diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/events/model/LocalEcho.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/events/model/LocalEcho.kt
index ca75871cda..1dbee475e0 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/events/model/LocalEcho.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/events/model/LocalEcho.kt
@@ -16,7 +16,7 @@
 
 package im.vector.matrix.android.api.session.events.model
 
-import java.util.*
+import java.util.UUID
 
 object LocalEcho {
 
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/DeviceListManager.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/DeviceListManager.kt
index 7f2a23e4c2..b2002f0916 100755
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/DeviceListManager.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/DeviceListManager.kt
@@ -66,7 +66,7 @@ internal class DeviceListManager @Inject constructor(private val cryptoStore: IM
         if (':' in userId) {
             try {
                 synchronized(notReadyToRetryHS) {
-                    res = !notReadyToRetryHS.contains(userId.substring(userId.lastIndexOf(":") + 1))
+                    res = !notReadyToRetryHS.contains(userId.substringAfterLast(':'))
                 }
             } catch (e: Exception) {
                 Timber.e(e, "## canRetryKeysDownload() failed")
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/OutgoingRoomKeyRequestManager.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/OutgoingRoomKeyRequestManager.kt
index 89a27c9463..86e8a1825c 100755
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/OutgoingRoomKeyRequestManager.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/OutgoingRoomKeyRequestManager.kt
@@ -216,7 +216,7 @@ internal class OutgoingRoomKeyRequestManager @Inject constructor(
         sendMessageToDevices(requestMessage, request.recipients, request.requestId, object : MatrixCallback<Unit> {
             private fun onDone(state: OutgoingRoomKeyRequest.RequestState) {
                 if (request.state !== OutgoingRoomKeyRequest.RequestState.UNSENT) {
-                    Timber.v("## sendOutgoingRoomKeyRequest() : Cannot update room key request from UNSENT as it was already updated to " + request.state)
+                    Timber.v("## sendOutgoingRoomKeyRequest() : Cannot update room key request from UNSENT as it was already updated to ${request.state}")
                 } else {
                     request.state = state
                     cryptoStore.updateOutgoingRoomKeyRequest(request)
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/verification/DefaultSasVerificationService.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/verification/DefaultSasVerificationService.kt
index ca1157e583..e0cd47e0e0 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/verification/DefaultSasVerificationService.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/verification/DefaultSasVerificationService.kt
@@ -43,6 +43,7 @@ import im.vector.matrix.android.internal.util.MatrixCoroutineDispatchers
 import kotlinx.coroutines.GlobalScope
 import kotlinx.coroutines.launch
 import timber.log.Timber
+import java.lang.Exception
 import java.util.UUID
 import javax.inject.Inject
 import kotlin.collections.HashMap
@@ -166,72 +167,59 @@ internal class DefaultSasVerificationService @Inject constructor(private val cre
             return
         }
         // Download device keys prior to everything
-        checkKeysAreDownloaded(
-                otherUserId!!,
-                startReq,
-                success = {
-                    Timber.v("## SAS onStartRequestReceived ${startReq.transactionID!!}")
-                    val tid = startReq.transactionID!!
-                    val existing = getExistingTransaction(otherUserId, tid)
-                    val existingTxs = getExistingTransactionsForUser(otherUserId)
-                    if (existing != null) {
-                        // should cancel both!
-                        Timber.v("## SAS onStartRequestReceived - Request exist with same if ${startReq.transactionID!!}")
-                        existing.cancel(CancelCode.UnexpectedMessage)
-                        cancelTransaction(tid, otherUserId, startReq.fromDevice!!, CancelCode.UnexpectedMessage)
-                    } else if (existingTxs?.isEmpty() == false) {
-                        Timber.v("## SAS onStartRequestReceived - There is already a transaction with this user ${startReq.transactionID!!}")
-                        // Multiple keyshares between two devices: any two devices may only have at most one key verification in flight at a time.
-                        existingTxs.forEach {
-                            it.cancel(CancelCode.UnexpectedMessage)
-                        }
-                        cancelTransaction(tid, otherUserId, startReq.fromDevice!!, CancelCode.UnexpectedMessage)
-                    } else {
-                        // Ok we can create
-                        if (KeyVerificationStart.VERIF_METHOD_SAS == startReq.method) {
-                            Timber.v("## SAS onStartRequestReceived - request accepted ${startReq.transactionID!!}")
-                            val tx = IncomingSASVerificationTransaction(
-                                    this,
-                                    setDeviceVerificationAction,
-                                    credentials,
-                                    cryptoStore,
-                                    sendToDeviceTask,
-                                    taskExecutor,
-                                    myDeviceInfoHolder.get().myDevice.fingerprint()!!,
-                                    startReq.transactionID!!,
-                                    otherUserId)
-                            addTransaction(tx)
-                            tx.acceptToDeviceEvent(otherUserId, startReq)
-                        } else {
-                            Timber.e("## SAS onStartRequestReceived - unknown method ${startReq.method}")
-                            cancelTransaction(tid, otherUserId, startReq.fromDevice
-                                    ?: event.getSenderKey()!!, CancelCode.UnknownMethod)
-                        }
-                    }
-                },
-                error = {
-                    cancelTransaction(startReq.transactionID!!, otherUserId, startReq.fromDevice!!, CancelCode.UnexpectedMessage)
-                })
+        if (checkKeysAreDownloaded(otherUserId!!, startReq) != null) {
+            Timber.v("## SAS onStartRequestReceived ${startReq.transactionID!!}")
+            val tid = startReq.transactionID!!
+            val existing = getExistingTransaction(otherUserId, tid)
+            val existingTxs = getExistingTransactionsForUser(otherUserId)
+            if (existing != null) {
+                // should cancel both!
+                Timber.v("## SAS onStartRequestReceived - Request exist with same if ${startReq.transactionID!!}")
+                existing.cancel(CancelCode.UnexpectedMessage)
+                cancelTransaction(tid, otherUserId, startReq.fromDevice!!, CancelCode.UnexpectedMessage)
+            } else if (existingTxs?.isEmpty() == false) {
+                Timber.v("## SAS onStartRequestReceived - There is already a transaction with this user ${startReq.transactionID!!}")
+                // Multiple keyshares between two devices: any two devices may only have at most one key verification in flight at a time.
+                existingTxs.forEach {
+                    it.cancel(CancelCode.UnexpectedMessage)
+                }
+                cancelTransaction(tid, otherUserId, startReq.fromDevice!!, CancelCode.UnexpectedMessage)
+            } else {
+                // Ok we can create
+                if (KeyVerificationStart.VERIF_METHOD_SAS == startReq.method) {
+                    Timber.v("## SAS onStartRequestReceived - request accepted ${startReq.transactionID!!}")
+                    val tx = IncomingSASVerificationTransaction(
+                            this,
+                            setDeviceVerificationAction,
+                            credentials,
+                            cryptoStore,
+                            sendToDeviceTask,
+                            taskExecutor,
+                            myDeviceInfoHolder.get().myDevice.fingerprint()!!,
+                            startReq.transactionID!!,
+                            otherUserId)
+                    addTransaction(tx)
+                    tx.acceptToDeviceEvent(otherUserId, startReq)
+                } else {
+                    Timber.e("## SAS onStartRequestReceived - unknown method ${startReq.method}")
+                    cancelTransaction(tid, otherUserId, startReq.fromDevice
+                            ?: event.getSenderKey()!!, CancelCode.UnknownMethod)
+                }
+            }
+        } else {
+            cancelTransaction(startReq.transactionID!!, otherUserId, startReq.fromDevice!!, CancelCode.UnexpectedMessage)
+        }
     }
 
     private suspend fun checkKeysAreDownloaded(otherUserId: String,
-                                               startReq: KeyVerificationStart,
-                                               success: (MXUsersDevicesMap<MXDeviceInfo>) -> Unit,
-                                               error: () -> Unit) {
-        runCatching {
-            deviceListManager.downloadKeys(listOf(otherUserId), true)
-        }.fold(
-                {
-                    if (it.getUserDeviceIds(otherUserId)?.contains(startReq.fromDevice) == true) {
-                        success(it)
-                    } else {
-                        error()
-                    }
-                },
-                {
-                    error()
-                }
-        )
+                                               startReq: KeyVerificationStart): MXUsersDevicesMap<MXDeviceInfo>? {
+        return try {
+            val keys = deviceListManager.downloadKeys(listOf(otherUserId), true)
+            val deviceIds = keys.getUserDeviceIds(otherUserId) ?: return null
+            keys.takeIf { deviceIds.contains(startReq.fromDevice) }
+        } catch (e: Exception) {
+            null
+        }
     }
 
     private suspend fun onCancelReceived(event: Event) {
@@ -342,10 +330,8 @@ internal class DefaultSasVerificationService @Inject constructor(private val cre
     private fun addTransaction(tx: VerificationTransaction) {
         tx.otherUserId.let { otherUserId ->
             synchronized(txMap) {
-                if (txMap[otherUserId] == null) {
-                    txMap[otherUserId] = HashMap()
-                }
-                txMap[otherUserId]?.set(tx.transactionId, tx)
+                val txInnerMap = txMap.getOrPut(otherUserId) { HashMap() }
+                txInnerMap[tx.transactionId] = tx
                 dispatchTxAdded(tx)
                 tx.addListener(this)
             }
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/database/mapper/RoomSummaryMapper.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/database/mapper/RoomSummaryMapper.kt
index 5db062b000..0d0143d318 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/database/mapper/RoomSummaryMapper.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/database/mapper/RoomSummaryMapper.kt
@@ -22,7 +22,7 @@ import im.vector.matrix.android.api.session.room.model.RoomSummary
 import im.vector.matrix.android.api.session.room.model.tag.RoomTag
 import im.vector.matrix.android.internal.crypto.algorithms.olm.OlmDecryptionResult
 import im.vector.matrix.android.internal.database.model.RoomSummaryEntity
-import java.util.*
+import java.util.UUID
 import javax.inject.Inject
 
 internal class RoomSummaryMapper @Inject constructor(
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/network/NetworkConnectivityChecker.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/network/NetworkConnectivityChecker.kt
index bfc37d733d..3d850c223a 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/network/NetworkConnectivityChecker.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/network/NetworkConnectivityChecker.kt
@@ -22,7 +22,7 @@ import com.novoda.merlin.MerlinsBeard
 import im.vector.matrix.android.internal.di.MatrixScope
 import im.vector.matrix.android.internal.util.BackgroundDetectionObserver
 import timber.log.Timber
-import java.util.*
+import java.util.Collections
 import javax.inject.Inject
 import kotlin.coroutines.resume
 import kotlin.coroutines.suspendCoroutine
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/homeserver/DefaultGetHomeServerCapabilitiesTask.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/homeserver/DefaultGetHomeServerCapabilitiesTask.kt
index 98ab0b5389..45571286b9 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/homeserver/DefaultGetHomeServerCapabilitiesTask.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/homeserver/DefaultGetHomeServerCapabilitiesTask.kt
@@ -23,7 +23,7 @@ import im.vector.matrix.android.internal.database.query.getOrCreate
 import im.vector.matrix.android.internal.network.executeRequest
 import im.vector.matrix.android.internal.task.Task
 import im.vector.matrix.android.internal.util.awaitTransaction
-import java.util.*
+import java.util.Date
 import javax.inject.Inject
 
 internal interface GetHomeServerCapabilitiesTask : Task<Unit, Unit>
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/pushers/DefaultPusherService.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/pushers/DefaultPusherService.kt
index 243e4d4b03..8c7e9fb263 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/pushers/DefaultPusherService.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/pushers/DefaultPusherService.kt
@@ -32,7 +32,7 @@ import im.vector.matrix.android.internal.task.configureWith
 import im.vector.matrix.android.internal.worker.WorkManagerUtil
 import im.vector.matrix.android.internal.worker.WorkManagerUtil.matrixOneTimeWorkRequestBuilder
 import im.vector.matrix.android.internal.worker.WorkerParamsFactory
-import java.util.*
+import java.util.UUID
 import java.util.concurrent.TimeUnit
 import javax.inject.Inject
 
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/send/LocalEchoEventFactory.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/send/LocalEchoEventFactory.kt
index 49c813ece6..a9406c8bff 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/send/LocalEchoEventFactory.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/send/LocalEchoEventFactory.kt
@@ -39,7 +39,7 @@ import im.vector.matrix.android.internal.session.room.RoomSummaryUpdater
 import im.vector.matrix.android.internal.util.StringProvider
 import org.commonmark.parser.Parser
 import org.commonmark.renderer.html.HtmlRenderer
-import java.util.*
+import java.util.UUID
 import javax.inject.Inject
 
 /**
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/timeline/DefaultTimeline.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/timeline/DefaultTimeline.kt
index 606c20e8cb..4127e43540 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/timeline/DefaultTimeline.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/timeline/DefaultTimeline.kt
@@ -52,7 +52,8 @@ import io.realm.RealmQuery
 import io.realm.RealmResults
 import io.realm.Sort
 import timber.log.Timber
-import java.util.*
+import java.util.Collections
+import java.util.UUID
 import java.util.concurrent.atomic.AtomicBoolean
 import java.util.concurrent.atomic.AtomicReference
 import kotlin.collections.ArrayList
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/securestorage/SecretStoringUtils.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/securestorage/SecretStoringUtils.kt
index 260f98d97f..592191975e 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/securestorage/SecretStoringUtils.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/securestorage/SecretStoringUtils.kt
@@ -31,7 +31,7 @@ import java.security.KeyPairGenerator
 import java.security.KeyStore
 import java.security.KeyStoreException
 import java.security.SecureRandom
-import java.util.*
+import java.util.Calendar
 import javax.crypto.*
 import javax.crypto.spec.GCMParameterSpec
 import javax.crypto.spec.IvParameterSpec
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/util/CompatUtil.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/util/CompatUtil.kt
index 058a862bc8..2df2bd2bf2 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/util/CompatUtil.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/util/CompatUtil.kt
@@ -36,7 +36,7 @@ import java.security.*
 import java.security.cert.CertificateException
 import java.security.spec.AlgorithmParameterSpec
 import java.security.spec.RSAKeyGenParameterSpec
-import java.util.*
+import java.util.Calendar
 import java.util.zip.GZIPOutputStream
 import javax.crypto.*
 import javax.crypto.spec.GCMParameterSpec
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/util/StringUtils.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/util/StringUtils.kt
index 4a46a43f03..31da372bbe 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/util/StringUtils.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/util/StringUtils.kt
@@ -18,7 +18,7 @@ package im.vector.matrix.android.internal.util
 
 import im.vector.matrix.android.api.MatrixPatterns
 import timber.log.Timber
-import java.util.*
+import java.util.Locale
 
 /**
  * Convert a string to an UTF8 String
diff --git a/vector/src/main/java/im/vector/riotx/VectorApplication.kt b/vector/src/main/java/im/vector/riotx/VectorApplication.kt
index b1fd6a8485..20a17e55d4 100644
--- a/vector/src/main/java/im/vector/riotx/VectorApplication.kt
+++ b/vector/src/main/java/im/vector/riotx/VectorApplication.kt
@@ -55,7 +55,8 @@ import im.vector.riotx.features.version.VersionProvider
 import im.vector.riotx.push.fcm.FcmHelper
 import timber.log.Timber
 import java.text.SimpleDateFormat
-import java.util.*
+import java.util.Date
+import java.util.Locale
 import javax.inject.Inject
 
 class VectorApplication : Application(), HasVectorInjector, MatrixConfiguration.Provider, androidx.work.Configuration.Provider {
diff --git a/vector/src/main/java/im/vector/riotx/core/files/FileSaver.kt b/vector/src/main/java/im/vector/riotx/core/files/FileSaver.kt
index c1f58306a4..677f7894e8 100644
--- a/vector/src/main/java/im/vector/riotx/core/files/FileSaver.kt
+++ b/vector/src/main/java/im/vector/riotx/core/files/FileSaver.kt
@@ -30,15 +30,10 @@ import java.io.File
  */
 @WorkerThread
 fun writeToFile(str: String, file: File): Try<Unit> {
-    return Try {
-        val sink = file.sink()
-
-        val bufferedSink = sink.buffer()
-
-        bufferedSink.writeString(str, Charsets.UTF_8)
-
-        bufferedSink.close()
-        sink.close()
+    return Try<Unit> {
+        file.sink().buffer().use {
+            it.writeString(str, Charsets.UTF_8)
+        }
     }
 }
 
@@ -47,15 +42,10 @@ fun writeToFile(str: String, file: File): Try<Unit> {
  */
 @WorkerThread
 fun writeToFile(data: ByteArray, file: File): Try<Unit> {
-    return Try {
-        val sink = file.sink()
-
-        val bufferedSink = sink.buffer()
-
-        bufferedSink.write(data)
-
-        bufferedSink.close()
-        sink.close()
+    return Try<Unit> {
+        file.sink().buffer().use {
+            it.write(data)
+        }
     }
 }
 
diff --git a/vector/src/main/java/im/vector/riotx/core/images/ImageTools.kt b/vector/src/main/java/im/vector/riotx/core/images/ImageTools.kt
index b6ae2be20b..84cba7392f 100644
--- a/vector/src/main/java/im/vector/riotx/core/images/ImageTools.kt
+++ b/vector/src/main/java/im/vector/riotx/core/images/ImageTools.kt
@@ -17,7 +17,6 @@
 package im.vector.riotx.core.images
 
 import android.content.Context
-import android.database.Cursor
 import android.net.Uri
 import android.provider.MediaStore
 import androidx.exifinterface.media.ExifInterface
@@ -37,26 +36,24 @@ class ImageTools @Inject constructor(private val context: Context) {
 
         if (uri.scheme == "content") {
             val proj = arrayOf(MediaStore.Images.Media.DATA)
-            var cursor: Cursor? = null
             try {
-                cursor = context.contentResolver.query(uri, proj, null, null, null)
-                if (cursor != null && cursor.count > 0) {
-                    cursor.moveToFirst()
-                    val idxData = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA)
-                    val path = cursor.getString(idxData)
-                    if (path.isNullOrBlank()) {
-                        Timber.w("Cannot find path in media db for uri $uri")
-                        return orientation
+                val cursor = context.contentResolver.query(uri, proj, null, null, null)
+                cursor?.use {
+                    if (it.moveToFirst()) {
+                        val idxData = it.getColumnIndexOrThrow(MediaStore.Images.Media.DATA)
+                        val path = it.getString(idxData)
+                        if (path.isNullOrBlank()) {
+                            Timber.w("Cannot find path in media db for uri $uri")
+                            return orientation
+                        }
+                        val exif = ExifInterface(path)
+                        orientation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION, ExifInterface.ORIENTATION_UNDEFINED)
                     }
-                    val exif = ExifInterface(path)
-                    orientation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION, ExifInterface.ORIENTATION_UNDEFINED)
                 }
             } catch (e: Exception) {
                 // eg SecurityException from com.google.android.apps.photos.content.GooglePhotosImageProvider URIs
                 // eg IOException from trying to parse the returned path as a file when it is an http uri.
                 Timber.e(e, "Cannot get orientation for bitmap")
-            } finally {
-                cursor?.close()
             }
         } else if (uri.scheme == "file") {
             try {
diff --git a/vector/src/main/java/im/vector/riotx/core/intent/Filename.kt b/vector/src/main/java/im/vector/riotx/core/intent/Filename.kt
index 9e9f0ae508..2b6740f62f 100644
--- a/vector/src/main/java/im/vector/riotx/core/intent/Filename.kt
+++ b/vector/src/main/java/im/vector/riotx/core/intent/Filename.kt
@@ -17,28 +17,17 @@
 package im.vector.riotx.core.intent
 
 import android.content.Context
-import android.database.Cursor
 import android.net.Uri
 import android.provider.OpenableColumns
 
 fun getFilenameFromUri(context: Context?, uri: Uri): String? {
-    var result: String? = null
     if (context != null && uri.scheme == "content") {
-        val cursor: Cursor? = context.contentResolver.query(uri, null, null, null, null)
-        try {
-            if (cursor != null && cursor.moveToFirst()) {
-                result = cursor.getString(cursor.getColumnIndex(OpenableColumns.DISPLAY_NAME))
+        val cursor = context.contentResolver.query(uri, null, null, null, null)
+        cursor?.use {
+            if (it.moveToFirst()) {
+                return it.getString(it.getColumnIndex(OpenableColumns.DISPLAY_NAME))
             }
-        } finally {
-            cursor?.close()
         }
     }
-    if (result == null) {
-        result = uri.path
-        val cut = result?.lastIndexOf('/') ?: -1
-        if (cut != -1) {
-            result = result?.substring(cut + 1)
-        }
-    }
-    return result
+    return uri.path?.substringAfterLast('/')
 }
diff --git a/vector/src/main/java/im/vector/riotx/core/linkify/VectorAutoLinkPatterns.kt b/vector/src/main/java/im/vector/riotx/core/linkify/VectorAutoLinkPatterns.kt
index e6eb886e02..ae4131b5e9 100644
--- a/vector/src/main/java/im/vector/riotx/core/linkify/VectorAutoLinkPatterns.kt
+++ b/vector/src/main/java/im/vector/riotx/core/linkify/VectorAutoLinkPatterns.kt
@@ -15,8 +15,6 @@
  */
 package im.vector.riotx.core.linkify
 
-import java.util.regex.Pattern
-
 /**
  * Better support for geo URi
  */
@@ -26,7 +24,7 @@ object VectorAutoLinkPatterns {
     private const val LAT_OR_LONG_OR_ALT_NUMBER = "-?\\d+(?:\\.\\d+)?"
     private const val COORDINATE_SYSTEM = ";crs=[\\w-]+"
 
-    val GEO_URI: Pattern = Pattern.compile("(?:geo:)?" +
+    val GEO_URI: Regex = Regex("(?:geo:)?" +
             "(" + LAT_OR_LONG_OR_ALT_NUMBER + ")" +
             "," +
             "(" + LAT_OR_LONG_OR_ALT_NUMBER + ")" +
@@ -35,5 +33,5 @@ object VectorAutoLinkPatterns {
             "(?:" + ";u=\\d+(?:\\.\\d+)?" + ")?" + // uncertainty in meters
             "(?:" +
             ";[\\w-]+=(?:[\\w-_.!~*'()]|%[\\da-f][\\da-f])+" + // dafuk
-            ")*", Pattern.CASE_INSENSITIVE)
+            ")*", RegexOption.IGNORE_CASE)
 }
diff --git a/vector/src/main/java/im/vector/riotx/core/linkify/VectorLinkify.kt b/vector/src/main/java/im/vector/riotx/core/linkify/VectorLinkify.kt
index 358fff6092..99b0316cbe 100644
--- a/vector/src/main/java/im/vector/riotx/core/linkify/VectorLinkify.kt
+++ b/vector/src/main/java/im/vector/riotx/core/linkify/VectorLinkify.kt
@@ -19,7 +19,6 @@ import android.text.Spannable
 import android.text.style.URLSpan
 import android.text.util.Linkify
 import androidx.core.text.util.LinkifyCompat
-import java.util.*
 
 object VectorLinkify {
     /**
@@ -95,7 +94,7 @@ object VectorLinkify {
             createdSpans.add(LinkSpec(URLSpan(urlSpan.url), start, end))
         }
 
-        LinkifyCompat.addLinks(spannable, VectorAutoLinkPatterns.GEO_URI, "geo:", arrayOf("geo:"), geoMatchFilter, null)
+        LinkifyCompat.addLinks(spannable, VectorAutoLinkPatterns.GEO_URI.toPattern(), "geo:", arrayOf("geo:"), geoMatchFilter, null)
         spannable.forEachSpanIndexed { _, urlSpan, start, end ->
             spannable.removeSpan(urlSpan)
             createdSpans.add(LinkSpec(URLSpan(urlSpan.url), start, end))
@@ -108,7 +107,7 @@ object VectorLinkify {
     }
 
     private fun pruneOverlaps(links: ArrayList<LinkSpec>) {
-        Collections.sort(links, COMPARATOR)
+        links.sortWith(COMPARATOR)
         var len = links.size
         var i = 0
         while (i < len - 1) {
diff --git a/vector/src/main/java/im/vector/riotx/core/platform/VectorBaseBottomSheetDialogFragment.kt b/vector/src/main/java/im/vector/riotx/core/platform/VectorBaseBottomSheetDialogFragment.kt
index 8d40d55a7a..1b07d739b5 100644
--- a/vector/src/main/java/im/vector/riotx/core/platform/VectorBaseBottomSheetDialogFragment.kt
+++ b/vector/src/main/java/im/vector/riotx/core/platform/VectorBaseBottomSheetDialogFragment.kt
@@ -30,7 +30,7 @@ import com.google.android.material.bottomsheet.BottomSheetDialogFragment
 import im.vector.riotx.core.di.DaggerScreenComponent
 import im.vector.riotx.core.di.ScreenComponent
 import im.vector.riotx.core.utils.DimensionConverter
-import java.util.*
+import java.util.UUID
 
 /**
  * Add MvRx capabilities to bottomsheetdialog (like BaseMvRxFragment)
diff --git a/vector/src/main/java/im/vector/riotx/core/pushers/PushersManager.kt b/vector/src/main/java/im/vector/riotx/core/pushers/PushersManager.kt
index 41287d4e38..e2c08a1fe8 100644
--- a/vector/src/main/java/im/vector/riotx/core/pushers/PushersManager.kt
+++ b/vector/src/main/java/im/vector/riotx/core/pushers/PushersManager.kt
@@ -22,8 +22,9 @@ import im.vector.riotx.core.di.ActiveSessionHolder
 import im.vector.riotx.core.resources.AppNameProvider
 import im.vector.riotx.core.resources.LocaleProvider
 import im.vector.riotx.core.resources.StringProvider
-import java.util.*
+import java.util.UUID
 import javax.inject.Inject
+import kotlin.math.abs
 
 private const val DEFAULT_PUSHER_FILE_TAG = "mobile"
 
@@ -36,7 +37,7 @@ class PushersManager @Inject constructor(
 
     fun registerPusherWithFcmKey(pushKey: String): UUID {
         val currentSession = activeSessionHolder.getActiveSession()
-        var profileTag = DEFAULT_PUSHER_FILE_TAG + "_" + Math.abs(currentSession.myUserId.hashCode())
+        val profileTag = DEFAULT_PUSHER_FILE_TAG + "_" + abs(currentSession.myUserId.hashCode())
 
         return currentSession.addHttpPusher(
                 pushKey,
diff --git a/vector/src/main/java/im/vector/riotx/core/resources/LocaleProvider.kt b/vector/src/main/java/im/vector/riotx/core/resources/LocaleProvider.kt
index 74861a65cc..c78a5a99b8 100644
--- a/vector/src/main/java/im/vector/riotx/core/resources/LocaleProvider.kt
+++ b/vector/src/main/java/im/vector/riotx/core/resources/LocaleProvider.kt
@@ -18,7 +18,7 @@ package im.vector.riotx.core.resources
 
 import android.content.res.Resources
 import androidx.core.os.ConfigurationCompat
-import java.util.*
+import java.util.Locale
 import javax.inject.Inject
 
 class LocaleProvider @Inject constructor(private val resources: Resources) {
diff --git a/vector/src/main/java/im/vector/riotx/core/utils/DebouncedClickListener.kt b/vector/src/main/java/im/vector/riotx/core/utils/DebouncedClickListener.kt
index 958f642565..230b11f14d 100644
--- a/vector/src/main/java/im/vector/riotx/core/utils/DebouncedClickListener.kt
+++ b/vector/src/main/java/im/vector/riotx/core/utils/DebouncedClickListener.kt
@@ -16,7 +16,7 @@
 package im.vector.riotx.core.utils
 
 import android.view.View
-import java.util.*
+import java.util.WeakHashMap
 
 /**
  * Simple Debounced OnClickListener
diff --git a/vector/src/main/java/im/vector/riotx/core/utils/Emoji.kt b/vector/src/main/java/im/vector/riotx/core/utils/Emoji.kt
index c65fcafb16..a5babcc885 100644
--- a/vector/src/main/java/im/vector/riotx/core/utils/Emoji.kt
+++ b/vector/src/main/java/im/vector/riotx/core/utils/Emoji.kt
@@ -59,9 +59,10 @@ fun initKnownEmojiHashSet(context: Context, done: (() -> Unit)? = null) {
             val jsonAdapter = moshi.adapter(EmojiDataSource.EmojiData::class.java)
             val inputAsString = input.bufferedReader().use { it.readText() }
             val source = jsonAdapter.fromJson(inputAsString)
-            knownEmojiSet = HashSet<String>()
-            source?.emojis?.values?.forEach {
-                knownEmojiSet?.add(it.emojiString())
+            knownEmojiSet = HashSet<String>().also {
+                source?.emojis?.mapTo(it) { (_, value) ->
+                    value.emojiString()
+                }
             }
             done?.invoke()
         }
diff --git a/vector/src/main/java/im/vector/riotx/core/utils/ExternalApplicationsUtil.kt b/vector/src/main/java/im/vector/riotx/core/utils/ExternalApplicationsUtil.kt
index 9572b07216..78242d58de 100644
--- a/vector/src/main/java/im/vector/riotx/core/utils/ExternalApplicationsUtil.kt
+++ b/vector/src/main/java/im/vector/riotx/core/utils/ExternalApplicationsUtil.kt
@@ -32,7 +32,8 @@ import im.vector.riotx.R
 import timber.log.Timber
 import java.io.File
 import java.text.SimpleDateFormat
-import java.util.*
+import java.util.Date
+import java.util.Locale
 
 /**
  * Open a url in the internet browser of the system
diff --git a/vector/src/main/java/im/vector/riotx/core/utils/SystemUtils.kt b/vector/src/main/java/im/vector/riotx/core/utils/SystemUtils.kt
index 12371fe72d..ba0b99762b 100644
--- a/vector/src/main/java/im/vector/riotx/core/utils/SystemUtils.kt
+++ b/vector/src/main/java/im/vector/riotx/core/utils/SystemUtils.kt
@@ -31,7 +31,7 @@ import im.vector.riotx.R
 import im.vector.riotx.features.notifications.NotificationUtils
 import im.vector.riotx.features.settings.VectorLocale
 import timber.log.Timber
-import java.util.*
+import java.util.Locale
 
 /**
  * Tells if the application ignores battery optimizations.
diff --git a/vector/src/main/java/im/vector/riotx/core/utils/TextUtils.kt b/vector/src/main/java/im/vector/riotx/core/utils/TextUtils.kt
index 0b5df0d2e0..75f6893c7c 100644
--- a/vector/src/main/java/im/vector/riotx/core/utils/TextUtils.kt
+++ b/vector/src/main/java/im/vector/riotx/core/utils/TextUtils.kt
@@ -19,7 +19,7 @@ package im.vector.riotx.core.utils
 import android.content.Context
 import android.os.Build
 import android.text.format.Formatter
-import java.util.*
+import java.util.TreeMap
 
 object TextUtils {
 
diff --git a/vector/src/main/java/im/vector/riotx/features/configuration/VectorConfiguration.kt b/vector/src/main/java/im/vector/riotx/features/configuration/VectorConfiguration.kt
index ec8f1c7fa2..adf8421842 100644
--- a/vector/src/main/java/im/vector/riotx/features/configuration/VectorConfiguration.kt
+++ b/vector/src/main/java/im/vector/riotx/features/configuration/VectorConfiguration.kt
@@ -24,7 +24,7 @@ import im.vector.riotx.features.settings.FontScale
 import im.vector.riotx.features.settings.VectorLocale
 import im.vector.riotx.features.themes.ThemeUtils
 import timber.log.Timber
-import java.util.*
+import java.util.Locale
 import javax.inject.Inject
 
 /**
diff --git a/vector/src/main/java/im/vector/riotx/features/crypto/keys/KeysExporter.kt b/vector/src/main/java/im/vector/riotx/features/crypto/keys/KeysExporter.kt
index 54e3a34744..9642c2d8c6 100644
--- a/vector/src/main/java/im/vector/riotx/features/crypto/keys/KeysExporter.kt
+++ b/vector/src/main/java/im/vector/riotx/features/crypto/keys/KeysExporter.kt
@@ -18,10 +18,10 @@ package im.vector.riotx.features.crypto.keys
 
 import android.content.Context
 import android.os.Environment
-import arrow.core.Try
 import im.vector.matrix.android.api.MatrixCallback
 import im.vector.matrix.android.api.session.Session
 import im.vector.matrix.android.internal.extensions.foldToCallback
+import im.vector.matrix.android.internal.util.awaitCallback
 import im.vector.riotx.core.files.addEntryToDownloadManager
 import im.vector.riotx.core.files.writeToFile
 import kotlinx.coroutines.Dispatchers
@@ -36,28 +36,20 @@ class KeysExporter(private val session: Session) {
      * Export keys and return the file path with the callback
      */
     fun export(context: Context, password: String, callback: MatrixCallback<String>) {
-        session.exportRoomKeys(password, object : MatrixCallback<ByteArray> {
-            override fun onSuccess(data: ByteArray) {
-                GlobalScope.launch(Dispatchers.Main) {
-                    withContext(Dispatchers.IO) {
-                        Try {
-                            val parentDir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS)
-                            val file = File(parentDir, "riotx-keys-" + System.currentTimeMillis() + ".txt")
+        GlobalScope.launch(Dispatchers.Main) {
+            runCatching {
+                val data = awaitCallback<ByteArray> { session.exportRoomKeys(password, it) }
+                withContext(Dispatchers.IO) {
+                    val parentDir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS)
+                    val file = File(parentDir, "riotx-keys-" + System.currentTimeMillis() + ".txt")
 
-                            writeToFile(data, file)
+                    writeToFile(data, file)
 
-                            addEntryToDownloadManager(context, file, "text/plain")
+                    addEntryToDownloadManager(context, file, "text/plain")
 
-                            file.absolutePath
-                        }
-                    }
-                            .foldToCallback(callback)
+                    file.absolutePath
                 }
-            }
-
-            override fun onFailure(failure: Throwable) {
-                callback.onFailure(failure)
-            }
-        })
+            }.foldToCallback(callback)
+        }
     }
 }
diff --git a/vector/src/main/java/im/vector/riotx/features/crypto/keys/KeysImporter.kt b/vector/src/main/java/im/vector/riotx/features/crypto/keys/KeysImporter.kt
index 74b2a86bc1..b60e25af04 100644
--- a/vector/src/main/java/im/vector/riotx/features/crypto/keys/KeysImporter.kt
+++ b/vector/src/main/java/im/vector/riotx/features/crypto/keys/KeysImporter.kt
@@ -18,10 +18,11 @@ package im.vector.riotx.features.crypto.keys
 
 import android.content.Context
 import android.net.Uri
-import arrow.core.Try
 import im.vector.matrix.android.api.MatrixCallback
 import im.vector.matrix.android.api.session.Session
 import im.vector.matrix.android.internal.crypto.model.ImportRoomKeysResult
+import im.vector.matrix.android.internal.extensions.foldToCallback
+import im.vector.matrix.android.internal.util.awaitCallback
 import im.vector.riotx.core.intent.getMimeTypeFromUri
 import im.vector.riotx.core.resources.openResource
 import kotlinx.coroutines.Dispatchers
@@ -41,8 +42,8 @@ class KeysImporter(private val session: Session) {
                password: String,
                callback: MatrixCallback<ImportRoomKeysResult>) {
         GlobalScope.launch(Dispatchers.Main) {
-            withContext(Dispatchers.IO) {
-                Try {
+            runCatching {
+                withContext(Dispatchers.IO) {
                     val resource = openResource(context, uri, mimetype ?: getMimeTypeFromUri(context, uri))
 
                     if (resource?.mContentStream == null) {
@@ -51,33 +52,17 @@ class KeysImporter(private val session: Session) {
 
                     val data: ByteArray
                     try {
-                        data = ByteArray(resource.mContentStream!!.available())
-                        resource.mContentStream!!.read(data)
-                        resource.mContentStream!!.close()
-
-                        data
+                        data = resource.mContentStream!!.use { it.readBytes() }
                     } catch (e: Exception) {
-                        try {
-                            resource.mContentStream!!.close()
-                        } catch (e2: Exception) {
-                            Timber.e(e2, "## importKeys()")
-                        }
-
+                        Timber.e(e, "## importKeys()")
                         throw e
                     }
+
+                    awaitCallback<ImportRoomKeysResult> {
+                        session.importRoomKeys(data, password, null, it)
+                    }
                 }
-            }
-                    .fold(
-                            {
-                                callback.onFailure(it)
-                            },
-                            { byteArray ->
-                                session.importRoomKeys(byteArray,
-                                        password,
-                                        null,
-                                        callback)
-                            }
-                    )
+            }.foldToCallback(callback)
         }
     }
 }
diff --git a/vector/src/main/java/im/vector/riotx/features/crypto/keysbackup/settings/KeysBackupSettingsRecyclerViewController.kt b/vector/src/main/java/im/vector/riotx/features/crypto/keysbackup/settings/KeysBackupSettingsRecyclerViewController.kt
index 6b01a7dffa..7b60cb2f9b 100644
--- a/vector/src/main/java/im/vector/riotx/features/crypto/keysbackup/settings/KeysBackupSettingsRecyclerViewController.kt
+++ b/vector/src/main/java/im/vector/riotx/features/crypto/keysbackup/settings/KeysBackupSettingsRecyclerViewController.kt
@@ -31,7 +31,7 @@ import im.vector.riotx.core.epoxy.loadingItem
 import im.vector.riotx.core.resources.StringProvider
 import im.vector.riotx.core.ui.list.GenericItem
 import im.vector.riotx.core.ui.list.genericItem
-import java.util.*
+import java.util.UUID
 import javax.inject.Inject
 
 class KeysBackupSettingsRecyclerViewController @Inject constructor(private val stringProvider: StringProvider,
diff --git a/vector/src/main/java/im/vector/riotx/features/crypto/keysbackup/setup/KeysBackupSetupStep3Fragment.kt b/vector/src/main/java/im/vector/riotx/features/crypto/keysbackup/setup/KeysBackupSetupStep3Fragment.kt
index 7b61ca2c0f..a5cc0510da 100644
--- a/vector/src/main/java/im/vector/riotx/features/crypto/keysbackup/setup/KeysBackupSetupStep3Fragment.kt
+++ b/vector/src/main/java/im/vector/riotx/features/crypto/keysbackup/setup/KeysBackupSetupStep3Fragment.kt
@@ -170,8 +170,8 @@ class KeysBackupSetupStep3Fragment : VectorBaseFragment() {
 
     private fun exportRecoveryKeyToFile(data: String) {
         GlobalScope.launch(Dispatchers.Main) {
-            withContext(Dispatchers.IO) {
-                Try {
+            Try {
+                withContext(Dispatchers.IO) {
                     val parentDir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS)
                     val file = File(parentDir, "recovery-key-" + System.currentTimeMillis() + ".txt")
 
diff --git a/vector/src/main/java/im/vector/riotx/features/home/room/detail/timeline/action/MessageActionsViewModel.kt b/vector/src/main/java/im/vector/riotx/features/home/room/detail/timeline/action/MessageActionsViewModel.kt
index 135496264d..63a4919763 100644
--- a/vector/src/main/java/im/vector/riotx/features/home/room/detail/timeline/action/MessageActionsViewModel.kt
+++ b/vector/src/main/java/im/vector/riotx/features/home/room/detail/timeline/action/MessageActionsViewModel.kt
@@ -42,7 +42,8 @@ import im.vector.riotx.features.home.room.detail.timeline.format.NoticeEventForm
 import im.vector.riotx.features.home.room.detail.timeline.item.MessageInformationData
 import im.vector.riotx.features.html.EventHtmlRenderer
 import java.text.SimpleDateFormat
-import java.util.*
+import java.util.Date
+import java.util.Locale
 
 /**
  * Quick reactions state
diff --git a/vector/src/main/java/im/vector/riotx/features/home/room/detail/timeline/edithistory/ViewEditHistoryEpoxyController.kt b/vector/src/main/java/im/vector/riotx/features/home/room/detail/timeline/edithistory/ViewEditHistoryEpoxyController.kt
index d36e98f67c..4661d8f8cd 100644
--- a/vector/src/main/java/im/vector/riotx/features/home/room/detail/timeline/edithistory/ViewEditHistoryEpoxyController.kt
+++ b/vector/src/main/java/im/vector/riotx/features/home/room/detail/timeline/edithistory/ViewEditHistoryEpoxyController.kt
@@ -38,7 +38,7 @@ import im.vector.riotx.features.html.EventHtmlRenderer
 import me.gujun.android.span.span
 import name.fraser.neil.plaintext.diff_match_patch
 import timber.log.Timber
-import java.util.*
+import java.util.Calendar
 
 /**
  * Epoxy controller for edit history list
@@ -94,7 +94,7 @@ class ViewEditHistoryEpoxyController(private val context: Context,
                 val body = cContent.second?.let { eventHtmlRenderer.render(it) }
                         ?: cContent.first
 
-                val nextEvent = if (index + 1 <= sourceEvents.lastIndex) sourceEvents[index + 1] else null
+                val nextEvent = sourceEvents.getOrNull(index + 1)
 
                 var spannedDiff: Spannable? = null
                 if (nextEvent != null && cContent.second == null /*No diff for html*/) {
diff --git a/vector/src/main/java/im/vector/riotx/features/home/room/detail/timeline/edithistory/ViewEditHistoryViewModel.kt b/vector/src/main/java/im/vector/riotx/features/home/room/detail/timeline/edithistory/ViewEditHistoryViewModel.kt
index e2b976b273..93e7709b55 100644
--- a/vector/src/main/java/im/vector/riotx/features/home/room/detail/timeline/edithistory/ViewEditHistoryViewModel.kt
+++ b/vector/src/main/java/im/vector/riotx/features/home/room/detail/timeline/edithistory/ViewEditHistoryViewModel.kt
@@ -30,7 +30,7 @@ import im.vector.riotx.core.platform.VectorViewModel
 import im.vector.riotx.core.date.VectorDateFormatter
 import im.vector.riotx.features.home.room.detail.timeline.action.TimelineEventFragmentArgs
 import timber.log.Timber
-import java.util.*
+import java.util.UUID
 
 data class ViewEditHistoryViewState(
         val eventId: String,
diff --git a/vector/src/main/java/im/vector/riotx/features/notifications/NotifiableEventResolver.kt b/vector/src/main/java/im/vector/riotx/features/notifications/NotifiableEventResolver.kt
index 06108e07fe..786fabfca2 100644
--- a/vector/src/main/java/im/vector/riotx/features/notifications/NotifiableEventResolver.kt
+++ b/vector/src/main/java/im/vector/riotx/features/notifications/NotifiableEventResolver.kt
@@ -33,7 +33,7 @@ import im.vector.riotx.R
 import im.vector.riotx.core.resources.StringProvider
 import im.vector.riotx.features.home.room.detail.timeline.format.NoticeEventFormatter
 import timber.log.Timber
-import java.util.*
+import java.util.UUID
 import javax.inject.Inject
 
 /**
diff --git a/vector/src/main/java/im/vector/riotx/features/notifications/NotificationBroadcastReceiver.kt b/vector/src/main/java/im/vector/riotx/features/notifications/NotificationBroadcastReceiver.kt
index e26395641d..63cd1c5ce6 100644
--- a/vector/src/main/java/im/vector/riotx/features/notifications/NotificationBroadcastReceiver.kt
+++ b/vector/src/main/java/im/vector/riotx/features/notifications/NotificationBroadcastReceiver.kt
@@ -27,7 +27,7 @@ import im.vector.riotx.R
 import im.vector.riotx.core.di.ActiveSessionHolder
 import im.vector.riotx.core.extensions.vectorComponent
 import timber.log.Timber
-import java.util.*
+import java.util.UUID
 import javax.inject.Inject
 
 /**
diff --git a/vector/src/main/java/im/vector/riotx/features/notifications/NotificationUtils.kt b/vector/src/main/java/im/vector/riotx/features/notifications/NotificationUtils.kt
index 1a5385663b..7d8e43d0be 100755
--- a/vector/src/main/java/im/vector/riotx/features/notifications/NotificationUtils.kt
+++ b/vector/src/main/java/im/vector/riotx/features/notifications/NotificationUtils.kt
@@ -45,9 +45,9 @@ import im.vector.riotx.features.home.room.detail.RoomDetailActivity
 import im.vector.riotx.features.home.room.detail.RoomDetailArgs
 import im.vector.riotx.features.settings.VectorPreferences
 import timber.log.Timber
-import java.util.*
 import javax.inject.Inject
 import javax.inject.Singleton
+import kotlin.random.Random
 
 /**
  * Util class for creating notifications.
@@ -299,7 +299,7 @@ class NotificationUtils @Inject constructor(private val context: Context,
         // use a generator for the private requestCode.
         // When using 0, the intent is not created/launched when the user taps on the notification.
         //
-        val pendingIntent = stackBuilder.getPendingIntent(Random().nextInt(1000), PendingIntent.FLAG_UPDATE_CURRENT)
+        val pendingIntent = stackBuilder.getPendingIntent(Random.nextInt(1000), PendingIntent.FLAG_UPDATE_CURRENT)
 
         builder.setContentIntent(pendingIntent)
 
@@ -599,7 +599,7 @@ class NotificationUtils @Inject constructor(private val context: Context,
         val intent = HomeActivity.newIntent(context, clearNotification = true)
         intent.flags = Intent.FLAG_ACTIVITY_CLEAR_TOP or Intent.FLAG_ACTIVITY_SINGLE_TOP
         intent.data = Uri.parse("foobar://tapSummary")
-        return PendingIntent.getActivity(context, Random().nextInt(1000), intent, PendingIntent.FLAG_UPDATE_CURRENT)
+        return PendingIntent.getActivity(context, Random.nextInt(1000), intent, PendingIntent.FLAG_UPDATE_CURRENT)
     }
 
     /*
diff --git a/vector/src/main/java/im/vector/riotx/features/rageshake/BugReporter.kt b/vector/src/main/java/im/vector/riotx/features/rageshake/BugReporter.kt
index 9a7707d063..b96542a8ce 100755
--- a/vector/src/main/java/im/vector/riotx/features/rageshake/BugReporter.kt
+++ b/vector/src/main/java/im/vector/riotx/features/rageshake/BugReporter.kt
@@ -46,7 +46,7 @@ import org.json.JSONObject
 import timber.log.Timber
 import java.io.*
 import java.net.HttpURLConnection
-import java.util.*
+import java.util.Locale
 import java.util.zip.GZIPOutputStream
 import javax.inject.Inject
 import javax.inject.Singleton
diff --git a/vector/src/main/java/im/vector/riotx/features/rageshake/VectorFileLogger.kt b/vector/src/main/java/im/vector/riotx/features/rageshake/VectorFileLogger.kt
index 0b9cb5798c..95053790c8 100644
--- a/vector/src/main/java/im/vector/riotx/features/rageshake/VectorFileLogger.kt
+++ b/vector/src/main/java/im/vector/riotx/features/rageshake/VectorFileLogger.kt
@@ -24,7 +24,9 @@ import java.io.File
 import java.io.PrintWriter
 import java.io.StringWriter
 import java.text.SimpleDateFormat
-import java.util.*
+import java.util.Date
+import java.util.Locale
+import java.util.TimeZone
 import java.util.logging.*
 import java.util.logging.Formatter
 import javax.inject.Inject
diff --git a/vector/src/main/java/im/vector/riotx/features/settings/VectorSettingsGeneralFragment.kt b/vector/src/main/java/im/vector/riotx/features/settings/VectorSettingsGeneralFragment.kt
index 331b6e935a..ff76c61754 100644
--- a/vector/src/main/java/im/vector/riotx/features/settings/VectorSettingsGeneralFragment.kt
+++ b/vector/src/main/java/im/vector/riotx/features/settings/VectorSettingsGeneralFragment.kt
@@ -51,7 +51,6 @@ import kotlinx.coroutines.GlobalScope
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
 import java.io.File
-import java.util.*
 
 class VectorSettingsGeneralFragment : VectorSettingsBaseFragment() {
 
diff --git a/vector/src/main/java/im/vector/riotx/features/settings/VectorSettingsSecurityPrivacyFragment.kt b/vector/src/main/java/im/vector/riotx/features/settings/VectorSettingsSecurityPrivacyFragment.kt
index 2f52cdef13..a78529f06c 100644
--- a/vector/src/main/java/im/vector/riotx/features/settings/VectorSettingsSecurityPrivacyFragment.kt
+++ b/vector/src/main/java/im/vector/riotx/features/settings/VectorSettingsSecurityPrivacyFragment.kt
@@ -56,7 +56,8 @@ import im.vector.riotx.features.crypto.keysbackup.settings.KeysBackupManageActiv
 import timber.log.Timber
 import java.text.DateFormat
 import java.text.SimpleDateFormat
-import java.util.*
+import java.util.Date
+import java.util.Locale
 import javax.inject.Inject
 
 class VectorSettingsSecurityPrivacyFragment : VectorSettingsBaseFragment() {
diff --git a/vector/src/main/java/im/vector/riotx/features/themes/ThemeUtils.kt b/vector/src/main/java/im/vector/riotx/features/themes/ThemeUtils.kt
index 2edb59104b..40a14b3e6f 100644
--- a/vector/src/main/java/im/vector/riotx/features/themes/ThemeUtils.kt
+++ b/vector/src/main/java/im/vector/riotx/features/themes/ThemeUtils.kt
@@ -28,7 +28,6 @@ import androidx.core.graphics.drawable.DrawableCompat
 import androidx.preference.PreferenceManager
 import im.vector.riotx.R
 import timber.log.Timber
-import java.util.*
 
 /**
  * Util class for managing themes.
@@ -131,24 +130,16 @@ object ThemeUtils {
      */
     @ColorInt
     fun getColor(c: Context, @AttrRes colorAttribute: Int): Int {
-        if (mColorByAttr.containsKey(colorAttribute)) {
-            return mColorByAttr[colorAttribute] as Int
+        return mColorByAttr.getOrPut(colorAttribute) {
+            try {
+                val color = TypedValue()
+                c.theme.resolveAttribute(colorAttribute, color, true)
+                color.data
+            } catch (e: Exception) {
+                Timber.e(e, "Unable to get color")
+                ContextCompat.getColor(c, android.R.color.holo_red_dark)
+            }
         }
-
-        var matchedColor: Int
-
-        try {
-            val color = TypedValue()
-            c.theme.resolveAttribute(colorAttribute, color, true)
-            matchedColor = color.data
-        } catch (e: Exception) {
-            Timber.e(e, "Unable to get color")
-            matchedColor = ContextCompat.getColor(c, android.R.color.holo_red_dark)
-        }
-
-        mColorByAttr[colorAttribute] = matchedColor
-
-        return matchedColor
     }
 
     fun getAttribute(c: Context, @AttrRes attribute: Int): TypedValue? {