diff --git a/app/build.gradle b/app/build.gradle
index 66c1b07..6d2b6ee 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -1,8 +1,7 @@
 apply plugin: 'com.android.application'
 
 android {
-    compileSdkVersion 25
-    buildToolsVersion '26.0.3'
+    compileSdkVersion 29
 
     testOptions {
         unitTests.returnDefaultValues = true
@@ -11,9 +10,10 @@ android {
     defaultConfig {
         applicationId "org.secuso.privacyfriendlysudoku"
         minSdkVersion 16
-        targetSdkVersion 25
+        targetSdkVersion 29
         versionCode 6
         versionName "2.1.2"
+        vectorDrawables.useSupportLibrary = true
     }
     buildTypes {
         release {
@@ -22,19 +22,19 @@ android {
         }
     }
     compileOptions {
-        sourceCompatibility JavaVersion.VERSION_1_7
-        targetCompatibility JavaVersion.VERSION_1_7
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
     }
 }
 
 dependencies {
-    compile fileTree(include: ['*.jar'], dir: 'libs')
-    testCompile 'junit:junit:4.12'
-    compile 'com.android.support:support-compat:25.3.1'
-    compile 'com.android.support:support-v4:25.3.1'
-    compile 'com.android.support:support-v13:25.3.1'
-    compile 'com.android.support:appcompat-v7:25.3.1'
-    compile 'com.android.support:design:25.3.1'
-    compile 'com.android.support:support-core-ui:25.3.1'
-    compile 'com.android.support:support-core-utils:25.3.1'
+    implementation fileTree(include: ['*.jar'], dir: 'libs')
+    testImplementation 'junit:junit:4.12'
+    implementation 'androidx.core:core:1.2.0'
+    implementation 'androidx.legacy:legacy-support-v4:1.0.0'
+    implementation 'androidx.legacy:legacy-support-v13:1.0.0'
+    implementation 'androidx.appcompat:appcompat:1.1.0'
+    implementation 'com.google.android.material:material:1.1.0'
+    implementation 'androidx.legacy:legacy-support-core-ui:1.0.0'
+    implementation 'androidx.legacy:legacy-support-core-utils:1.0.0'
 }
diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index 290ca0e..9d32955 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -2,12 +2,15 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="org.secuso.privacyfriendlysudoku.ui.view">
 
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE"/>
+
     <application
         android:allowBackup="true"
         android:icon="@mipmap/ic_launcher"
         android:label="@string/app_name"
         android:supportsRtl="true"
-        android:theme="@style/AppTheme">
+        android:theme="@style/AppTheme"
+        android:name="org.secuso.privacyfriendlysudoku.SudokuApp">
         <activity
             android:name="org.secuso.privacyfriendlysudoku.ui.SplashActivity"
             android:theme="@style/SplashTheme">
diff --git a/app/src/main/java/org/secuso/privacyfriendlysudoku/SudokuApp.java b/app/src/main/java/org/secuso/privacyfriendlysudoku/SudokuApp.java
new file mode 100644
index 0000000..cd98737
--- /dev/null
+++ b/app/src/main/java/org/secuso/privacyfriendlysudoku/SudokuApp.java
@@ -0,0 +1,32 @@
+package org.secuso.privacyfriendlysudoku;
+
+import android.app.Application;
+import android.app.NotificationChannel;
+import android.app.NotificationChannelGroup;
+import android.app.NotificationManager;
+import android.content.Context;
+import android.os.Build;
+
+import androidx.appcompat.app.AppCompatDelegate;
+
+public class SudokuApp extends Application {
+
+    public static final String CHANNEL_ID = "sudoku.0";
+
+    @Override
+    public void onCreate() {
+        super.onCreate();
+        AppCompatDelegate.setCompatVectorFromResourcesEnabled(true);
+
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            // channels
+            NotificationChannel channel = new NotificationChannel(CHANNEL_ID, "Default", NotificationManager.IMPORTANCE_LOW);
+
+            NotificationManager notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
+            if (notificationManager != null) {
+                notificationManager.createNotificationChannel(channel);
+            }
+        }
+    }
+
+}
diff --git a/app/src/main/java/org/secuso/privacyfriendlysudoku/controller/GeneratorService.java b/app/src/main/java/org/secuso/privacyfriendlysudoku/controller/GeneratorService.java
index 32f78df..f6dbead 100644
--- a/app/src/main/java/org/secuso/privacyfriendlysudoku/controller/GeneratorService.java
+++ b/app/src/main/java/org/secuso/privacyfriendlysudoku/controller/GeneratorService.java
@@ -2,32 +2,25 @@ package org.secuso.privacyfriendlysudoku.controller;
 
 import android.app.IntentService;
 import android.app.PendingIntent;
-import android.app.Service;
 import android.content.Intent;
-import android.os.Handler;
-import android.os.IBinder;
-import android.os.Looper;
-import android.support.annotation.IntDef;
-import android.support.annotation.Nullable;
-import android.support.v4.content.ContextCompat;
-import android.support.v7.app.NotificationCompat;
+import androidx.annotation.Nullable;
+import androidx.core.app.NotificationCompat;
+import androidx.core.content.ContextCompat;
 import android.util.Log;
 import android.util.Pair;
 
+import org.secuso.privacyfriendlysudoku.SudokuApp;
 import org.secuso.privacyfriendlysudoku.controller.database.DatabaseHelper;
 import org.secuso.privacyfriendlysudoku.controller.database.model.Level;
 import org.secuso.privacyfriendlysudoku.controller.qqwing.Action;
 import org.secuso.privacyfriendlysudoku.controller.qqwing.PrintStyle;
 import org.secuso.privacyfriendlysudoku.controller.qqwing.QQWing;
 import org.secuso.privacyfriendlysudoku.controller.qqwing.Symmetry;
-import org.secuso.privacyfriendlysudoku.game.GameBoard;
 import org.secuso.privacyfriendlysudoku.game.GameDifficulty;
 import org.secuso.privacyfriendlysudoku.game.GameType;
 import org.secuso.privacyfriendlysudoku.ui.MainActivity;
 import org.secuso.privacyfriendlysudoku.ui.view.R;
 
-import java.util.Date;
-import java.util.IllegalFormatCodePointException;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.concurrent.atomic.AtomicBoolean;
@@ -255,7 +248,7 @@ public class GeneratorService extends IntentService {
     }
 
     private void showNotification(GameType gameType, GameDifficulty gameDifficulty) {
-        NotificationCompat.Builder builder = new NotificationCompat.Builder(this);
+        NotificationCompat.Builder builder = new NotificationCompat.Builder(this, SudokuApp.CHANNEL_ID);
         builder.setContentTitle(getString(R.string.app_name));
         builder.setContentText(getString(R.string.generating));
         builder.setSubText(getString(gameType.getStringResID()) + ", " + getString(gameDifficulty.getStringResID()));
diff --git a/app/src/main/java/org/secuso/privacyfriendlysudoku/controller/database/DatabaseHelper.java b/app/src/main/java/org/secuso/privacyfriendlysudoku/controller/database/DatabaseHelper.java
index 59fdae0..85dd131 100644
--- a/app/src/main/java/org/secuso/privacyfriendlysudoku/controller/database/DatabaseHelper.java
+++ b/app/src/main/java/org/secuso/privacyfriendlysudoku/controller/database/DatabaseHelper.java
@@ -39,7 +39,7 @@ public class DatabaseHelper extends SQLiteOpenHelper {
         onUpgrade(db, oldVersion, newVersion);
     }
 
-    public List<Level> getLevels(GameDifficulty difficulty, GameType gameType) {
+    public synchronized List<Level> getLevels(GameDifficulty difficulty, GameType gameType) {
         if(difficulty == null || gameType == null) {
             throw new IllegalArgumentException("Arguments may not be null");
         }
@@ -72,7 +72,7 @@ public class DatabaseHelper extends SQLiteOpenHelper {
         return levelList;
     }
 
-    public Level getLevel(GameDifficulty difficulty, GameType gameType) {
+    public synchronized Level getLevel(GameDifficulty difficulty, GameType gameType) {
         List<Level> levelList = getLevels(difficulty, gameType);
         if(levelList.size() == 0) {
             throw new IllegalArgumentException("There is no level");
@@ -80,7 +80,7 @@ public class DatabaseHelper extends SQLiteOpenHelper {
         return levelList.get(0);
     }
 
-    public void deleteLevel(int id) {
+    public synchronized void deleteLevel(int id) {
         SQLiteDatabase database = getWritableDatabase();
 
         String selection = LevelColumns._ID + " = ?";
@@ -89,7 +89,7 @@ public class DatabaseHelper extends SQLiteOpenHelper {
         database.delete(LevelColumns.TABLE_NAME, selection, selectionArgs);
     }
 
-    public long addLevel(Level level) {
+    public synchronized long addLevel(Level level) {
         SQLiteDatabase database = getWritableDatabase();
         return database.insert(LevelColumns.TABLE_NAME, null, LevelColumns.getValues(level));
     }
diff --git a/app/src/main/java/org/secuso/privacyfriendlysudoku/game/GameCell.java b/app/src/main/java/org/secuso/privacyfriendlysudoku/game/GameCell.java
index 62dbcc4..de2a4f0 100644
--- a/app/src/main/java/org/secuso/privacyfriendlysudoku/game/GameCell.java
+++ b/app/src/main/java/org/secuso/privacyfriendlysudoku/game/GameCell.java
@@ -2,14 +2,11 @@ package org.secuso.privacyfriendlysudoku.game;
 
 import android.os.Parcel;
 import android.os.Parcelable;
-import android.support.annotation.NonNull;
+import androidx.annotation.NonNull;
 
 import java.util.Arrays;
-import java.util.Collection;
-import java.util.Iterator;
 import java.util.LinkedList;
 import java.util.List;
-import java.util.ListIterator;
 
 import org.secuso.privacyfriendlysudoku.game.listener.IModelChangedListener;
 
diff --git a/app/src/main/java/org/secuso/privacyfriendlysudoku/game/GameDifficulty.java b/app/src/main/java/org/secuso/privacyfriendlysudoku/game/GameDifficulty.java
index fbf9f9c..f296149 100644
--- a/app/src/main/java/org/secuso/privacyfriendlysudoku/game/GameDifficulty.java
+++ b/app/src/main/java/org/secuso/privacyfriendlysudoku/game/GameDifficulty.java
@@ -2,7 +2,7 @@ package org.secuso.privacyfriendlysudoku.game;
 
 import android.os.Parcel;
 import android.os.Parcelable;
-import android.support.annotation.StringRes;
+import androidx.annotation.StringRes;
 
 import java.util.LinkedList;
 
diff --git a/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/AboutActivity.java b/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/AboutActivity.java
index 065edf9..e42d898 100644
--- a/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/AboutActivity.java
+++ b/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/AboutActivity.java
@@ -2,7 +2,7 @@ package org.secuso.privacyfriendlysudoku.ui;
 
 import android.graphics.Color;
 import android.graphics.drawable.ColorDrawable;
-import android.support.v7.app.AppCompatActivity;
+import androidx.appcompat.app.AppCompatActivity;
 import android.os.Bundle;
 import android.text.method.LinkMovementMethod;
 import android.view.MenuItem;
@@ -22,7 +22,7 @@ public class AboutActivity extends BaseActivity {
         ((TextView)findViewById(R.id.githubURL)).setMovementMethod(LinkMovementMethod.getInstance());
         ((TextView)findViewById(R.id.textFieldVersionName)).setText(BuildConfig.VERSION_NAME);
 
-        android.support.v7.app.ActionBar actionBar = getSupportActionBar();
+        androidx.appcompat.app.ActionBar actionBar = getSupportActionBar();
         actionBar.setTitle(R.string.menu_about);
         actionBar.setDisplayHomeAsUpEnabled(true);
         actionBar.setBackgroundDrawable(new ColorDrawable(Color.parseColor("#024265")));
diff --git a/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/AppCompatPreferenceActivity.java b/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/AppCompatPreferenceActivity.java
index ac22c1a..4133998 100644
--- a/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/AppCompatPreferenceActivity.java
+++ b/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/AppCompatPreferenceActivity.java
@@ -3,11 +3,11 @@ package org.secuso.privacyfriendlysudoku.ui;
 import android.content.res.Configuration;
 import android.os.Bundle;
 import android.preference.PreferenceActivity;
-import android.support.annotation.LayoutRes;
-import android.support.annotation.Nullable;
-import android.support.v7.app.ActionBar;
-import android.support.v7.app.AppCompatDelegate;
-import android.support.v7.widget.Toolbar;
+import androidx.annotation.LayoutRes;
+import androidx.annotation.Nullable;
+import androidx.appcompat.app.ActionBar;
+import androidx.appcompat.app.AppCompatDelegate;
+import androidx.appcompat.widget.Toolbar;
 import android.view.MenuInflater;
 import android.view.View;
 import android.view.ViewGroup;
diff --git a/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/BaseActivity.java b/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/BaseActivity.java
index 02d9ea9..38750a5 100644
--- a/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/BaseActivity.java
+++ b/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/BaseActivity.java
@@ -2,8 +2,8 @@ package org.secuso.privacyfriendlysudoku.ui;
 
 import android.os.Bundle;
 import android.os.Handler;
-import android.preference.PreferenceManager;
-import android.support.v7.app.AppCompatActivity;
+
+import androidx.appcompat.app.AppCompatActivity;
 import android.view.View;
 
 import org.secuso.privacyfriendlysudoku.ui.view.R;
diff --git a/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/GameActivity.java b/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/GameActivity.java
index 402a652..ece965e 100644
--- a/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/GameActivity.java
+++ b/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/GameActivity.java
@@ -12,12 +12,12 @@ import android.graphics.Point;
 import android.os.Bundle;
 import android.preference.PreferenceActivity;
 import android.preference.PreferenceManager;
-import android.support.design.widget.NavigationView;
-import android.support.v4.view.GravityCompat;
-import android.support.v4.widget.DrawerLayout;
-import android.support.v7.app.ActionBarDrawerToggle;
-import android.support.v7.app.AppCompatActivity;
-import android.support.v7.widget.Toolbar;
+import com.google.android.material.navigation.NavigationView;
+import androidx.core.view.GravityCompat;
+import androidx.drawerlayout.widget.DrawerLayout;
+import androidx.appcompat.app.ActionBarDrawerToggle;
+import androidx.appcompat.app.AppCompatActivity;
+import androidx.appcompat.widget.Toolbar;
 import android.view.Gravity;
 import android.view.Menu;
 import android.view.MenuItem;
@@ -27,7 +27,6 @@ import android.widget.Button;
 import android.widget.LinearLayout;
 import android.widget.RatingBar;
 import android.widget.TextView;
-import android.widget.Toast;
 
 import org.secuso.privacyfriendlysudoku.controller.GameController;
 import org.secuso.privacyfriendlysudoku.controller.GameStateManager;
@@ -46,10 +45,8 @@ import org.secuso.privacyfriendlysudoku.ui.view.SudokuKeyboardLayout;
 import org.secuso.privacyfriendlysudoku.ui.view.SudokuSpecialButtonLayout;
 import org.secuso.privacyfriendlysudoku.ui.view.WinDialog;
 
-import java.util.IllegalFormatCodePointException;
 import java.util.LinkedList;
 import java.util.List;
-import java.util.concurrent.RunnableFuture;
 
 public class GameActivity extends BaseActivity implements NavigationView.OnNavigationItemSelectedListener, IGameSolvedListener ,ITimerListener, IHintDialogFragmentListener, IResetDialogFragmentListener {
 
diff --git a/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/HelpActivity.java b/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/HelpActivity.java
index 161005d..d731b12 100644
--- a/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/HelpActivity.java
+++ b/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/HelpActivity.java
@@ -2,29 +2,18 @@ package org.secuso.privacyfriendlysudoku.ui;
 
 
 import android.annotation.TargetApi;
-import android.content.Context;
-import android.content.Intent;
-import android.content.res.Configuration;
-import android.media.Ringtone;
-import android.media.RingtoneManager;
-import android.net.Uri;
 import android.os.Build;
 import android.os.Bundle;
 import android.preference.ListPreference;
 import android.preference.Preference;
 import android.preference.PreferenceActivity;
-import android.support.v7.app.ActionBar;
+import androidx.appcompat.app.ActionBar;
 import android.preference.PreferenceFragment;
 import android.preference.PreferenceManager;
-import android.preference.RingtonePreference;
-import android.text.TextUtils;
 import android.view.MenuItem;
-import android.view.View;
 
 import org.secuso.privacyfriendlysudoku.ui.view.R;
 
-import java.util.List;
-
 /**
  * A {@link PreferenceActivity} that presents a set of application settings. On
  * handset devices, settings are presented as a single list. On tablets,
diff --git a/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/LoadGameActivity.java b/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/LoadGameActivity.java
index 0ead53c..f04fa0b 100644
--- a/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/LoadGameActivity.java
+++ b/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/LoadGameActivity.java
@@ -45,7 +45,7 @@ public class LoadGameActivity extends BaseActivity implements IDeleteDialogFragm
 
         setContentView(R.layout.activity_load_game);
 
-        android.support.v7.app.ActionBar actionBar = getSupportActionBar();
+        androidx.appcompat.app.ActionBar actionBar = getSupportActionBar();
         actionBar.setTitle(R.string.menu_continue_game);
         actionBar.setDisplayHomeAsUpEnabled(true);
 
diff --git a/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/MainActivity.java b/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/MainActivity.java
index 6aa6527..70878d3 100644
--- a/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/MainActivity.java
+++ b/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/MainActivity.java
@@ -1,25 +1,20 @@
 package org.secuso.privacyfriendlysudoku.ui;
 
-import android.app.Activity;
-import android.app.AlertDialog;
-import android.app.Dialog;
-import android.app.DialogFragment;
-import android.content.DialogInterface;
 import android.content.Intent;
 import android.content.SharedPreferences;
 import android.os.Bundle;
 import android.preference.PreferenceActivity;
 import android.preference.PreferenceManager;
-import android.support.design.widget.NavigationView;
-import android.support.v4.app.Fragment;
-import android.support.v4.app.FragmentManager;
-import android.support.v4.app.FragmentPagerAdapter;
-import android.support.v4.view.GravityCompat;
-import android.support.v4.view.ViewPager;
-import android.support.v4.widget.DrawerLayout;
-import android.support.v7.app.ActionBarDrawerToggle;
-import android.support.v7.app.AppCompatActivity;
-import android.support.v7.widget.Toolbar;
+import com.google.android.material.navigation.NavigationView;
+import androidx.fragment.app.Fragment;
+import androidx.fragment.app.FragmentManager;
+import androidx.fragment.app.FragmentPagerAdapter;
+import androidx.core.view.GravityCompat;
+import androidx.viewpager.widget.ViewPager;
+import androidx.drawerlayout.widget.DrawerLayout;
+import androidx.appcompat.app.ActionBarDrawerToggle;
+import androidx.appcompat.app.AppCompatActivity;
+import androidx.appcompat.widget.Toolbar;
 import android.view.LayoutInflater;
 import android.view.MenuItem;
 import android.view.View;
@@ -37,7 +32,6 @@ import org.secuso.privacyfriendlysudoku.game.GameDifficulty;
 import org.secuso.privacyfriendlysudoku.game.GameType;
 import org.secuso.privacyfriendlysudoku.ui.view.R;
 
-import java.io.Serializable;
 import java.util.LinkedList;
 import java.util.List;
 
diff --git a/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/SettingsActivity.java b/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/SettingsActivity.java
index e3a80c1..448b560 100644
--- a/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/SettingsActivity.java
+++ b/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/SettingsActivity.java
@@ -9,7 +9,7 @@ import android.os.Bundle;
 import android.preference.ListPreference;
 import android.preference.Preference;
 import android.preference.PreferenceActivity;
-import android.support.v7.app.ActionBar;
+import androidx.appcompat.app.ActionBar;
 import android.preference.PreferenceFragment;
 import android.preference.PreferenceManager;
 import android.view.MenuItem;
diff --git a/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/SplashActivity.java b/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/SplashActivity.java
index c1df161..032fc39 100644
--- a/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/SplashActivity.java
+++ b/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/SplashActivity.java
@@ -2,7 +2,7 @@ package org.secuso.privacyfriendlysudoku.ui;
 
 import android.content.Intent;
 import android.os.Bundle;
-import android.support.v7.app.AppCompatActivity;
+import androidx.appcompat.app.AppCompatActivity;
 
 /**
  * Created by yonjuni on 22.10.16.
diff --git a/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/StatsActivity.java b/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/StatsActivity.java
index fe29654..1119d5a 100644
--- a/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/StatsActivity.java
+++ b/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/StatsActivity.java
@@ -4,12 +4,16 @@ import android.content.Context;
 import android.graphics.Color;
 import android.graphics.drawable.ColorDrawable;
 import android.os.Bundle;
-import android.support.design.widget.TabLayout;
-import android.support.v4.app.Fragment;
-import android.support.v4.app.FragmentManager;
-import android.support.v4.app.FragmentPagerAdapter;
-import android.support.v4.view.ViewPager;
-import android.support.v7.widget.Toolbar;
+import com.google.android.material.tabs.TabLayout;
+
+import androidx.core.content.ContextCompat;
+import androidx.fragment.app.Fragment;
+import androidx.fragment.app.FragmentManager;
+import androidx.fragment.app.FragmentPagerAdapter;
+import androidx.fragment.app.FragmentStatePagerAdapter;
+import androidx.viewpager.widget.PagerAdapter;
+import androidx.viewpager.widget.ViewPager;
+import androidx.appcompat.widget.Toolbar;
 import android.view.LayoutInflater;
 import android.view.Menu;
 import android.view.MenuItem;
@@ -30,12 +34,12 @@ import java.util.List;
 public class StatsActivity extends BaseActivity {
 
     /**
-     * The {@link android.support.v4.view.PagerAdapter} that will provide
+     * The {@link PagerAdapter} that will provide
      * fragments for each of the sections. We use a
      * {@link FragmentPagerAdapter} derivative, which will keep every
      * loaded fragment in memory. If this becomes too memory intensive, it
      * may be best to switch to a
-     * {@link android.support.v4.app.FragmentStatePagerAdapter}.
+     * {@link FragmentStatePagerAdapter}.
      */
     private SectionsPagerAdapter mSectionsPagerAdapter;
 
@@ -52,10 +56,10 @@ public class StatsActivity extends BaseActivity {
         Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
         setSupportActionBar(toolbar);
 
-        android.support.v7.app.ActionBar actionBar = getSupportActionBar();
+        androidx.appcompat.app.ActionBar actionBar = getSupportActionBar();
         actionBar.setTitle(R.string.menu_highscore);
         actionBar.setDisplayHomeAsUpEnabled(true);
-        actionBar.setBackgroundDrawable(new ColorDrawable(Color.parseColor("#024265")));
+        //actionBar.setBackgroundDrawable(new ColorDrawable(ContextCompat.getColor(this, R.color.colorPrimary)));
 
         // Create the adapter that will return a fragment for each of the three
         // primary sections of the activity.
diff --git a/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/TutorialActivity.java b/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/TutorialActivity.java
index 9516aea..20b16b6 100644
--- a/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/TutorialActivity.java
+++ b/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/TutorialActivity.java
@@ -5,9 +5,9 @@ import android.content.Intent;
 import android.graphics.Color;
 import android.os.Build;
 import android.os.Bundle;
-import android.support.v4.view.PagerAdapter;
-import android.support.v4.view.ViewPager;
-import android.support.v7.app.AppCompatActivity;
+import androidx.viewpager.widget.PagerAdapter;
+import androidx.viewpager.widget.ViewPager;
+import androidx.appcompat.app.AppCompatActivity;
 import android.text.Html;
 import android.view.LayoutInflater;
 import android.view.View;
diff --git a/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/view/SudokuButtonType.java b/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/view/SudokuButtonType.java
index ae27f9a..5fb3854 100644
--- a/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/view/SudokuButtonType.java
+++ b/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/view/SudokuButtonType.java
@@ -1,6 +1,6 @@
 package org.secuso.privacyfriendlysudoku.ui.view;
 
-import android.support.annotation.DrawableRes;
+import androidx.annotation.DrawableRes;
 
 import java.util.ArrayList;
 import java.util.List;
diff --git a/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/view/SudokuCellView.java b/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/view/SudokuCellView.java
index 6f7fa62..06b9a0a 100644
--- a/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/view/SudokuCellView.java
+++ b/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/view/SudokuCellView.java
@@ -53,6 +53,21 @@ public class SudokuCellView extends View {
         mRow = gameCell.getRow();
         mCol = gameCell.getCol();
         this.size = size;
+
+        initLayoutParams();
+    }
+
+    private void initLayoutParams() {
+        if(this.params == null) {
+            params = new RelativeLayout.LayoutParams(mWidth, mHeight);
+        }
+
+        // Set Layout
+        params.width = mWidth;
+        params.height = mHeight;
+        params.topMargin = mRow*mHeight;
+        params.leftMargin = mCol*mWidth;
+        this.setLayoutParams(params);
     }
 
     public void setSymbols(Symbol s) {
@@ -74,21 +89,17 @@ public class SudokuCellView extends View {
         return true;
     }*/
 
+    @Override
+    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
+        super.onLayout(changed, left, top, right, bottom);
+
+
+    }
+
     @Override
     public void onDraw(Canvas canvas) {
         super.onDraw(canvas);
 
-        if(this.params == null) {
-            params = new RelativeLayout.LayoutParams(mWidth, mHeight);
-        }
-
-        // Set Layout
-        params.width = mWidth;
-        params.height = mHeight;
-        params.topMargin = mRow*mHeight;
-        params.leftMargin = mCol*mWidth;
-        this.setLayoutParams(params);
-
         // Draw single Field
         drawInfo(canvas);
     }
diff --git a/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/view/SudokuFieldLayout.java b/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/view/SudokuFieldLayout.java
index a52e044..0a4fac8 100644
--- a/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/view/SudokuFieldLayout.java
+++ b/app/src/main/java/org/secuso/privacyfriendlysudoku/ui/view/SudokuFieldLayout.java
@@ -5,7 +5,6 @@ import android.content.SharedPreferences;
 import android.graphics.Canvas;
 import android.graphics.Color;
 import android.graphics.Paint;
-import android.support.v7.widget.RecyclerView;
 import android.util.AttributeSet;
 import android.view.MotionEvent;
 import android.view.View;
@@ -134,7 +133,6 @@ public class SudokuFieldLayout extends RelativeLayout implements IHighlightChang
     @Override
     protected void onLayout(boolean changed, int l, int t, int r, int b) {
         super.onLayout(changed,l,t,r,b);
-
         isWidthLimiting = r-l == Math.min(r-l, b-t);
 
         if(changed && gameController != null) {
diff --git a/app/src/main/res/drawable/ic_launcher_foreground.xml b/app/src/main/res/drawable/ic_launcher_foreground.xml
new file mode 100644
index 0000000..4457f4c
--- /dev/null
+++ b/app/src/main/res/drawable/ic_launcher_foreground.xml
@@ -0,0 +1,36 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="512dp"
+    android:height="512dp"
+    android:viewportWidth="512"
+    android:viewportHeight="512">
+  <path
+      android:pathData="M174.65,41.63h13.43v429.87h-13.43z"
+      android:fillColor="#fff"/>
+  <path
+      android:pathData="M322.42,41.63h13.43v429.87h-13.43z"
+      android:fillColor="#fff"/>
+  <path
+      android:pathData="M40.31,337.17l0,-13.43l429.87,-0l0,13.43z"
+      android:fillColor="#fff"/>
+  <path
+      android:pathData="M40.31,189.4l0,-13.43l429.87,-0l0,13.43z"
+      android:fillColor="#fff"/>
+  <path
+      android:pathData="M94.05,68.49h40.3V55.06H94.05a26.87,26.87 0,0 0,0 53.73h13.43a13.44,13.44 0,1 1,0 26.87H67.18v13.43h40.3a26.87,26.87 0,0 0,0 -53.73H94.05a13.44,13.44 0,0 1,0 -26.87Z"
+      android:fillColor="#fff"/>
+  <path
+      android:pathData="M262,206.19h-40.3v94L262,300.19a26.86,26.86 0,0 0,26.86 -26.87v-40.3A26.86,26.86 0,0 0,262 206.19ZM262,286.79L235.1,286.79L235.1,219.62L262,219.62a13.43,13.43 0,0 1,13.43 13.43v40.3A13.43,13.43 0,0 1,262 286.79Z"
+      android:fillColor="#fff"/>
+  <path
+      android:pathData="M406.38,206.19L392.94,206.19a26.86,26.86 0,0 0,-26.86 26.86v40.3a26.86,26.86 0,0 0,26.86 26.87h13.44a26.87,26.87 0,0 0,26.86 -26.87v-40.3A26.87,26.87 0,0 0,406.38 206.19ZM419.81,273.35a13.48,13.48 0,0 1,-13.43 13.44L392.94,286.79a13.47,13.47 0,0 1,-13.43 -13.44v-40.3a13.47,13.47 0,0 1,13.43 -13.43h13.44a13.48,13.48 0,0 1,13.43 13.43Z"
+      android:fillColor="#fff"/>
+  <path
+      android:pathData="M134.35,374.01l0,0l0,0l0,0l0,-9.5l-9.36,0l-0.04,0.1l-0.1,-0.1l-37.91,37.91l-6.32,6.32l0,-12.56l0,-31.67l-13.44,0l0,19.82l0,17.34l0,20.51l0,17.64l0,18.72l13.44,0l0,-30.8l6.45,-6.45l37.78,37.25l0,0l9.5,0l0,-9.36l-37.85,-37.33l37.84,-37.84l0.01,0z"
+      android:fillColor="#fff"/>
+  <path
+      android:pathData="M275.4,58.42v60.45a20.15,20.15 0,1 1,-40.3 0V58.42H221.67v60.45a33.58,33.58 0,1 0,67.16 0V58.42Z"
+      android:fillColor="#fff"/>
+  <path
+      android:pathData="M275.4,364.51V425a20.15,20.15 0,1 1,-40.3 0V364.51H221.67V425a33.58,33.58 0,1 0,67.16 0V364.51Z"
+      android:fillColor="#fff"/>
+</vector>
diff --git a/app/src/main/res/drawable/ic_launcher_foreground_shadow.xml b/app/src/main/res/drawable/ic_launcher_foreground_shadow.xml
new file mode 100644
index 0000000..4a5b108
--- /dev/null
+++ b/app/src/main/res/drawable/ic_launcher_foreground_shadow.xml
@@ -0,0 +1,57 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:aapt="http://schemas.android.com/aapt"
+    android:width="512dp"
+    android:height="512dp"
+    android:viewportWidth="512"
+    android:viewportHeight="512">
+  <path
+      android:pathData="M510.91,471.7V216.47L336.27,41.83H323.68V93.05L289.26,58.62H275.82v40.3l-40.3,-40.3H222.09l0,16.77L188.51,41.83H175.07l0.12,54.69L134.35,55.68 88.6,62 71.8,76.25l2.52,17.64 5,6.71 -5.88,-0.84 38.62,38.62 -44.49,-2.52V149.3l27,27 -53.83,-0.1V189.6L174.23,323.09H40.74v14.28l26.87,26.86v94L121.34,512H470.61A40.42,40.42 0,0 0,510.91 471.7Z">
+    <aapt:attr name="android:fillColor">
+      <gradient 
+          android:startY="43.94"
+          android:startX="119.85"
+          android:endY="551.52"
+          android:endX="412.9"
+          android:type="linear">
+        <item android:offset="0" android:color="#FF004492"/>
+        <item android:offset="0.22" android:color="#F9004593"/>
+        <item android:offset="0.39" android:color="#E8024894"/>
+        <item android:offset="0.55" android:color="#C9044E97"/>
+        <item android:offset="0.7" android:color="#A007569B"/>
+        <item android:offset="0.84" android:color="#6B0A60A0"/>
+        <item android:offset="0.97" android:color="#280F6CA6"/>
+        <item android:offset="1" android:color="#19106FA8"/>
+      </gradient>
+    </aapt:attr>
+  </path>
+  <path
+      android:pathData="M174.65,41.63h13.43v429.87h-13.43z"
+      android:fillColor="#fff"/>
+  <path
+      android:pathData="M322.42,41.63h13.43v429.87h-13.43z"
+      android:fillColor="#fff"/>
+  <path
+      android:pathData="M40.31,337.17l0,-13.43l429.87,-0l0,13.43z"
+      android:fillColor="#fff"/>
+  <path
+      android:pathData="M40.31,189.4l0,-13.43l429.87,-0l0,13.43z"
+      android:fillColor="#fff"/>
+  <path
+      android:pathData="M94.05,68.49h40.3V55.06H94.05a26.87,26.87 0,0 0,0 53.73h13.43a13.44,13.44 0,1 1,0 26.87H67.18v13.43h40.3a26.87,26.87 0,0 0,0 -53.73H94.05a13.44,13.44 0,0 1,0 -26.87Z"
+      android:fillColor="#fff"/>
+  <path
+      android:pathData="M262,206.19h-40.3v94L262,300.19a26.86,26.86 0,0 0,26.86 -26.87v-40.3A26.86,26.86 0,0 0,262 206.19ZM262,286.79L235.1,286.79L235.1,219.62L262,219.62a13.43,13.43 0,0 1,13.43 13.43v40.3A13.43,13.43 0,0 1,262 286.79Z"
+      android:fillColor="#fff"/>
+  <path
+      android:pathData="M406.38,206.19L392.94,206.19a26.86,26.86 0,0 0,-26.86 26.86v40.3a26.86,26.86 0,0 0,26.86 26.87h13.44a26.87,26.87 0,0 0,26.86 -26.87v-40.3A26.87,26.87 0,0 0,406.38 206.19ZM419.81,273.35a13.48,13.48 0,0 1,-13.43 13.44L392.94,286.79a13.47,13.47 0,0 1,-13.43 -13.44v-40.3a13.47,13.47 0,0 1,13.43 -13.43h13.44a13.48,13.48 0,0 1,13.43 13.43Z"
+      android:fillColor="#fff"/>
+  <path
+      android:pathData="M134.35,374.01l0,0l0,0l0,0l0,-9.5l-9.36,0l-0.04,0.1l-0.1,-0.1l-37.91,37.91l-6.32,6.32l0,-12.56l0,-31.67l-13.44,0l0,19.82l0,17.34l0,20.51l0,17.64l0,18.72l13.44,0l0,-30.8l6.45,-6.45l37.78,37.25l0,0l9.5,0l0,-9.36l-37.85,-37.33l37.84,-37.84l0.01,0z"
+      android:fillColor="#fff"/>
+  <path
+      android:pathData="M275.4,58.42v60.45a20.15,20.15 0,1 1,-40.3 0V58.42H221.67v60.45a33.58,33.58 0,1 0,67.16 0V58.42Z"
+      android:fillColor="#fff"/>
+  <path
+      android:pathData="M275.4,364.51V425a20.15,20.15 0,1 1,-40.3 0V364.51H221.67V425a33.58,33.58 0,1 0,67.16 0V364.51Z"
+      android:fillColor="#fff"/>
+</vector>
diff --git a/app/src/main/res/layout-land/activity_main_menu.xml b/app/src/main/res/layout-land/activity_main_menu.xml
index 34926fe..bc24413 100644
--- a/app/src/main/res/layout-land/activity_main_menu.xml
+++ b/app/src/main/res/layout-land/activity_main_menu.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<android.support.v4.widget.DrawerLayout android:id="@+id/drawer_layout_main"
+<androidx.drawerlayout.widget.DrawerLayout android:id="@+id/drawer_layout_main"
     android:layout_height="match_parent"
     android:layout_width="match_parent"
     android:fitsSystemWindows="true"
@@ -8,7 +8,7 @@
     xmlns:tools="http://schemas.android.com/tools"
     xmlns:app="http://schemas.android.com/apk/res-auto">
 
-<android.support.design.widget.CoordinatorLayout
+<androidx.coordinatorlayout.widget.CoordinatorLayout
     xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
     xmlns:app="http://schemas.android.com/apk/res-auto"
@@ -17,23 +17,23 @@
     android:layout_height="match_parent"
     android:layout_width="match_parent">
 
-    <android.support.design.widget.AppBarLayout
+    <com.google.android.material.appbar.AppBarLayout
         android:id="@+id/appbar"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:theme="@style/AppTheme.AppBarOverlay">
 
-        <android.support.v7.widget.Toolbar
+        <androidx.appcompat.widget.Toolbar
              android:id="@+id/toolbar"
              android:layout_width="match_parent"
              android:layout_height="?attr/actionBarSize"
              android:background="?attr/colorPrimary"
              app:popupTheme="@style/AppTheme.PopupOverlay">
 
-        </android.support.v7.widget.Toolbar>
+        </androidx.appcompat.widget.Toolbar>
 
 
-    </android.support.design.widget.AppBarLayout>
+    </com.google.android.material.appbar.AppBarLayout>
 
         <LinearLayout
             android:layout_width="match_parent"
@@ -49,7 +49,7 @@
                 android:layoutDirection="ltr"
                 android:layout_weight="1">
 
-                <android.support.v4.view.ViewPager
+                <androidx.viewpager.widget.ViewPager
                     android:id="@+id/scroller"
                     android:layout_width="match_parent"
                     android:layout_height="match_parent"
@@ -59,7 +59,7 @@
                     android:id="@+id/arrow_left"
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
-                    android:src="@drawable/ic_keyboard_arrow_left_black_24dp"
+                    app:srcCompat="@drawable/ic_keyboard_arrow_left_black_24dp"
                     android:layout_alignParentLeft="true"
                     android:layout_alignParentStart="true"
                     android:padding="@dimen/activity_horizontal_margin"
@@ -72,7 +72,7 @@
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
                     android:padding="@dimen/activity_horizontal_margin"
-                    android:src="@drawable/ic_keyboard_arrow_right_black_24dp"
+                    app:srcCompat="@drawable/ic_keyboard_arrow_right_black_24dp"
                     android:layout_alignParentRight="true"
                     android:layout_alignParentEnd="true"
                     android:layout_marginEnd="@dimen/activity_horizontal_margin"
@@ -157,8 +157,8 @@
 
    </LinearLayout>
 
-</android.support.design.widget.CoordinatorLayout>
-    <android.support.design.widget.NavigationView
+</androidx.coordinatorlayout.widget.CoordinatorLayout>
+    <com.google.android.material.navigation.NavigationView
         android:id="@+id/nav_view_main"
         android:layout_width="wrap_content"
         android:layout_height="match_parent"
@@ -168,4 +168,4 @@
         app:menu="@menu/menu_drawer_main"
         app:headerLayout="@layout/nav_header" />
 
-</android.support.v4.widget.DrawerLayout>
\ No newline at end of file
+</androidx.drawerlayout.widget.DrawerLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout-small/activity_main_menu.xml b/app/src/main/res/layout-small/activity_main_menu.xml
index 63f98e8..d989504 100644
--- a/app/src/main/res/layout-small/activity_main_menu.xml
+++ b/app/src/main/res/layout-small/activity_main_menu.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<android.support.v4.widget.DrawerLayout android:id="@+id/drawer_layout_main"
+<androidx.drawerlayout.widget.DrawerLayout android:id="@+id/drawer_layout_main"
     android:layout_height="match_parent"
     android:layout_width="match_parent"
     android:fitsSystemWindows="true"
@@ -8,7 +8,7 @@
     xmlns:tools="http://schemas.android.com/tools"
     xmlns:app="http://schemas.android.com/apk/res-auto">
 
-<android.support.design.widget.CoordinatorLayout
+<androidx.coordinatorlayout.widget.CoordinatorLayout
     xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
     xmlns:app="http://schemas.android.com/apk/res-auto"
@@ -17,23 +17,23 @@
     android:layout_height="match_parent"
     android:layout_width="match_parent">
 
-    <android.support.design.widget.AppBarLayout
+    <com.google.android.material.appbar.AppBarLayout
         android:id="@+id/appbar"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:theme="@style/AppTheme.AppBarOverlay">
 
-        <android.support.v7.widget.Toolbar
+        <androidx.appcompat.widget.Toolbar
              android:id="@+id/toolbar"
              android:layout_width="match_parent"
              android:layout_height="?attr/actionBarSize"
              android:background="?attr/colorPrimary"
              app:popupTheme="@style/AppTheme.PopupOverlay">
 
-        </android.support.v7.widget.Toolbar>
+        </androidx.appcompat.widget.Toolbar>
 
 
-    </android.support.design.widget.AppBarLayout>
+    </com.google.android.material.appbar.AppBarLayout>
 
    <LinearLayout
         android:layout_height="match_parent"
@@ -49,7 +49,7 @@
             android:layoutDirection="ltr"
             android:layout_weight="4">
 
-        <android.support.v4.view.ViewPager
+        <androidx.viewpager.widget.ViewPager
             android:id="@+id/scroller"
 
             android:layout_width="match_parent"
@@ -60,7 +60,7 @@
                 android:id="@+id/arrow_left"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
-                android:src="@drawable/ic_keyboard_arrow_left_black_24dp"
+                app:srcCompat="@drawable/ic_keyboard_arrow_left_black_24dp"
                 android:layout_alignParentLeft="true"
                 android:layout_alignParentStart="true"
                 android:padding="@dimen/activity_horizontal_margin"
@@ -72,7 +72,7 @@
                 android:id="@+id/arrow_right"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
-                android:src="@drawable/ic_keyboard_arrow_right_black_24dp"
+                app:srcCompat="@drawable/ic_keyboard_arrow_right_black_24dp"
                 android:layout_alignParentRight="true"
                 android:layout_alignParentEnd="true"
                 android:padding="@dimen/activity_horizontal_margin"
@@ -229,9 +229,9 @@
 
    </LinearLayout>
 
-</android.support.design.widget.CoordinatorLayout>
+</androidx.coordinatorlayout.widget.CoordinatorLayout>
 
-    <android.support.design.widget.NavigationView
+    <com.google.android.material.navigation.NavigationView
         android:id="@+id/nav_view_main"
         android:layout_width="wrap_content"
         android:layout_height="match_parent"
@@ -241,4 +241,4 @@
         app:menu="@menu/menu_drawer_main"
         app:headerLayout="@layout/nav_header" />
 
-    </android.support.v4.widget.DrawerLayout>
\ No newline at end of file
+    </androidx.drawerlayout.widget.DrawerLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout-xlarge/activity_main_menu.xml b/app/src/main/res/layout-xlarge/activity_main_menu.xml
index cb60e93..1f21a39 100644
--- a/app/src/main/res/layout-xlarge/activity_main_menu.xml
+++ b/app/src/main/res/layout-xlarge/activity_main_menu.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<android.support.v4.widget.DrawerLayout android:id="@+id/drawer_layout_main"
+<androidx.drawerlayout.widget.DrawerLayout android:id="@+id/drawer_layout_main"
     android:layout_height="match_parent"
     android:layout_width="match_parent"
     android:fitsSystemWindows="true"
@@ -8,7 +8,7 @@
     xmlns:tools="http://schemas.android.com/tools"
     xmlns:app="http://schemas.android.com/apk/res-auto">
 
-<android.support.design.widget.CoordinatorLayout
+<androidx.coordinatorlayout.widget.CoordinatorLayout
     xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
     xmlns:app="http://schemas.android.com/apk/res-auto"
@@ -17,23 +17,23 @@
     android:layout_height="match_parent"
     android:layout_width="match_parent">
 
-    <android.support.design.widget.AppBarLayout
+    <com.google.android.material.appbar.AppBarLayout
         android:id="@+id/appbar"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:theme="@style/AppTheme.AppBarOverlay">
 
-        <android.support.v7.widget.Toolbar
+        <androidx.appcompat.widget.Toolbar
              android:id="@+id/toolbar"
              android:layout_width="match_parent"
              android:layout_height="?attr/actionBarSize"
              android:background="?attr/colorPrimary"
              app:popupTheme="@style/AppTheme.PopupOverlay">
 
-        </android.support.v7.widget.Toolbar>
+        </androidx.appcompat.widget.Toolbar>
 
 
-    </android.support.design.widget.AppBarLayout>
+    </com.google.android.material.appbar.AppBarLayout>
 
    <LinearLayout
         android:layout_height="match_parent"
@@ -49,7 +49,7 @@
             android:layoutDirection="ltr"
             android:layout_weight="4">
 
-        <android.support.v4.view.ViewPager
+        <androidx.viewpager.widget.ViewPager
             android:id="@+id/scroller"
 
             android:layout_width="match_parent"
@@ -60,7 +60,7 @@
                 android:id="@+id/arrow_left"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
-                android:src="@drawable/ic_keyboard_arrow_left_black_24dp"
+                app:srcCompat="@drawable/ic_keyboard_arrow_left_black_24dp"
                 android:layout_alignParentLeft="true"
                 android:layout_alignParentStart="true"
                 android:padding="@dimen/activity_horizontal_margin"
@@ -72,7 +72,7 @@
                 android:id="@+id/arrow_right"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
-                android:src="@drawable/ic_keyboard_arrow_right_black_24dp"
+                app:srcCompat="@drawable/ic_keyboard_arrow_right_black_24dp"
                 android:layout_alignParentRight="true"
                 android:layout_alignParentEnd="true"
                 android:padding="@dimen/activity_horizontal_margin"
@@ -227,9 +227,9 @@
 
    </LinearLayout>
 
-</android.support.design.widget.CoordinatorLayout>
+</androidx.coordinatorlayout.widget.CoordinatorLayout>
 
-    <android.support.design.widget.NavigationView
+    <com.google.android.material.navigation.NavigationView
         android:id="@+id/nav_view_main"
         android:layout_width="wrap_content"
         android:layout_height="match_parent"
@@ -239,4 +239,4 @@
         app:menu="@menu/menu_drawer_main"
         app:headerLayout="@layout/nav_header" />
 
-</android.support.v4.widget.DrawerLayout>
\ No newline at end of file
+</androidx.drawerlayout.widget.DrawerLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/activity_game_view.xml b/app/src/main/res/layout/activity_game_view.xml
index 25f58e3..a7c23f5 100644
--- a/app/src/main/res/layout/activity_game_view.xml
+++ b/app/src/main/res/layout/activity_game_view.xml
@@ -1,29 +1,25 @@
 <?xml version="1.0" encoding="utf-8"?>
-<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
+<androidx.drawerlayout.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
     xmlns:tools="http://schemas.android.com/tools"
     android:id="@+id/drawer_layout"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:fitsSystemWindows="true">
-    <!-- tools:openDrawer="start" -->
 
-<android.support.design.widget.CoordinatorLayout
-    xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:app="http://schemas.android.com/apk/res-auto"
-    xmlns:tools="http://schemas.android.com/tools"
+<androidx.coordinatorlayout.widget.CoordinatorLayout
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:fitsSystemWindows="true"
     tools:context="tu_darmstadt.sudoku.activity.GameActivity">
 
-    <android.support.design.widget.AppBarLayout
+    <com.google.android.material.appbar.AppBarLayout
         android:layout_height="wrap_content"
         android:layout_width="match_parent"
         android:clipChildren="false"
         android:theme="@style/AppTheme.AppBarOverlay">
 
-        <android.support.v7.widget.Toolbar android:id="@+id/toolbar"
+        <androidx.appcompat.widget.Toolbar android:id="@+id/toolbar"
             android:layout_width="match_parent"
             android:layout_height="?attr/actionBarSize"
             android:background="?attr/colorPrimary"
@@ -76,15 +72,15 @@
                     android:id="@+id/timerView"
                     android:gravity="end"/>
             </LinearLayout>
-        </android.support.v7.widget.Toolbar>
+        </androidx.appcompat.widget.Toolbar>
 
-    </android.support.design.widget.AppBarLayout>
+    </com.google.android.material.appbar.AppBarLayout>
 
     <include layout="@layout/content_game_view" />
 
-</android.support.design.widget.CoordinatorLayout>
+</androidx.coordinatorlayout.widget.CoordinatorLayout>
 
-    <android.support.design.widget.NavigationView
+    <com.google.android.material.navigation.NavigationView
         android:id="@+id/nav_view"
         android:layout_width="wrap_content"
         android:fitsSystemWindows="true"
@@ -94,4 +90,4 @@
         app:menu="@menu/menu_drawer"
         app:headerLayout="@layout/nav_header" />
 
-</android.support.v4.widget.DrawerLayout>
\ No newline at end of file
+</androidx.drawerlayout.widget.DrawerLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/activity_main_menu.xml b/app/src/main/res/layout/activity_main_menu.xml
index dc332c2..8c6299b 100644
--- a/app/src/main/res/layout/activity_main_menu.xml
+++ b/app/src/main/res/layout/activity_main_menu.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<android.support.v4.widget.DrawerLayout android:id="@+id/drawer_layout_main"
+<androidx.drawerlayout.widget.DrawerLayout android:id="@+id/drawer_layout_main"
     android:layout_height="match_parent"
     android:layout_width="match_parent"
     android:fitsSystemWindows="true"
@@ -8,30 +8,30 @@
     xmlns:tools="http://schemas.android.com/tools"
     xmlns:app="http://schemas.android.com/apk/res-auto">
 
-<android.support.design.widget.CoordinatorLayout
+<androidx.coordinatorlayout.widget.CoordinatorLayout
     xmlns:app="http://schemas.android.com/apk/res-auto"
     android:fitsSystemWindows="true"
     tools:context="tu_darmstadt.sudoku.ui.MainActivity"
     android:layout_height="match_parent"
     android:layout_width="match_parent">
 
-    <android.support.design.widget.AppBarLayout
+    <com.google.android.material.appbar.AppBarLayout
         android:id="@+id/appbar"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:theme="@style/AppTheme.AppBarOverlay">
 
-        <android.support.v7.widget.Toolbar
+        <androidx.appcompat.widget.Toolbar
              android:id="@+id/toolbar"
              android:layout_width="match_parent"
              android:layout_height="?attr/actionBarSize"
              android:background="?attr/colorPrimary"
              app:popupTheme="@style/AppTheme.PopupOverlay">
 
-        </android.support.v7.widget.Toolbar>
+        </androidx.appcompat.widget.Toolbar>
 
 
-    </android.support.design.widget.AppBarLayout>
+    </com.google.android.material.appbar.AppBarLayout>
 
    <LinearLayout
         android:layout_height="match_parent"
@@ -48,7 +48,7 @@
             android:layoutDirection="ltr"
             android:layout_weight="4">
 
-        <android.support.v4.view.ViewPager
+        <androidx.viewpager.widget.ViewPager
             android:id="@+id/scroller"
 
             android:layout_width="match_parent"
@@ -59,7 +59,7 @@
                 android:id="@+id/arrow_left"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
-                android:src="@drawable/ic_keyboard_arrow_left_black_24dp"
+                app:srcCompat="@drawable/ic_keyboard_arrow_left_black_24dp"
                 android:layout_alignParentLeft="true"
                 android:layout_alignParentStart="true"
                 android:padding="@dimen/activity_horizontal_margin"
@@ -71,7 +71,7 @@
                 android:id="@+id/arrow_right"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
-                android:src="@drawable/ic_keyboard_arrow_right_black_24dp"
+                app:srcCompat="@drawable/ic_keyboard_arrow_right_black_24dp"
                 android:layout_alignParentRight="true"
                 android:layout_alignParentEnd="true"
                 android:padding="@dimen/activity_horizontal_margin"
@@ -224,9 +224,9 @@
 
    </LinearLayout>
 
-</android.support.design.widget.CoordinatorLayout>
+</androidx.coordinatorlayout.widget.CoordinatorLayout>
 
-    <android.support.design.widget.NavigationView
+    <com.google.android.material.navigation.NavigationView
         android:id="@+id/nav_view_main"
         android:layout_width="wrap_content"
         android:layout_height="match_parent"
@@ -236,4 +236,4 @@
         app:menu="@menu/menu_drawer_main"
         app:headerLayout="@layout/nav_header" />
 
-</android.support.v4.widget.DrawerLayout>
+</androidx.drawerlayout.widget.DrawerLayout>
diff --git a/app/src/main/res/layout/activity_stats.xml b/app/src/main/res/layout/activity_stats.xml
index bb5ca10..a0bbb0a 100644
--- a/app/src/main/res/layout/activity_stats.xml
+++ b/app/src/main/res/layout/activity_stats.xml
@@ -1,30 +1,43 @@
 <?xml version="1.0" encoding="utf-8"?>
-<android.support.design.widget.CoordinatorLayout
+<androidx.coordinatorlayout.widget.CoordinatorLayout
     xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
     xmlns:app="http://schemas.android.com/apk/res-auto"
-    android:layout_width="match_parent" android:layout_height="match_parent"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    app:statusBarBackground="?attr/colorPrimary"
     android:fitsSystemWindows="true">
 
-    <android.support.design.widget.AppBarLayout android:id="@+id/appbar"
-        android:layout_width="match_parent" android:layout_height="wrap_content"
+    <com.google.android.material.appbar.AppBarLayout
+        android:id="@+id/appbar"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:clipChildren="false"
         android:theme="@style/AppTheme.AppBarOverlay">
 
-        <android.support.v7.widget.Toolbar android:id="@+id/toolbar"
-            android:layout_width="match_parent" android:layout_height="?attr/actionBarSize"
-            android:background="?attr/colorPrimary" app:popupTheme="@style/AppTheme.PopupOverlay"
+        <androidx.appcompat.widget.Toolbar
+            android:id="@+id/toolbar"
+            android:layout_width="match_parent"
+            android:layout_height="?attr/actionBarSize"
+            android:background="?attr/colorPrimary"
+            app:popupTheme="@style/AppTheme.PopupOverlay"
+            android:clipChildren="false"
             app:layout_scrollFlags="enterAlways">
 
-        </android.support.v7.widget.Toolbar>
+        </androidx.appcompat.widget.Toolbar>
 
-        <android.support.design.widget.TabLayout android:id="@+id/tabs"
-            android:layout_width="match_parent" android:layout_height="wrap_content" />
+        <com.google.android.material.tabs.TabLayout
+            android:id="@+id/tabs"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content" />
 
-    </android.support.design.widget.AppBarLayout>
+    </com.google.android.material.appbar.AppBarLayout>
 
-    <android.support.v4.view.ViewPager android:id="@+id/main_content"
-        android:layout_width="fill_parent" android:layout_height="fill_parent"
+    <androidx.viewpager.widget.ViewPager
+        android:id="@+id/main_content"
+        android:layout_width="fill_parent"
+        android:layout_height="fill_parent"
         app:layout_behavior="@string/appbar_scrolling_view_behavior" />
 
 
-</android.support.design.widget.CoordinatorLayout>
+</androidx.coordinatorlayout.widget.CoordinatorLayout>
diff --git a/app/src/main/res/layout/activity_tutorial.xml b/app/src/main/res/layout/activity_tutorial.xml
index 78a7d05..51a6287 100644
--- a/app/src/main/res/layout/activity_tutorial.xml
+++ b/app/src/main/res/layout/activity_tutorial.xml
@@ -7,7 +7,7 @@
     tools:showIn="@layout/activity_tutorial">
 
 
-    <android.support.v4.view.ViewPager
+    <androidx.viewpager.widget.ViewPager
         android:id="@+id/view_pager"
         android:layout_width="match_parent"
         android:layout_height="match_parent" />
diff --git a/app/src/main/res/layout/nav_header.xml b/app/src/main/res/layout/nav_header.xml
index 7d6b302..f4105c1 100644
--- a/app/src/main/res/layout/nav_header.xml
+++ b/app/src/main/res/layout/nav_header.xml
@@ -23,7 +23,7 @@
         android:contentDescription="App Logo"
         android:paddingEnd="@dimen/activity_horizontal_margin"
         android:paddingStart="@dimen/activity_horizontal_margin"
-        android:src="@mipmap/ic_launcher_nopfa"/>
+        android:src="@mipmap/ic_drawer"/>
 
     <TextView
         android:layout_width="wrap_content"
@@ -35,7 +35,5 @@
         android:layout_centerVertical="true"
         android:layout_toRightOf="@+id/imageView"
         android:layout_toEndOf="@+id/imageView"/>
-
 </RelativeLayout>
-
 </LinearLayout>
diff --git a/app/src/main/res/mipmap-anydpi-v26/ic_launcher.xml b/app/src/main/res/mipmap-anydpi-v26/ic_launcher.xml
new file mode 100644
index 0000000..bb326ba
--- /dev/null
+++ b/app/src/main/res/mipmap-anydpi-v26/ic_launcher.xml
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@color/ic_launcher_background"/>
+    <foreground>
+        <inset android:drawable="@drawable/ic_launcher_foreground_shadow"
+            android:inset="21%"/>
+    </foreground>
+</adaptive-icon>
\ No newline at end of file
diff --git a/app/src/main/res/mipmap-hdpi/ic_launcher_nopfa.png b/app/src/main/res/mipmap-hdpi/ic_drawer.png
similarity index 100%
rename from app/src/main/res/mipmap-hdpi/ic_launcher_nopfa.png
rename to app/src/main/res/mipmap-hdpi/ic_drawer.png
diff --git a/app/src/main/res/mipmap-hdpi/ic_launcher.png b/app/src/main/res/mipmap-hdpi/ic_launcher.png
index 8232e9b..7d45a25 100644
Binary files a/app/src/main/res/mipmap-hdpi/ic_launcher.png and b/app/src/main/res/mipmap-hdpi/ic_launcher.png differ
diff --git a/app/src/main/res/mipmap-ldpi/ic_launcher_nopfa.png b/app/src/main/res/mipmap-ldpi/ic_drawer.png
similarity index 100%
rename from app/src/main/res/mipmap-ldpi/ic_launcher_nopfa.png
rename to app/src/main/res/mipmap-ldpi/ic_drawer.png
diff --git a/app/src/main/res/mipmap-ldpi/ic_launcher.png b/app/src/main/res/mipmap-ldpi/ic_launcher.png
new file mode 100644
index 0000000..d0d4ef6
Binary files /dev/null and b/app/src/main/res/mipmap-ldpi/ic_launcher.png differ
diff --git a/app/src/main/res/mipmap-mdpi/ic_launcher_nopfa.png b/app/src/main/res/mipmap-mdpi/ic_drawer.png
similarity index 100%
rename from app/src/main/res/mipmap-mdpi/ic_launcher_nopfa.png
rename to app/src/main/res/mipmap-mdpi/ic_drawer.png
diff --git a/app/src/main/res/mipmap-mdpi/ic_launcher.png b/app/src/main/res/mipmap-mdpi/ic_launcher.png
index b1ee90f..67f7df5 100644
Binary files a/app/src/main/res/mipmap-mdpi/ic_launcher.png and b/app/src/main/res/mipmap-mdpi/ic_launcher.png differ
diff --git a/app/src/main/res/mipmap-xhdpi/ic_launcher_nopfa.png b/app/src/main/res/mipmap-xhdpi/ic_drawer.png
similarity index 100%
rename from app/src/main/res/mipmap-xhdpi/ic_launcher_nopfa.png
rename to app/src/main/res/mipmap-xhdpi/ic_drawer.png
diff --git a/app/src/main/res/mipmap-xhdpi/ic_launcher.png b/app/src/main/res/mipmap-xhdpi/ic_launcher.png
index f22ff3c..96dfb02 100644
Binary files a/app/src/main/res/mipmap-xhdpi/ic_launcher.png and b/app/src/main/res/mipmap-xhdpi/ic_launcher.png differ
diff --git a/app/src/main/res/mipmap-xxhdpi/ic_launcher_nopfa.png b/app/src/main/res/mipmap-xxhdpi/ic_drawer.png
similarity index 100%
rename from app/src/main/res/mipmap-xxhdpi/ic_launcher_nopfa.png
rename to app/src/main/res/mipmap-xxhdpi/ic_drawer.png
diff --git a/app/src/main/res/mipmap-xxhdpi/ic_launcher.png b/app/src/main/res/mipmap-xxhdpi/ic_launcher.png
index 70f4941..b26abd4 100644
Binary files a/app/src/main/res/mipmap-xxhdpi/ic_launcher.png and b/app/src/main/res/mipmap-xxhdpi/ic_launcher.png differ
diff --git a/app/src/main/res/mipmap-xxxhdpi/ic_launcher_nopfa.png b/app/src/main/res/mipmap-xxxhdpi/ic_drawer.png
similarity index 100%
rename from app/src/main/res/mipmap-xxxhdpi/ic_launcher_nopfa.png
rename to app/src/main/res/mipmap-xxxhdpi/ic_drawer.png
diff --git a/app/src/main/res/mipmap-xxxhdpi/ic_launcher.png b/app/src/main/res/mipmap-xxxhdpi/ic_launcher.png
index 2ebc86d..0b52777 100644
Binary files a/app/src/main/res/mipmap-xxxhdpi/ic_launcher.png and b/app/src/main/res/mipmap-xxxhdpi/ic_launcher.png differ
diff --git a/app/src/main/res/values/colors.xml b/app/src/main/res/values/colors.xml
index 4f3641a..3ab7520 100644
--- a/app/src/main/res/values/colors.xml
+++ b/app/src/main/res/values/colors.xml
@@ -28,4 +28,6 @@
         <item>@color/dot_dark_screen</item>
         <item>@color/dot_dark_screen</item>
     </array>
+
+    <color name="ic_launcher_background">#3680BB</color>
 </resources>
diff --git a/build.gradle b/build.gradle
index c068560..db1fb47 100644
--- a/build.gradle
+++ b/build.gradle
@@ -6,7 +6,7 @@ buildscript {
         google()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:3.0.1'
+        classpath 'com.android.tools.build:gradle:3.6.2'
 
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files
@@ -16,6 +16,7 @@ buildscript {
 allprojects {
     repositories {
         jcenter()
+        google()
     }
 }
 
diff --git a/gradle.properties b/gradle.properties
index 1d3591c..915f0e6 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -15,4 +15,6 @@
 # When configured, Gradle will run in incubating parallel mode.
 # This option should only be used with decoupled projects. More details, visit
 # http://www.gradle.org/docs/current/userguide/multi_project_builds.html#sec:decoupled_projects
-# org.gradle.parallel=true
\ No newline at end of file
+# org.gradle.parallel=true
+android.enableJetifier=true
+android.useAndroidX=true
\ No newline at end of file
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index 9dfcc65..44bb974 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,6 +1,6 @@
-#Fri Jan 19 17:45:21 CET 2018
+#Wed Oct 23 12:21:08 CEST 2019
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.1-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-5.6.4-all.zip