diff --git a/app/src/main/java/com/todoroo/astrid/activity/TaskListFragment.kt b/app/src/main/java/com/todoroo/astrid/activity/TaskListFragment.kt
index 8ba822497..0ecd1e90a 100644
--- a/app/src/main/java/com/todoroo/astrid/activity/TaskListFragment.kt
+++ b/app/src/main/java/com/todoroo/astrid/activity/TaskListFragment.kt
@@ -603,8 +603,9 @@ class TaskListFragment : Fragment(), OnRefreshListener, Toolbar.OnMenuItemClickL
                     val match: List<String>? = data!!.getStringArrayListExtra(RecognizerIntent.EXTRA_RESULTS)
                     if (match != null && match.isNotEmpty() && match[0].isNotEmpty()) {
                         var recognizedSpeech = match[0]
-                        recognizedSpeech = (recognizedSpeech.substring(0, 1).toUpperCase()
-                                + recognizedSpeech.substring(1).toLowerCase())
+                        recognizedSpeech = (recognizedSpeech.substring(0, 1)
+                            .uppercase(Locale.getDefault())
+                                + recognizedSpeech.substring(1).lowercase(Locale.getDefault()))
                         onTaskListItemClicked(addTask(recognizedSpeech))
                         firebase.addTask("voice")
                     }
diff --git a/app/src/main/java/com/todoroo/astrid/api/Filter.java b/app/src/main/java/com/todoroo/astrid/api/Filter.java
index 811c47659..71d598dfc 100644
--- a/app/src/main/java/com/todoroo/astrid/api/Filter.java
+++ b/app/src/main/java/com/todoroo/astrid/api/Filter.java
@@ -150,13 +150,8 @@ public class Filter extends FilterListItem {
       return false;
     }
     if (listingTitle == null) {
-      if (other.listingTitle != null) {
-        return false;
-      }
-    } else if (!listingTitle.equals(other.listingTitle)) {
-      return false;
-    }
-    return true;
+      return other.listingTitle == null;
+    } else return listingTitle.equals(other.listingTitle);
   }
 
   @Override
diff --git a/app/src/main/java/com/todoroo/astrid/core/CriterionInstance.kt b/app/src/main/java/com/todoroo/astrid/core/CriterionInstance.kt
index 7cd2dc3a6..921cb3f5f 100644
--- a/app/src/main/java/com/todoroo/astrid/core/CriterionInstance.kt
+++ b/app/src/main/java/com/todoroo/astrid/core/CriterionInstance.kt
@@ -111,7 +111,7 @@ class CriterionInstance {
         result = 31 * result + end
         result = 31 * result + start
         result = 31 * result + max
-        result = 31 * result + (id.hashCode() ?: 0)
+        result = 31 * result + id.hashCode()
         return result
     }
 
diff --git a/app/src/main/java/com/todoroo/astrid/notes/CommentsController.kt b/app/src/main/java/com/todoroo/astrid/notes/CommentsController.kt
index d96fa3927..c1afc0ef8 100644
--- a/app/src/main/java/com/todoroo/astrid/notes/CommentsController.kt
+++ b/app/src/main/java/com/todoroo/astrid/notes/CommentsController.kt
@@ -98,7 +98,7 @@ class CommentsController @Inject constructor(
 
         // delete button
         val deleteBtn = view.findViewById<ImageView>(R.id.clear)
-        deleteBtn.setOnClickListener(){
+        deleteBtn.setOnClickListener {
             val builder = AlertDialog.Builder(commentsContainer!!.context)
 
             // Display a message on alert dialog
diff --git a/app/src/main/java/com/todoroo/astrid/ui/ReminderControlSet.kt b/app/src/main/java/com/todoroo/astrid/ui/ReminderControlSet.kt
index 275d36efb..d42adfe66 100644
--- a/app/src/main/java/com/todoroo/astrid/ui/ReminderControlSet.kt
+++ b/app/src/main/java/com/todoroo/astrid/ui/ReminderControlSet.kt
@@ -48,8 +48,8 @@ class ReminderControlSet : TaskEditControlFragment() {
 
     override fun createView(savedInstanceState: Bundle?) {
         when {
-            viewModel.ringNonstop!! -> setRingMode(2)
-            viewModel.ringFiveTimes!! -> setRingMode(1)
+            viewModel.ringNonstop -> setRingMode(2)
+            viewModel.ringFiveTimes -> setRingMode(1)
             else -> setRingMode(0)
         }
     }
@@ -57,8 +57,8 @@ class ReminderControlSet : TaskEditControlFragment() {
     private fun onClickRingType() {
         val modes = resources.getStringArray(R.array.reminder_ring_modes)
         val ringMode = when {
-            viewModel.ringNonstop == true -> 2
-            viewModel.ringFiveTimes == true -> 1
+            viewModel.ringNonstop -> 2
+            viewModel.ringFiveTimes -> 1
             else -> 0
         }
         dialogBuilder
diff --git a/app/src/main/java/com/todoroo/astrid/utility/TitleParser.kt b/app/src/main/java/com/todoroo/astrid/utility/TitleParser.kt
index ee59118f8..1cc19651d 100644
--- a/app/src/main/java/com/todoroo/astrid/utility/TitleParser.kt
+++ b/app/src/main/java/com/todoroo/astrid/utility/TitleParser.kt
@@ -78,7 +78,7 @@ object TitleParser {
     }
 
     private fun strToPriority(priorityStr: String?): Int {
-        priorityStr?.toLowerCase()?.trim { it <= ' ' }
+        priorityStr?.lowercase(Locale.getDefault())?.trim { it <= ' ' }
         var priority = Task.Priority.HIGH
         if ("0" == priorityStr || "!0" == priorityStr || "least" == priorityStr || "lowest" == priorityStr) {
             priority = Task.Priority.NONE
@@ -124,7 +124,7 @@ object TitleParser {
         if (amPmString == null) {
             return time
         }
-        val text = amPmString.toLowerCase().trim { it <= ' ' }
+        val text = amPmString.lowercase(Locale.getDefault()).trim { it <= ' ' }
         if (text == "am" || text == "a.m" || text == "a") {
             time = Calendar.AM
         }
diff --git a/app/src/main/java/org/tasks/activities/NavigationDrawerCustomization.kt b/app/src/main/java/org/tasks/activities/NavigationDrawerCustomization.kt
index 3284f9a43..90b9fafa3 100644
--- a/app/src/main/java/org/tasks/activities/NavigationDrawerCustomization.kt
+++ b/app/src/main/java/org/tasks/activities/NavigationDrawerCustomization.kt
@@ -146,7 +146,7 @@ class NavigationDrawerCustomization : ThemedInjectingAppCompatActivity(), Toolba
         }
     }
 
-    private inner class ItemTouchHelperCallback : ItemTouchHelper.Callback() {
+    private inner class ItemTouchHelperCallback : Callback() {
         private var from = -1
         private var to = -1
 
diff --git a/app/src/main/java/org/tasks/auth/Configuration.kt b/app/src/main/java/org/tasks/auth/Configuration.kt
index 45716c876..79a242f5d 100644
--- a/app/src/main/java/org/tasks/auth/Configuration.kt
+++ b/app/src/main/java/org/tasks/auth/Configuration.kt
@@ -62,7 +62,6 @@ class Configuration constructor(
     var userInfoEndpointUri: Uri? = null
         private set
     private var isHttpsRequired = false
-        private set
 
     /**
      * Indicates whether the configuration has changed from the last known valid state.
@@ -203,8 +202,8 @@ class Configuration constructor(
         }
 
     class InvalidConfigurationException : Exception {
-        internal constructor(reason: String?) : super(reason) {}
-        internal constructor(reason: String?, cause: Throwable?) : super(reason, cause) {}
+        internal constructor(reason: String?) : super(reason)
+        internal constructor(reason: String?, cause: Throwable?) : super(reason, cause)
     }
 
     companion object {
diff --git a/app/src/main/java/org/tasks/caldav/CaldavSynchronizer.kt b/app/src/main/java/org/tasks/caldav/CaldavSynchronizer.kt
index 46604739e..dddf976d8 100644
--- a/app/src/main/java/org/tasks/caldav/CaldavSynchronizer.kt
+++ b/app/src/main/java/org/tasks/caldav/CaldavSynchronizer.kt
@@ -31,7 +31,7 @@ import net.fortuna.ical4j.model.property.ProdId
 import okhttp3.Headers
 import okhttp3.HttpUrl
 import okhttp3.OkHttpClient
-import okhttp3.RequestBody
+import okhttp3.RequestBody.Companion.toRequestBody
 import org.tasks.BuildConfig
 import org.tasks.LocalBroadcastManager
 import org.tasks.R
@@ -355,7 +355,7 @@ class CaldavSynchronizer @Inject constructor(
             return
         }
         val data = iCal.toVtodo(account, calendar, caldavTask, task)
-        val requestBody = RequestBody.create(MIME_ICALENDAR, data)
+        val requestBody = data.toRequestBody(contentType = MIME_ICALENDAR)
         try {
             val remote = DavResource(
                     httpClient, httpUrl.newBuilder().addPathSegment(caldavTask.`object`!!).build())
diff --git a/app/src/main/java/org/tasks/compose/Constants.kt b/app/src/main/java/org/tasks/compose/Constants.kt
index ddc938a1a..687035091 100644
--- a/app/src/main/java/org/tasks/compose/Constants.kt
+++ b/app/src/main/java/org/tasks/compose/Constants.kt
@@ -23,7 +23,7 @@ object Constants {
             colors = textButtonColors()
         ) {
             Text(
-                stringResource(text).toUpperCase(Locale.getDefault()),
+                stringResource(text).uppercase(Locale.getDefault()),
                 style = MaterialTheme.typography.button
             )
         }
diff --git a/app/src/main/java/org/tasks/compose/PrincipalList.kt b/app/src/main/java/org/tasks/compose/PrincipalList.kt
index f1e50172d..27166750a 100644
--- a/app/src/main/java/org/tasks/compose/PrincipalList.kt
+++ b/app/src/main/java/org/tasks/compose/PrincipalList.kt
@@ -59,7 +59,7 @@ private fun Owner() = MaterialTheme {
 @Preview(showBackground = true)
 @Preview(showBackground = true, backgroundColor = 0x202124, uiMode = UI_MODE_NIGHT_YES)
 @Composable
-private fun NotOwner() = MaterialTheme() {
+private fun NotOwner() = MaterialTheme {
     ListSettingsComposables.PrincipalList(principals, null)
 }
 
@@ -117,7 +117,7 @@ object ListSettingsComposables {
             ) {
                 Column {
                     Text(
-                        principal.name!!,
+                        principal.name,
                         style = MaterialTheme.typography.body1,
                         color = colors.onBackground,
                     )
diff --git a/app/src/main/java/org/tasks/data/CaldavDao.kt b/app/src/main/java/org/tasks/data/CaldavDao.kt
index 98c70b006..d904ccf41 100644
--- a/app/src/main/java/org/tasks/data/CaldavDao.kt
+++ b/app/src/main/java/org/tasks/data/CaldavDao.kt
@@ -336,7 +336,7 @@ GROUP BY caldav_lists.cdl_uuid
     }
 
     private suspend fun getLocalAccount() = getAccountByUuid(LOCAL) ?: CaldavAccount().apply {
-        accountType = CaldavAccount.TYPE_LOCAL
+        accountType = TYPE_LOCAL
         uuid = LOCAL
         id = insert(this)
     }
diff --git a/app/src/main/java/org/tasks/data/MyAndroidTask.kt b/app/src/main/java/org/tasks/data/MyAndroidTask.kt
index f852eeb59..259fb6954 100644
--- a/app/src/main/java/org/tasks/data/MyAndroidTask.kt
+++ b/app/src/main/java/org/tasks/data/MyAndroidTask.kt
@@ -75,7 +75,7 @@ class MyAndroidTask() : AndroidTask(null) {
                     TaskContract.Property.Alarm.ALARM_REFERENCE_START_DATE
             }
 
-            val alarmType = when (alarm.action?.value?.toUpperCase(Locale.ROOT)) {
+            val alarmType = when (alarm.action?.value?.uppercase(Locale.ROOT)) {
                 Action.AUDIO.value ->
                     TaskContract.Property.Alarm.ALARM_TYPE_SOUND
                 Action.DISPLAY.value ->
diff --git a/app/src/main/java/org/tasks/data/PlaceUsage.kt b/app/src/main/java/org/tasks/data/PlaceUsage.kt
index 340958963..547e62403 100644
--- a/app/src/main/java/org/tasks/data/PlaceUsage.kt
+++ b/app/src/main/java/org/tasks/data/PlaceUsage.kt
@@ -10,7 +10,7 @@ class PlaceUsage {
         get() = place.color
 
     val icon: Int
-        get() = place.getIcon()!!
+        get() = place.getIcon()
 
     override fun equals(other: Any?): Boolean {
         if (this === other) return true
diff --git a/app/src/main/java/org/tasks/drive/DriveInvoker.kt b/app/src/main/java/org/tasks/drive/DriveInvoker.kt
index 1a90832e9..13b61c54c 100644
--- a/app/src/main/java/org/tasks/drive/DriveInvoker.kt
+++ b/app/src/main/java/org/tasks/drive/DriveInvoker.kt
@@ -74,7 +74,7 @@ class DriveInvoker(
                 .setParents(listOf(folderId))
                 .setMimeType(mime)
                 .setName(FileHelper.getFilename(context, uri))
-        val content = InputStreamContent(mime, context.contentResolver.openInputStream(uri!!))
+        val content = InputStreamContent(mime, context.contentResolver.openInputStream(uri))
         return execute(service.files().create(metadata, content))
     }
 
diff --git a/app/src/main/java/org/tasks/filters/AlphanumComparator.kt b/app/src/main/java/org/tasks/filters/AlphanumComparator.kt
index 9d226d0d8..cb5542403 100644
--- a/app/src/main/java/org/tasks/filters/AlphanumComparator.kt
+++ b/app/src/main/java/org/tasks/filters/AlphanumComparator.kt
@@ -41,7 +41,7 @@ import java.util.*
  * Collections.sort(your list, new AlphanumComparator());
  */
 class AlphanumComparator<T>(private val getTitle: (T) -> String?) : Comparator<T> {
-    private fun isDigit(ch: Char): Boolean = ch.toInt() in 48..57
+    private fun isDigit(ch: Char): Boolean = ch.code in 48..57
 
     /** Length of string is passed in for improved efficiency (only need to calculate it once) *  */
     private fun getChunk(s: String, slength: Int, marker: Int): String {
diff --git a/app/src/main/java/org/tasks/tasklist/DragAndDropRecyclerAdapter.kt b/app/src/main/java/org/tasks/tasklist/DragAndDropRecyclerAdapter.kt
index eae3e0dc3..b684f01a2 100644
--- a/app/src/main/java/org/tasks/tasklist/DragAndDropRecyclerAdapter.kt
+++ b/app/src/main/java/org/tasks/tasklist/DragAndDropRecyclerAdapter.kt
@@ -111,7 +111,7 @@ class DragAndDropRecyclerAdapter(
 
     override fun getItemCount() = items.size
 
-    private inner class ItemTouchHelperCallback : ItemTouchHelper.Callback() {
+    private inner class ItemTouchHelperCallback : Callback() {
         private var from = -1
         private var to = -1
         override fun onSelectedChanged(viewHolder: RecyclerView.ViewHolder?, actionState: Int) {
diff --git a/app/src/main/java/org/tasks/ui/ListFragment.kt b/app/src/main/java/org/tasks/ui/ListFragment.kt
index c4e772dd7..2ed33f2b0 100644
--- a/app/src/main/java/org/tasks/ui/ListFragment.kt
+++ b/app/src/main/java/org/tasks/ui/ListFragment.kt
@@ -29,7 +29,7 @@ class ListFragment : TaskEditControlFragment() {
                         colorProvider = { chipProvider.getColor(it) },
                         onClick = {
                             ListPicker.newListPicker(
-                                viewModel.selectedList.value!!,
+                                viewModel.selectedList.value,
                                 this@ListFragment,
                                 REQUEST_CODE_SELECT_LIST
                             )
diff --git a/app/src/test/java/com/todoroo/astrid/repeats/RepeatTests.kt b/app/src/test/java/com/todoroo/astrid/repeats/RepeatTests.kt
index 92fa7aa61..17f0fcf36 100644
--- a/app/src/test/java/com/todoroo/astrid/repeats/RepeatTests.kt
+++ b/app/src/test/java/com/todoroo/astrid/repeats/RepeatTests.kt
@@ -16,13 +16,13 @@ import org.tasks.makers.TaskMaker
 import org.tasks.time.DateTime
 
 abstract class RepeatTests {
-    private val alarmService = Mockito.mock(AlarmService::class.java)
+    private val alarmService = mock(AlarmService::class.java)
     private val helper = RepeatTaskHelper(
-            Mockito.mock(GCalHelper::class.java),
+            mock(GCalHelper::class.java),
             alarmService,
-            Mockito.mock(TaskDao::class.java),
-            Mockito.mock(LocalBroadcastManager::class.java),
-            Mockito.mock(TaskCompleter::class.java)
+            mock(TaskDao::class.java),
+            mock(LocalBroadcastManager::class.java),
+            mock(TaskCompleter::class.java)
     )
 
     @Before
diff --git a/app/src/test/java/org/tasks/caldav/NextCloudTests.kt b/app/src/test/java/org/tasks/caldav/NextCloudTests.kt
index 07bfee389..824c2db15 100644
--- a/app/src/test/java/org/tasks/caldav/NextCloudTests.kt
+++ b/app/src/test/java/org/tasks/caldav/NextCloudTests.kt
@@ -36,7 +36,8 @@ class NextCloudTests {
     fun readCreationDate() {
         assertEquals(
                 DateTime(2018, 4, 17, 11, 32, 3).millis,
-                vtodo("nextcloud/basic_no_due_date.txt").creationDate as Long)
+            vtodo("nextcloud/basic_no_due_date.txt").creationDate
+        )
     }
 
     @Test