diff --git a/app/build.gradle b/app/build.gradle
index ee7e88a1..49066e52 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -17,16 +17,15 @@
 apply plugin: 'com.android.application'
 apply plugin: 'kotlin-android'
 
-
 android {
     compileSdkVersion 28
-    buildToolsVersion '28.0.3'
+    buildToolsVersion "29.0.3"
 
     signingConfigs {
         release {
-            def keystore = file('keystore.properties');
+            def keystore = file('keystore.properties')
             if (keystore.exists()) {
-                def Properties keyProps = new Properties()
+                Properties keyProps = new Properties()
                 keyProps.load(new FileInputStream(keystore))
                 storeFile file(keyProps["store"])
                 storePassword keyProps["storePass"]
@@ -44,18 +43,15 @@ android {
         versionName '5.6'
     }
 
-
     buildTypes {
         release {
             minifyEnabled false
-            shrinkResources false
-            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'
+            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
             signingConfig signingConfigs.release
         }
     }
 
     flavorDimensions "distribution"
-
     productFlavors {
         base {
             // Basic build
@@ -67,29 +63,52 @@ android {
             dimension "distribution"
         }
     }
+
+    compileOptions {
+        encoding "UTF-8"
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+
+    kotlinOptions {
+        jvmTarget = JavaVersion.VERSION_1_8.toString()
+    }
 }
 
 dependencies {
-    implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
-    implementation 'androidx.appcompat:appcompat:1.0.2'
-    implementation 'androidx.recyclerview:recyclerview:1.0.0'
-    implementation 'com.google.android.material:material:1.0.0'
+// Kotlin
+    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin_version"
+
+// Android Support
+    implementation 'androidx.appcompat:appcompat:1.2.0'
     implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
-    implementation 'com.squareup.retrofit2:retrofit:2.3.0'
-    implementation ('com.squareup.retrofit2:converter-simplexml:2.3.0') {
+    implementation 'androidx.recyclerview:recyclerview:1.1.0'
+    implementation 'com.google.android.material:material:1.2.1'
+
+// Third-party
+    // Retrofit
+    implementation 'com.squareup.retrofit2:retrofit:2.6.4'
+    implementation 'com.squareup.retrofit2:adapter-rxjava2:2.6.4'
+    implementation('com.squareup.retrofit2:converter-simplexml:2.6.4') {
         exclude module: 'xpp3'
         exclude module: 'stax-api'
     }
-    implementation 'com.squareup.retrofit2:adapter-rxjava:2.3.0'
-    implementation 'com.google.code.gson:gson:2.8.0'
-    implementation 'io.reactivex:rxandroid:1.2.1'
-    implementation 'io.reactivex:rxjava:1.3.0'
 
-    googleImplementation 'com.google.firebase:firebase-crash:11.8.0'
-    googleImplementation 'com.android.billingclient:billing:2.0.3'
+    //Gson
+    implementation 'com.google.code.gson:gson:2.8.6'
+
+    //RxJava
+    implementation 'io.reactivex.rxjava2:rxandroid:2.1.1'
+    implementation 'io.reactivex.rxjava2:rxjava:2.2.20'
+
+// Flavor
+    //googleImplementation 'com.google.firebase:firebase-crash:x.y.z'
+    googleImplementation 'com.android.billingclient:billing:2.2.0'
 
-    debugImplementation 'com.facebook.stetho:stetho:1.5.0'
+// Debug
+    debugImplementation 'com.facebook.stetho:stetho:1.5.1'
 
+// Testing
     testImplementation 'junit:junit:4.12'
     testImplementation 'org.mockito:mockito-core:1.9.0'
 }
diff --git a/app/src/google/java/com/physphil/android/unitconverterultimate/BillingManager.kt b/app/src/google/java/com/physphil/android/unitconverterultimate/BillingManager.kt
index 4b387024..a9e06e9e 100644
--- a/app/src/google/java/com/physphil/android/unitconverterultimate/BillingManager.kt
+++ b/app/src/google/java/com/physphil/android/unitconverterultimate/BillingManager.kt
@@ -1,7 +1,7 @@
 package com.physphil.android.unitconverterultimate
 
-import android.app.Activity
 import android.content.Context
+import androidx.appcompat.app.AppCompatActivity
 import com.android.billingclient.api.BillingClient
 import com.android.billingclient.api.BillingClientStateListener
 import com.android.billingclient.api.BillingFlowParams
@@ -76,7 +76,7 @@ class BillingManager : PurchasesUpdatedListener {
         }
     }
 
-    fun donate(activity: Activity, donation: SkuDetails, listener: DonationResultListener) {
+    fun donate(activity: AppCompatActivity, donation: SkuDetails, listener: DonationResultListener) {
         donationResultListener = listener
         val flowParams = BillingFlowParams.newBuilder()
             .setSkuDetails(donation)
diff --git a/app/src/main/java/com/physphil/android/unitconverterultimate/api/CurrencyApi.java b/app/src/main/java/com/physphil/android/unitconverterultimate/api/CurrencyApi.java
index 5155bb64..018432a0 100644
--- a/app/src/main/java/com/physphil/android/unitconverterultimate/api/CurrencyApi.java
+++ b/app/src/main/java/com/physphil/android/unitconverterultimate/api/CurrencyApi.java
@@ -17,7 +17,7 @@
 package com.physphil.android.unitconverterultimate.api;
 
 import retrofit2.Retrofit;
-import retrofit2.adapter.rxjava.RxJavaCallAdapterFactory;
+import retrofit2.adapter.rxjava2.RxJava2CallAdapterFactory;
 import retrofit2.converter.simplexml.SimpleXmlConverterFactory;
 
 /**
@@ -34,7 +34,7 @@ private CurrencyApi() {
         Retrofit retrofit = new Retrofit.Builder()
                 .baseUrl(BASE_URL)
                 .addConverterFactory(SimpleXmlConverterFactory.create())
-                .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
+                .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
                 .build();
 
         mService = retrofit.create(CurrencyService.class);
diff --git a/app/src/main/java/com/physphil/android/unitconverterultimate/api/CurrencyService.java b/app/src/main/java/com/physphil/android/unitconverterultimate/api/CurrencyService.java
index 9334f050..bf6ce65e 100644
--- a/app/src/main/java/com/physphil/android/unitconverterultimate/api/CurrencyService.java
+++ b/app/src/main/java/com/physphil/android/unitconverterultimate/api/CurrencyService.java
@@ -18,8 +18,8 @@
 
 import com.physphil.android.unitconverterultimate.api.models.Envelope;
 
+import io.reactivex.Observable;
 import retrofit2.http.GET;
-import rx.Observable;
 
 /**
  * Retrofit service to consume Currency API
diff --git a/app/src/main/java/com/physphil/android/unitconverterultimate/presenters/ConversionPresenter.java b/app/src/main/java/com/physphil/android/unitconverterultimate/presenters/ConversionPresenter.java
index d6cd743d..d0db4856 100644
--- a/app/src/main/java/com/physphil/android/unitconverterultimate/presenters/ConversionPresenter.java
+++ b/app/src/main/java/com/physphil/android/unitconverterultimate/presenters/ConversionPresenter.java
@@ -32,13 +32,13 @@
 import java.math.RoundingMode;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.Callable;
 
-import rx.Observable;
-import rx.android.schedulers.AndroidSchedulers;
-import rx.functions.Action1;
-import rx.functions.Func0;
-import rx.schedulers.Schedulers;
-import rx.subscriptions.CompositeSubscription;
+import io.reactivex.Observable;
+import io.reactivex.android.schedulers.AndroidSchedulers;
+import io.reactivex.disposables.CompositeDisposable;
+import io.reactivex.functions.Consumer;
+import io.reactivex.schedulers.Schedulers;
 
 /**
  * Presenter to handle unit conversions
@@ -46,7 +46,7 @@
  */
 public class ConversionPresenter {
 
-    private CompositeSubscription mCompositeSubscription;
+    private CompositeDisposable mCompositeDisposable;
     private ConversionView mView;
 
     /**
@@ -56,33 +56,33 @@ public class ConversionPresenter {
      */
     public ConversionPresenter(ConversionView mView) {
         this.mView = mView;
-        this.mCompositeSubscription = new CompositeSubscription();
+        this.mCompositeDisposable = new CompositeDisposable();
     }
 
     public void onDestroy() {
         // Clear all observable subscriptions
-        mCompositeSubscription.unsubscribe();
+        mCompositeDisposable.dispose();
     }
 
     public void getLastConversionState(@Conversion.id final int conversionId) {
-        mCompositeSubscription.add(getConversionStateObservable(conversionId)
+        mCompositeDisposable.add(getConversionStateObservable(conversionId)
                 .subscribeOn(Schedulers.io())
                 .observeOn(AndroidSchedulers.mainThread())
-                .subscribe(new Action1<ConversionState>() {
+                .subscribe(new Consumer<ConversionState>() {
                     @Override
-                    public void call(ConversionState conversionState) {
+                    public void accept(ConversionState conversionState) {
                         mView.restoreConversionState(conversionState);
                     }
-                }, new Action1<Throwable>() {
+                }, new Consumer<Throwable>() {
                     @Override
-                    public void call(Throwable throwable) {
+                    public void accept(Throwable throwable) {
                         // This should never happen
                     }
                 }));
     }
 
     private Observable<ConversionState> getConversionStateObservable(@Conversion.id final int conversionId) {
-        return Observable.defer(new Func0<Observable<ConversionState>>() {
+        return Observable.defer(new Callable<Observable<ConversionState>>() {
             @Override
             public Observable<ConversionState> call() {
                 return Observable.just(DataAccess.getInstance(mView.getContext()).getConversionState(conversionId));
@@ -91,13 +91,13 @@ public Observable<ConversionState> call() {
     }
 
     public void onUpdateCurrencyConversions() {
-        mCompositeSubscription.add(CurrencyApi.getInstance().getService()
+        mCompositeDisposable.add(CurrencyApi.getInstance().getService()
                 .getLatestRates()
                 .subscribeOn(Schedulers.io())
                 .observeOn(AndroidSchedulers.mainThread())
-                .subscribe(new Action1<Envelope>() {
+                .subscribe(new Consumer<Envelope>() {
                     @Override
-                    public void call(Envelope envelope) {
+                    public void accept(Envelope envelope) {
                         List<Currency> currencies = new ArrayList<>();
                         for (Envelope.Cube cube : envelope.getCube().getCube().get(0).getCube()) {
                             currencies.add(new Currency(cube.getCurrency(), cube.getRate()));
@@ -115,9 +115,9 @@ public void call(Envelope envelope) {
                             mView.showUnitsList(Conversions.getInstance().getById(Conversion.CURRENCY));
                         }
                     }
-                }, new Action1<Throwable>() {
+                }, new Consumer<Throwable>() {
                     @Override
-                    public void call(Throwable throwable) {
+                    public void accept(Throwable throwable) {
                         if (!Conversions.getInstance().hasCurrency()) {
                             mView.showLoadingError(R.string.error_loading_currency);
                         }
diff --git a/build.gradle b/build.gradle
index 1aefe6e2..369a833a 100644
--- a/build.gradle
+++ b/build.gradle
@@ -16,15 +16,15 @@
 
 // Top-level build file where you can add configuration options common to all sub-projects/modules.
 buildscript {
-    ext.kotlin_version = '1.3.50'
+    ext.kotlin_version = '1.4.10'
     repositories {
         mavenCentral()
         jcenter()
         google()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:3.5.2'
-        classpath 'com.google.gms:google-services:3.1.2'
+        classpath 'com.android.tools.build:gradle:4.1.1'
+        classpath 'com.google.gms:google-services:4.3.4'
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
     }
 }
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
index 8c0fb64a..e708b1c0 100644
Binary files a/gradle/wrapper/gradle-wrapper.jar and b/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index aaf1e34c..14e30f74 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,6 +1,5 @@
-#Tue Sep 17 21:07:02 EDT 2019
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.7-all.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-5.4.1-all.zip
diff --git a/gradlew b/gradlew
index 91a7e269..4f906e0c 100644
--- a/gradlew
+++ b/gradlew
@@ -1,4 +1,20 @@
-#!/usr/bin/env bash
+#!/usr/bin/env sh
+
+#
+# Copyright 2015 the original author or authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
 
 ##############################################################################
 ##
@@ -6,20 +22,38 @@
 ##
 ##############################################################################
 
-# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-DEFAULT_JVM_OPTS=""
+# Attempt to set APP_HOME
+# Resolve links: $0 may be a link
+PRG="$0"
+# Need this for relative symlinks.
+while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+        PRG="$link"
+    else
+        PRG=`dirname "$PRG"`"/$link"
+    fi
+done
+SAVED="`pwd`"
+cd "`dirname \"$PRG\"`/" >/dev/null
+APP_HOME="`pwd -P`"
+cd "$SAVED" >/dev/null
 
 APP_NAME="Gradle"
 APP_BASE_NAME=`basename "$0"`
 
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
 # Use the maximum available, or set MAX_FD != -1 to use that value.
 MAX_FD="maximum"
 
-warn ( ) {
+warn () {
     echo "$*"
 }
 
-die ( ) {
+die () {
     echo
     echo "$*"
     echo
@@ -30,6 +64,7 @@ die ( ) {
 cygwin=false
 msys=false
 darwin=false
+nonstop=false
 case "`uname`" in
   CYGWIN* )
     cygwin=true
@@ -40,33 +75,14 @@ case "`uname`" in
   MINGW* )
     msys=true
     ;;
+  NONSTOP* )
+    nonstop=true
+    ;;
 esac
 
-# For Cygwin, ensure paths are in UNIX format before anything is touched.
-if $cygwin ; then
-    [ -n "$JAVA_HOME" ] && JAVA_HOME=`cygpath --unix "$JAVA_HOME"`
-fi
-
-# Attempt to set APP_HOME
-# Resolve links: $0 may be a link
-PRG="$0"
-# Need this for relative symlinks.
-while [ -h "$PRG" ] ; do
-    ls=`ls -ld "$PRG"`
-    link=`expr "$ls" : '.*-> \(.*\)$'`
-    if expr "$link" : '/.*' > /dev/null; then
-        PRG="$link"
-    else
-        PRG=`dirname "$PRG"`"/$link"
-    fi
-done
-SAVED="`pwd`"
-cd "`dirname \"$PRG\"`/" >&-
-APP_HOME="`pwd -P`"
-cd "$SAVED" >&-
-
 CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
 
+
 # Determine the Java command to use to start the JVM.
 if [ -n "$JAVA_HOME" ] ; then
     if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
@@ -90,7 +106,7 @@ location of your Java installation."
 fi
 
 # Increase the maximum file descriptors if we can.
-if [ "$cygwin" = "false" -a "$darwin" = "false" ] ; then
+if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
     MAX_FD_LIMIT=`ulimit -H -n`
     if [ $? -eq 0 ] ; then
         if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
@@ -110,11 +126,13 @@ if $darwin; then
     GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
 fi
 
-# For Cygwin, switch paths to Windows format before running java
-if $cygwin ; then
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if [ "$cygwin" = "true" -o "$msys" = "true" ] ; then
     APP_HOME=`cygpath --path --mixed "$APP_HOME"`
     CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
 
+    JAVACMD=`cygpath --unix "$JAVACMD"`
+
     # We build the pattern for arguments to be converted via cygpath
     ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
     SEP=""
@@ -138,27 +156,30 @@ if $cygwin ; then
         else
             eval `echo args$i`="\"$arg\""
         fi
-        i=$((i+1))
+        i=`expr $i + 1`
     done
     case $i in
-        (0) set -- ;;
-        (1) set -- "$args0" ;;
-        (2) set -- "$args0" "$args1" ;;
-        (3) set -- "$args0" "$args1" "$args2" ;;
-        (4) set -- "$args0" "$args1" "$args2" "$args3" ;;
-        (5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
-        (6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
-        (7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
-        (8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
-        (9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+        0) set -- ;;
+        1) set -- "$args0" ;;
+        2) set -- "$args0" "$args1" ;;
+        3) set -- "$args0" "$args1" "$args2" ;;
+        4) set -- "$args0" "$args1" "$args2" "$args3" ;;
+        5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
+        6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
+        7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
+        8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
+        9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
     esac
 fi
 
-# Split up the JVM_OPTS And GRADLE_OPTS values into an array, following the shell quoting and substitution rules
-function splitJvmOpts() {
-    JVM_OPTS=("$@")
+# Escape application args
+save () {
+    for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
+    echo " "
 }
-eval splitJvmOpts $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS
-JVM_OPTS[${#JVM_OPTS[*]}]="-Dorg.gradle.appname=$APP_BASE_NAME"
+APP_ARGS=`save "$@"`
+
+# Collect all arguments for the java command, following the shell quoting and substitution rules
+eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
 
-exec "$JAVACMD" "${JVM_OPTS[@]}" -classpath "$CLASSPATH" org.gradle.wrapper.GradleWrapperMain "$@"
+exec "$JAVACMD" "$@"
diff --git a/gradlew.bat b/gradlew.bat
index 8a0b282a..107acd32 100644
--- a/gradlew.bat
+++ b/gradlew.bat
@@ -1,3 +1,19 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
 @if "%DEBUG%" == "" @echo off
 @rem ##########################################################################
 @rem
@@ -8,20 +24,23 @@
 @rem Set local scope for the variables with windows NT shell
 if "%OS%"=="Windows_NT" setlocal
 
-@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-set DEFAULT_JVM_OPTS=
-
 set DIRNAME=%~dp0
 if "%DIRNAME%" == "" set DIRNAME=.
 set APP_BASE_NAME=%~n0
 set APP_HOME=%DIRNAME%
 
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
 @rem Find java.exe
 if defined JAVA_HOME goto findJavaFromJavaHome
 
 set JAVA_EXE=java.exe
 %JAVA_EXE% -version >NUL 2>&1
-if "%ERRORLEVEL%" == "0" goto init
+if "%ERRORLEVEL%" == "0" goto execute
 
 echo.
 echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
@@ -35,7 +54,7 @@ goto fail
 set JAVA_HOME=%JAVA_HOME:"=%
 set JAVA_EXE=%JAVA_HOME%/bin/java.exe
 
-if exist "%JAVA_EXE%" goto init
+if exist "%JAVA_EXE%" goto execute
 
 echo.
 echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
@@ -45,34 +64,14 @@ echo location of your Java installation.
 
 goto fail
 
-:init
-@rem Get command-line arguments, handling Windowz variants
-
-if not "%OS%" == "Windows_NT" goto win9xME_args
-if "%@eval[2+2]" == "4" goto 4NT_args
-
-:win9xME_args
-@rem Slurp the command line arguments.
-set CMD_LINE_ARGS=
-set _SKIP=2
-
-:win9xME_args_slurp
-if "x%~1" == "x" goto execute
-
-set CMD_LINE_ARGS=%*
-goto execute
-
-:4NT_args
-@rem Get arguments from the 4NT Shell from JP Software
-set CMD_LINE_ARGS=%$
-
 :execute
 @rem Setup the command line
 
 set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
 
+
 @rem Execute Gradle
-"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %CMD_LINE_ARGS%
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
 
 :end
 @rem End local scope for the variables with windows NT shell
diff --git a/v6000/.gitignore b/v6000/.gitignore
deleted file mode 100644
index 796b96d1..00000000
--- a/v6000/.gitignore
+++ /dev/null
@@ -1 +0,0 @@
-/build
diff --git a/v6000/build.gradle b/v6000/build.gradle
index 71d5cdb4..05ce096a 100644
--- a/v6000/build.gradle
+++ b/v6000/build.gradle
@@ -1,17 +1,10 @@
 apply plugin: 'com.android.application'
 apply plugin: 'kotlin-android'
 apply plugin: 'kotlin-android-extensions'
+
 android {
     compileSdkVersion 29
-
-    compileOptions {
-        sourceCompatibility = 1.8
-        targetCompatibility = 1.8
-    }
-
-    kotlinOptions {
-        jvmTarget = "1.8"
-    }
+    buildToolsVersion "29.0.3"
 
     defaultConfig {
         applicationId "com.physphil.android.unitconverterultimate"
@@ -26,33 +19,43 @@ android {
     buildTypes {
         release {
             minifyEnabled false
-            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
+            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
         }
         debug {
             applicationIdSuffix ".debug"
         }
     }
 
+    compileOptions {
+        encoding "UTF-8"
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+
+    kotlinOptions {
+        jvmTarget = JavaVersion.VERSION_1_8.toString()
+    }
 }
 
 dependencies {
-    implementation fileTree(dir: 'libs', include: ['*.jar'])
-    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
+// Kotlin
+    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin_version"
 
-    implementation 'androidx.appcompat:appcompat:1.1.0'
-    implementation 'androidx.core:core-ktx:1.1.0'
-    implementation 'androidx.legacy:legacy-support-v4:1.0.0'
-    implementation 'androidx.lifecycle:lifecycle-extensions:2.1.0'
+// Android support
+    implementation 'androidx.appcompat:appcompat:1.2.0'
     implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
-    implementation 'androidx.navigation:navigation-fragment-ktx:2.1.0'
-    implementation 'androidx.navigation:navigation-ui-ktx:2.1.0'
-    implementation 'androidx.preference:preference:1.1.0'
-    implementation 'com.google.android.material:material:1.0.0'
-
+    implementation 'androidx.core:core-ktx:1.3.2'
+    implementation 'androidx.lifecycle:lifecycle-livedata-core-ktx:2.2.0'
+    implementation 'androidx.lifecycle:lifecycle-viewmodel-ktx:2.2.0'
+    implementation 'androidx.navigation:navigation-fragment-ktx:2.3.1'
+    implementation 'androidx.navigation:navigation-ui-ktx:2.3.1'
+    implementation 'androidx.preference:preference-ktx:1.1.1'
+    implementation 'com.google.android.material:material:1.2.1'
+
+// Testing
     testImplementation 'junit:junit:4.12'
     testImplementation 'com.google.truth:truth:1.0'
     testImplementation 'com.nhaarman.mockitokotlin2:mockito-kotlin:2.2.0'
-
     androidTestImplementation 'androidx.test:runner:1.2.0'
     androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
 }
diff --git a/v6000/proguard-rules.pro b/v6000/proguard-rules.pro
deleted file mode 100644
index f1b42451..00000000
--- a/v6000/proguard-rules.pro
+++ /dev/null
@@ -1,21 +0,0 @@
-# Add project specific ProGuard rules here.
-# You can control the set of applied configuration files using the
-# proguardFiles setting in build.gradle.
-#
-# For more details, see
-#   http://developer.android.com/guide/developing/tools/proguard.html
-
-# If your project uses WebView with JS, uncomment the following
-# and specify the fully qualified class name to the JavaScript interface
-# class:
-#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
-#   public *;
-#}
-
-# Uncomment this to preserve the line number information for
-# debugging stack traces.
-#-keepattributes SourceFile,LineNumberTable
-
-# If you keep the line number information, uncomment this to
-# hide the original source file name.
-#-renamesourcefileattribute SourceFile
diff --git a/v6000/src/androidTest/java/com/physphil/android/unitconverterultimate/ExampleInstrumentedTest.kt b/v6000/src/androidTest/java/com/physphil/android/unitconverterultimate/ExampleInstrumentedTest.kt
deleted file mode 100644
index 6a36a4c0..00000000
--- a/v6000/src/androidTest/java/com/physphil/android/unitconverterultimate/ExampleInstrumentedTest.kt
+++ /dev/null
@@ -1,24 +0,0 @@
-package com.physphil.android.unitconverterultimate
-
-import androidx.test.platform.app.InstrumentationRegistry
-import androidx.test.runner.AndroidJUnit4
-
-import org.junit.Test
-import org.junit.runner.RunWith
-
-import org.junit.Assert.*
-
-/**
- * Instrumented test, which will execute on an Android device.
- *
- * See [testing documentation](http://d.android.com/tools/testing).
- */
-@RunWith(AndroidJUnit4::class)
-class ExampleInstrumentedTest {
-    @Test
-    fun useAppContext() {
-        // Context of the app under test.
-        val appContext = InstrumentationRegistry.getInstrumentation().targetContext
-        assertEquals("com.physphil.android.unitconverterultimate", appContext.packageName)
-    }
-}
diff --git a/v6000/src/main/java/com/physphil/android/unitconverterultimate/ConversionFragment.kt b/v6000/src/main/java/com/physphil/android/unitconverterultimate/ConversionFragment.kt
index 66e4b3b7..71a94af1 100644
--- a/v6000/src/main/java/com/physphil/android/unitconverterultimate/ConversionFragment.kt
+++ b/v6000/src/main/java/com/physphil/android/unitconverterultimate/ConversionFragment.kt
@@ -11,7 +11,7 @@ import androidx.core.widget.doOnTextChanged
 import androidx.fragment.app.Fragment
 import androidx.lifecycle.LifecycleOwner
 import androidx.lifecycle.Observer
-import androidx.lifecycle.ViewModelProviders
+import androidx.lifecycle.ViewModelProvider
 import com.physphil.android.unitconverterultimate.conversion.ConversionRepository
 import com.physphil.android.unitconverterultimate.models.ConversionType
 import kotlinx.android.synthetic.main.fragment_conversion.*
@@ -39,7 +39,7 @@ class ConversionFragment : Fragment() {
             ?: throw IllegalArgumentException("Proper conversion type not specified when starting fragment")
 
         val factory = ConversionViewModel.Factory(conversionType, ConversionRepository())
-        conversionViewModel = ViewModelProviders.of(this, factory).get(ConversionViewModel::class.java)
+        conversionViewModel = ViewModelProvider(this, factory).get(ConversionViewModel::class.java)
         conversionViewModel.init(this)
         initViewListeners()
     }
diff --git a/v6000/src/main/java/com/physphil/android/unitconverterultimate/settings/SettingsFragment.kt b/v6000/src/main/java/com/physphil/android/unitconverterultimate/settings/SettingsFragment.kt
index 100dd888..ddf021b9 100644
--- a/v6000/src/main/java/com/physphil/android/unitconverterultimate/settings/SettingsFragment.kt
+++ b/v6000/src/main/java/com/physphil/android/unitconverterultimate/settings/SettingsFragment.kt
@@ -7,7 +7,7 @@ import android.os.Bundle
 import androidx.core.content.ContextCompat
 import androidx.lifecycle.LifecycleOwner
 import androidx.lifecycle.Observer
-import androidx.lifecycle.ViewModelProviders
+import androidx.lifecycle.ViewModelProvider
 import androidx.navigation.fragment.findNavController
 import androidx.preference.ListPreference
 import androidx.preference.Preference
@@ -24,7 +24,7 @@ class SettingsFragment : PreferenceFragmentCompat() {
     override fun onActivityCreated(savedInstanceState: Bundle?) {
         super.onActivityCreated(savedInstanceState)
 
-        val viewModel = ViewModelProviders.of(this).get(SettingsViewModel::class.java)
+        val viewModel = ViewModelProvider(this).get(SettingsViewModel::class.java)
         viewModel.init(this)
 
         findPreference<ListPreference>(SettingsViewModel.Keys.LANGUAGE)?.let { language ->
diff --git a/v6000/src/main/java/com/physphil/android/unitconverterultimate/ui/gallery/GalleryFragment.kt b/v6000/src/main/java/com/physphil/android/unitconverterultimate/ui/gallery/GalleryFragment.kt
index 1e018844..0c715970 100644
--- a/v6000/src/main/java/com/physphil/android/unitconverterultimate/ui/gallery/GalleryFragment.kt
+++ b/v6000/src/main/java/com/physphil/android/unitconverterultimate/ui/gallery/GalleryFragment.kt
@@ -7,7 +7,7 @@ import android.view.ViewGroup
 import android.widget.TextView
 import androidx.fragment.app.Fragment
 import androidx.lifecycle.Observer
-import androidx.lifecycle.ViewModelProviders
+import androidx.lifecycle.ViewModelProvider
 import com.physphil.android.unitconverterultimate.R
 
 class GalleryFragment : Fragment() {
@@ -20,7 +20,7 @@ class GalleryFragment : Fragment() {
         savedInstanceState: Bundle?
     ): View? {
         galleryViewModel =
-            ViewModelProviders.of(this).get(GalleryViewModel::class.java)
+            ViewModelProvider(this).get(GalleryViewModel::class.java)
         val root = inflater.inflate(R.layout.fragment_gallery, container, false)
         val textView: TextView = root.findViewById(R.id.text_gallery)
         galleryViewModel.text.observe(this, Observer {
diff --git a/v6000/src/main/java/com/physphil/android/unitconverterultimate/ui/home/HomeFragment.kt b/v6000/src/main/java/com/physphil/android/unitconverterultimate/ui/home/HomeFragment.kt
index 55ce0e86..df0ff02f 100644
--- a/v6000/src/main/java/com/physphil/android/unitconverterultimate/ui/home/HomeFragment.kt
+++ b/v6000/src/main/java/com/physphil/android/unitconverterultimate/ui/home/HomeFragment.kt
@@ -7,7 +7,7 @@ import android.view.ViewGroup
 import android.widget.TextView
 import androidx.fragment.app.Fragment
 import androidx.lifecycle.Observer
-import androidx.lifecycle.ViewModelProviders
+import androidx.lifecycle.ViewModelProvider
 import com.physphil.android.unitconverterultimate.R
 
 class HomeFragment : Fragment() {
@@ -20,7 +20,7 @@ class HomeFragment : Fragment() {
         savedInstanceState: Bundle?
     ): View? {
         homeViewModel =
-            ViewModelProviders.of(this).get(HomeViewModel::class.java)
+            ViewModelProvider(this).get(HomeViewModel::class.java)
         val root = inflater.inflate(R.layout.fragment_home, container, false)
         val textView: TextView = root.findViewById(R.id.text_home)
         homeViewModel.text.observe(this, Observer {
diff --git a/v6000/src/main/java/com/physphil/android/unitconverterultimate/ui/send/SendFragment.kt b/v6000/src/main/java/com/physphil/android/unitconverterultimate/ui/send/SendFragment.kt
index d85973c8..6c51d964 100644
--- a/v6000/src/main/java/com/physphil/android/unitconverterultimate/ui/send/SendFragment.kt
+++ b/v6000/src/main/java/com/physphil/android/unitconverterultimate/ui/send/SendFragment.kt
@@ -7,7 +7,7 @@ import android.view.ViewGroup
 import android.widget.TextView
 import androidx.fragment.app.Fragment
 import androidx.lifecycle.Observer
-import androidx.lifecycle.ViewModelProviders
+import androidx.lifecycle.ViewModelProvider
 import com.physphil.android.unitconverterultimate.R
 
 class SendFragment : Fragment() {
@@ -20,7 +20,7 @@ class SendFragment : Fragment() {
         savedInstanceState: Bundle?
     ): View? {
         sendViewModel =
-            ViewModelProviders.of(this).get(SendViewModel::class.java)
+            ViewModelProvider(this).get(SendViewModel::class.java)
         val root = inflater.inflate(R.layout.fragment_send, container, false)
         val textView: TextView = root.findViewById(R.id.text_send)
         sendViewModel.text.observe(this, Observer {
diff --git a/v6000/src/main/java/com/physphil/android/unitconverterultimate/ui/share/ShareFragment.kt b/v6000/src/main/java/com/physphil/android/unitconverterultimate/ui/share/ShareFragment.kt
index a7e627da..03bc1e19 100644
--- a/v6000/src/main/java/com/physphil/android/unitconverterultimate/ui/share/ShareFragment.kt
+++ b/v6000/src/main/java/com/physphil/android/unitconverterultimate/ui/share/ShareFragment.kt
@@ -7,7 +7,7 @@ import android.view.ViewGroup
 import android.widget.TextView
 import androidx.fragment.app.Fragment
 import androidx.lifecycle.Observer
-import androidx.lifecycle.ViewModelProviders
+import androidx.lifecycle.ViewModelProvider
 import com.physphil.android.unitconverterultimate.R
 
 class ShareFragment : Fragment() {
@@ -20,7 +20,7 @@ class ShareFragment : Fragment() {
         savedInstanceState: Bundle?
     ): View? {
         shareViewModel =
-            ViewModelProviders.of(this).get(ShareViewModel::class.java)
+            ViewModelProvider(this).get(ShareViewModel::class.java)
         val root = inflater.inflate(R.layout.fragment_share, container, false)
         val textView: TextView = root.findViewById(R.id.text_share)
         shareViewModel.text.observe(this, Observer {
diff --git a/v6000/src/main/java/com/physphil/android/unitconverterultimate/ui/slideshow/SlideshowFragment.kt b/v6000/src/main/java/com/physphil/android/unitconverterultimate/ui/slideshow/SlideshowFragment.kt
index b9dc3777..16de6aad 100644
--- a/v6000/src/main/java/com/physphil/android/unitconverterultimate/ui/slideshow/SlideshowFragment.kt
+++ b/v6000/src/main/java/com/physphil/android/unitconverterultimate/ui/slideshow/SlideshowFragment.kt
@@ -7,7 +7,7 @@ import android.view.ViewGroup
 import android.widget.TextView
 import androidx.fragment.app.Fragment
 import androidx.lifecycle.Observer
-import androidx.lifecycle.ViewModelProviders
+import androidx.lifecycle.ViewModelProvider
 import com.physphil.android.unitconverterultimate.R
 
 class SlideshowFragment : Fragment() {
@@ -20,7 +20,7 @@ class SlideshowFragment : Fragment() {
         savedInstanceState: Bundle?
     ): View? {
         slideshowViewModel =
-            ViewModelProviders.of(this).get(SlideshowViewModel::class.java)
+            ViewModelProvider(this).get(SlideshowViewModel::class.java)
         val root = inflater.inflate(R.layout.fragment_slideshow, container, false)
         val textView: TextView = root.findViewById(R.id.text_slideshow)
         slideshowViewModel.text.observe(this, Observer {
diff --git a/v6000/src/main/java/com/physphil/android/unitconverterultimate/ui/tools/ToolsFragment.kt b/v6000/src/main/java/com/physphil/android/unitconverterultimate/ui/tools/ToolsFragment.kt
index 79738eb3..44068eac 100644
--- a/v6000/src/main/java/com/physphil/android/unitconverterultimate/ui/tools/ToolsFragment.kt
+++ b/v6000/src/main/java/com/physphil/android/unitconverterultimate/ui/tools/ToolsFragment.kt
@@ -7,7 +7,7 @@ import android.view.ViewGroup
 import android.widget.TextView
 import androidx.fragment.app.Fragment
 import androidx.lifecycle.Observer
-import androidx.lifecycle.ViewModelProviders
+import androidx.lifecycle.ViewModelProvider
 import com.physphil.android.unitconverterultimate.R
 
 class ToolsFragment : Fragment() {
@@ -20,7 +20,7 @@ class ToolsFragment : Fragment() {
         savedInstanceState: Bundle?
     ): View? {
         toolsViewModel =
-            ViewModelProviders.of(this).get(ToolsViewModel::class.java)
+            ViewModelProvider(this).get(ToolsViewModel::class.java)
         val root = inflater.inflate(R.layout.fragment_tools, container, false)
         val textView: TextView = root.findViewById(R.id.text_tools)
         toolsViewModel.text.observe(this, Observer {