
+/**
+ * Equivalent of an <code><a href="https://docs.nextcloud.com/server/latest/developer_manual/client_apis/OCS/ocs-api-overview.html?highlight=ocs#user-metadata">OcsUser</a></code>
+ */
+public class OcsUser {
+    @Expose
+    @SerializedName("id")
+    public String userId;
+    @Expose
+    @SerializedName("displayname")
+    public String displayName;
+}
\ No newline at end of file
diff --git a/app/src/main/java/it/niedermann/owncloud/notes/shared/util/ApiVersionUtil.java b/app/src/main/java/it/niedermann/owncloud/notes/shared/util/ApiVersionUtil.java
new file mode 100644
index 00000000..57788472
--- /dev/null
+++ b/app/src/main/java/it/niedermann/owncloud/notes/shared/util/ApiVersionUtil.java
@@ -0,0 +1,105 @@
+package it.niedermann.owncloud.notes.shared.util;
+
+import android.text.TextUtils;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import org.json.JSONArray;
+import org.json.JSONException;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Objects;
+import java.util.stream.Collectors;
+
+import it.niedermann.owncloud.notes.shared.model.ApiVersion;
+
+public class ApiVersionUtil {
+
+    private ApiVersionUtil() {
+        throw new UnsupportedOperationException("Do not instantiate this util class.");
+    }
+
+    /**
+     * @return a {@link Collection} of all valid {@link ApiVersion}s which have been found in {@param raw}.
+     */
+    @NonNull
+    public static Collection<ApiVersion> parse(@Nullable String raw) {
+        if (TextUtils.isEmpty(raw)) {
+            return Collections.emptyList();
+        }
+
+        JSONArray a;
+        try {
+            a = new JSONArray(raw);
+        } catch (JSONException e) {
+            try {
+                a = new JSONArray("[" + raw + "]");
+            } catch (JSONException e1) {
+                return Collections.emptyList();
+            }
+        }
+
+        final Collection<ApiVersion> result = new ArrayList<>();
+        for (int i = 0; i < a.length(); i++) {
+            try {
+                final ApiVersion version = ApiVersion.of(a.getString(i));
+                if (version.getMajor() != 0 || version.getMinor() != 0) {
+                    result.add(version);
+                }
+            } catch (Exception ignored) {
+            }
+        }
+        return result;
+    }
+
+    /**
+     * @return a serialized {@link String} of the given {@param apiVersions} or <code>null</code>.
+     */
+    @Nullable
+    public static String serialize(@Nullable Collection<ApiVersion> apiVersions) {
+        if (apiVersions == null || apiVersions.isEmpty()) {
+            return null;
+        }
+        return "[" +
+                apiVersions
+                        .stream()
+                        .filter(Objects::nonNull)
+                        .map(v -> v.getMajor() + "." + v.getMinor())
+                        .collect(Collectors.joining(","))
+                + "]";
+    }
+
+    @Nullable
+    public static String sanitize(@Nullable String raw) {
+        return serialize(parse(raw));
+    }
+
+    /**
+     * @return the highest {@link ApiVersion} that is supported by the server according to {@param raw},
+     * whose major version is also supported by this app (see {@link ApiVersion#SUPPORTED_API_VERSIONS}).
+     * Returns <code>null</code> if no better version could be found.
+     */
+    @Nullable
+    public static ApiVersion getPreferredApiVersion(@Nullable String raw) {
+        return parse(raw)
+                .stream()
+                .filter(version -> Arrays.asList(ApiVersion.SUPPORTED_API_VERSIONS).contains(version))
+                .max((o1, o2) -> {
+                    if (o2.getMajor() > o1.getMajor()) {
+                        return -1;
+                    } else if (o2.getMajor() < o1.getMajor()) {
+                        return 1;
+                    } else if (o2.getMinor() > o1.getMinor()) {
+                        return -1;
+                    } else if (o2.getMinor() < o1.getMinor()) {
+                        return 1;
+                    }
+                    return 0;
+                })
+                .orElse(null);
+    }
+}
diff --git a/app/src/main/java/it/niedermann/owncloud/notes/shared/util/CustomAppGlideModule.java b/app/src/main/java/it/niedermann/owncloud/notes/shared/util/CustomAppGlideModule.java
index 03eb1097..35625119 100644
--- a/app/src/main/java/it/niedermann/owncloud/notes/shared/util/CustomAppGlideModule.java
+++ b/app/src/main/java/it/niedermann/owncloud/notes/shared/util/CustomAppGlideModule.java
@@ -1,18 +1,37 @@
 package it.niedermann.owncloud.notes.shared.util;
 
 import android.content.Context;
+import android.util.Log;
 
 import androidx.annotation.NonNull;
+import androidx.annotation.UiThread;
 
 import com.bumptech.glide.Glide;
 import com.bumptech.glide.Registry;
 import com.bumptech.glide.annotation.GlideModule;
 import com.bumptech.glide.module.AppGlideModule;
 
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
 @GlideModule
 public class CustomAppGlideModule extends AppGlideModule {
+
+    private static final String TAG = CustomAppGlideModule.class.getSimpleName();
+    private static final ExecutorService clearDiskCacheExecutor = Executors.newSingleThreadExecutor();
+
     @Override
     public void registerComponents(@NonNull Context context, @NonNull Glide glide, @NonNull Registry registry) {
         super.registerComponents(context, glide, registry);
     }
+
+    @UiThread
+    public static void clearCache(@NonNull Context context) {
+        Log.i(TAG, "Clearing Glide memory cache");
+        Glide.get(context).clearMemory();
+        clearDiskCacheExecutor.submit(() -> {
+            Log.i(TAG, "Clearing Glide disk cache");
+            Glide.get(context.getApplicationContext()).clearDiskCache();
+        });
+    }
 }
\ No newline at end of file
diff --git a/app/src/main/java/it/niedermann/owncloud/notes/shared/util/DatabaseIndexUtil.java b/app/src/main/java/it/niedermann/owncloud/notes/shared/util/DatabaseIndexUtil.java
deleted file mode 100644
index 8506c713..00000000
--- a/app/src/main/java/it/niedermann/owncloud/notes/shared/util/DatabaseIndexUtil.java
+++ /dev/null
@@ -1,41 +0,0 @@
-package it.niedermann.owncloud.notes.shared.util;
-
-import android.database.Cursor;
-import android.database.sqlite.SQLiteDatabase;
-import android.util.Log;
-
-import androidx.annotation.NonNull;
-import androidx.sqlite.db.SupportSQLiteDatabase;
-
-public class DatabaseIndexUtil {
-
-    private static final String TAG = DatabaseIndexUtil.class.getSimpleName();
-
-    private DatabaseIndexUtil() {
-
-    }
-
-    public static void createIndex(@NonNull SupportSQLiteDatabase db, @NonNull String table, @NonNull String... columns) {
-        for (String column : columns) {
-            createIndex(db, table, column);
-        }
-    }
-
-    public static void createIndex(@NonNull SupportSQLiteDatabase db, @NonNull String table, @NonNull String column) {
-        String indexName = table + "_" + column + "_idx";
-        Log.v(TAG, "Creating database index: CREATE INDEX IF NOT EXISTS " + indexName + " ON " + table + "(" + column + ")");
-        db.execSQL("CREATE INDEX " + indexName + " ON " + table + "(" + column + ")");
-    }
-
-    public static void dropIndexes(@NonNull SupportSQLiteDatabase db) {
-        try (Cursor c = db.query("SELECT name, sql FROM sqlite_master WHERE type = 'index'")) {
-            while (c.moveToNext()) {
-                // Skip automatic indexes which we can't drop manually
-                if (c.getString(1) != null) {
-                    Log.v(TAG, "Deleting database index: DROP INDEX " + c.getString(0));
-                    db.execSQL("DROP INDEX " + c.getString(0));
-                }
-            }
-        }
-    }
-}
diff --git a/app/src/main/java/it/niedermann/owncloud/notes/shared/util/DeviceCredentialUtil.java b/app/src/main/java/it/niedermann/owncloud/notes/shared/util/DeviceCredentialUtil.java
index 034eea5a..14163e91 100644
--- a/app/src/main/java/it/niedermann/owncloud/notes/shared/util/DeviceCredentialUtil.java
+++ b/app/src/main/java/it/niedermann/owncloud/notes/shared/util/DeviceCredentialUtil.java
@@ -12,7 +12,7 @@ public class DeviceCredentialUtil {
     private static final String TAG = DeviceCredentialUtil.class.getSimpleName();
 
     private DeviceCredentialUtil() {
-        // utility class -> private constructor
+        throw new UnsupportedOperationException("Do not instantiate this util class.");
     }
 
     public static boolean areCredentialsAvailable(Context context) {
diff --git a/app/src/main/java/it/niedermann/owncloud/notes/shared/util/DisplayUtils.java b/app/src/main/java/it/niedermann/owncloud/notes/shared/util/DisplayUtils.java
index ad6b6793..06cbf57d 100644
--- a/app/src/main/java/it/niedermann/owncloud/notes/shared/util/DisplayUtils.java
+++ b/app/src/main/java/it/niedermann/owncloud/notes/shared/util/DisplayUtils.java
@@ -2,27 +2,21 @@ package it.niedermann.owncloud.notes.shared.util;
 
 import android.content.Context;
 import android.content.res.Resources;
-import android.graphics.Color;
-import android.text.Spannable;
-import android.text.TextPaint;
-import android.text.TextUtils;
-import android.text.style.MetricAffectingSpan;
+import android.graphics.Rect;
+import android.os.Build;
+import android.util.TypedValue;
+import android.view.View;
+import android.view.WindowInsets;
 
-import androidx.annotation.ColorInt;
 import androidx.annotation.NonNull;
-import androidx.annotation.Nullable;
-import androidx.core.content.ContextCompat;
+import androidx.core.view.ViewCompat;
+import androidx.core.view.WindowInsetsCompat;
 
 import java.util.Collection;
 import java.util.List;
-import java.util.regex.Matcher;
-import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 
-import it.niedermann.android.util.ColorUtil;
-import it.niedermann.owncloud.notes.NotesApplication;
 import it.niedermann.owncloud.notes.R;
-import it.niedermann.owncloud.notes.branding.BrandingUtil;
 import it.niedermann.owncloud.notes.main.navigation.NavigationAdapter;
 import it.niedermann.owncloud.notes.main.navigation.NavigationItem;
 import it.niedermann.owncloud.notes.persistence.entity.CategoryWithNotesCount;
@@ -30,7 +24,7 @@ import it.niedermann.owncloud.notes.persistence.entity.CategoryWithNotesCount;
 public class DisplayUtils {
 
     private DisplayUtils() {
-
+        throw new UnsupportedOperationException("Do not instantiate this util class.");
     }
 
     public static List<NavigationItem.CategoryNavigationItem> convertToCategoryNavigationItem(@NonNull Context context, @NonNull Collection<CategoryWithNotesCount> counter) {
@@ -52,4 +46,29 @@ public class DisplayUtils {
         }
         return new NavigationItem.CategoryNavigationItem("category:" + counter.getCategory(), counter.getCategory(), counter.getTotalNotes(), icon, counter.getAccountId(), counter.getCategory());
     }
+
+    /**
+     * Detect if the soft keyboard is open.
+     * On API prior to 30 we fall back to workaround which might be less reliable
+     *
+     * @param parentView View
+     * @return keyboardVisibility Boolean
+     */
+    public static boolean isSoftKeyboardVisible(@NonNull View parentView) {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
+            final WindowInsetsCompat insets = ViewCompat.getRootWindowInsets(parentView);
+            if (insets != null) {
+                return insets.isVisible(WindowInsets.Type.ime());
+            }
+        }
+
+        //Arbitrary keyboard height
+        final int defaultKeyboardHeightDP = 100;
+        final int EstimatedKeyboardDP = defaultKeyboardHeightDP + (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP ? 48 : 0);
+        final Rect rect = new Rect();
+        final int estimatedKeyboardHeight = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, EstimatedKeyboardDP, parentView.getResources().getDisplayMetrics());
+        parentView.getWindowVisibleDisplayFrame(rect);
+        final int heightDiff = parentView.getRootView().getHeight() - (rect.bottom - rect.top);
+        return heightDiff >= estimatedKeyboardHeight;
+    }
 }
diff --git a/app/src/main/java/it/niedermann/owncloud/notes/shared/util/NoteUtil.java b/app/src/main/java/it/niedermann/owncloud/notes/shared/util/NoteUtil.java
index e5b8afae..3d5a118c 100644
--- a/app/src/main/java/it/niedermann/owncloud/notes/shared/util/NoteUtil.java
+++ b/app/src/main/java/it/niedermann/owncloud/notes/shared/util/NoteUtil.java
@@ -22,7 +22,7 @@ public class NoteUtil {
     public static final String EXCERPT_LINE_SEPARATOR = "   ";
 
     private NoteUtil() {
-
+        throw new UnsupportedOperationException("Do not instantiate this util class.");
     }
 
     /**
@@ -117,7 +117,7 @@ public class NoteUtil {
                 line = removeMarkdown(lines[currentLine]);
             }
         } else {
-            line = content;
+            line = removeMarkdown(content);
         }
         return line;
     }
diff --git a/app/src/main/java/it/niedermann/owncloud/notes/shared/util/NotesColorUtil.java b/app/src/main/java/it/niedermann/owncloud/notes/shared/util/NotesColorUtil.java
index a445208b..42aaf79d 100644
--- a/app/src/main/java/it/niedermann/owncloud/notes/shared/util/NotesColorUtil.java
+++ b/app/src/main/java/it/niedermann/owncloud/notes/shared/util/NotesColorUtil.java
@@ -14,6 +14,7 @@ public final class NotesColorUtil {
     private static final Map<ColorPair, Boolean> CONTRAST_RATIO_SUFFICIENT_CACHE = new HashMap<>();
 
     private NotesColorUtil() {
+        throw new UnsupportedOperationException("Do not instantiate this util class.");
     }
 
     public static boolean contrastRatioIsSufficient(@ColorInt int colorOne, @ColorInt int colorTwo) {
diff --git a/app/src/main/java/it/niedermann/owncloud/notes/shared/util/SSOUtil.java b/app/src/main/java/it/niedermann/owncloud/notes/shared/util/SSOUtil.java
index da529136..1e2542b0 100644
--- a/app/src/main/java/it/niedermann/owncloud/notes/shared/util/SSOUtil.java
+++ b/app/src/main/java/it/niedermann/owncloud/notes/shared/util/SSOUtil.java
@@ -19,7 +19,7 @@ public class SSOUtil {
     private static final String TAG = SSOUtil.class.getSimpleName();
 
     private SSOUtil() {
-
+        throw new UnsupportedOperationException("Do not instantiate this util class.");
     }
 
     /**
diff --git a/app/src/main/java/it/niedermann/owncloud/notes/shared/util/ShareUtil.java b/app/src/main/java/it/niedermann/owncloud/notes/shared/util/ShareUtil.java
index 115d18dd..4b7aebd9 100644
--- a/app/src/main/java/it/niedermann/owncloud/notes/shared/util/ShareUtil.java
+++ b/app/src/main/java/it/niedermann/owncloud/notes/shared/util/ShareUtil.java
@@ -14,6 +14,11 @@ import it.niedermann.android.markdown.MarkdownUtil;
 import static android.content.ClipDescription.MIMETYPE_TEXT_PLAIN;
 
 public class ShareUtil {
+
+    private ShareUtil() {
+        throw new UnsupportedOperationException("Do not instantiate this util class.");
+    }
+
     public static void openShareDialog(@NonNull Context context, @Nullable String subject, @Nullable String text) {
         context.startActivity(Intent.createChooser(new Intent()
                 .setAction(Intent.ACTION_SEND)
diff --git a/app/src/main/java/it/niedermann/owncloud/notes/shared/util/SupportUtil.java b/app/src/main/java/it/niedermann/owncloud/notes/shared/util/SupportUtil.java
index 8bf80cb9..27fec716 100644
--- a/app/src/main/java/it/niedermann/owncloud/notes/shared/util/SupportUtil.java
+++ b/app/src/main/java/it/niedermann/owncloud/notes/shared/util/SupportUtil.java
@@ -13,7 +13,7 @@ import androidx.core.text.HtmlCompat;
 public class SupportUtil {
 
     private SupportUtil() {
-
+        throw new UnsupportedOperationException("Do not instantiate this util class.");
     }
 
     /**