diff --git a/app/src/androidTest/java/ch/sdp/vibester/GenreTemporaryTest.kt b/app/src/androidTest/java/ch/sdp/vibester/GenreTemporaryTest.kt
index da50ebd09..b2d7bf879 100644
--- a/app/src/androidTest/java/ch/sdp/vibester/GenreTemporaryTest.kt
+++ b/app/src/androidTest/java/ch/sdp/vibester/GenreTemporaryTest.kt
@@ -34,7 +34,7 @@ class GenreTemporaryTest {
     }
 
     @Test
-    fun GenreLayoutIsDisplayed() {
+    fun genreLayoutIsDisplayed() {
         onView(withId(R.id.rockButton)).check(matches(isDisplayed()))
         onView(withId(R.id.kpopButton)).check(matches(isDisplayed()))
         onView(withId(R.id.topTracksButton)).check(matches(isDisplayed()))
diff --git a/app/src/main/java/ch/sdp/vibester/activity/LyricsBelongGameActivity.kt b/app/src/main/java/ch/sdp/vibester/activity/LyricsBelongGameActivity.kt
index 4a42f68b8..32689f53d 100644
--- a/app/src/main/java/ch/sdp/vibester/activity/LyricsBelongGameActivity.kt
+++ b/app/src/main/java/ch/sdp/vibester/activity/LyricsBelongGameActivity.kt
@@ -53,11 +53,17 @@ class LyricsBelongGameActivity : AppCompatActivity() {
         }
     }
 
+    /**
+     * display the given String in lyricResult
+     */
     private fun updateSpeechResult(speechInput: String) {
         findViewById<TextView>(R.id.lyricResult).text = speechInput
         findViewById<Button>(R.id.lyricMatchButton).visibility = View.VISIBLE
     }
 
+    /**
+     * check if the given string belongs to the lyrics of the song
+     */
     private fun checkLyrics(lyricToBeCheck: String) {
         val service = LyricsOVHApiInterface.create()
         val call = service.getLyrics("Imagine Dragons", "Thunder")
diff --git a/app/src/main/java/ch/sdp/vibester/activity/MainActivity.kt b/app/src/main/java/ch/sdp/vibester/activity/MainActivity.kt
index 3e4810abf..8fad9f4ec 100644
--- a/app/src/main/java/ch/sdp/vibester/activity/MainActivity.kt
+++ b/app/src/main/java/ch/sdp/vibester/activity/MainActivity.kt
@@ -28,7 +28,6 @@ class MainActivity : AppCompatActivity() {
         val genreIntent = Intent(this, GenreTemporary::class.java)
         btnGenre.setOnClickListener {
             startActivity(genreIntent)
-
         }
 
     }
diff --git a/app/src/main/java/ch/sdp/vibester/activity/TypingGameActivity.kt b/app/src/main/java/ch/sdp/vibester/activity/TypingGameActivity.kt
index fd75ad875..266f1891d 100644
--- a/app/src/main/java/ch/sdp/vibester/activity/TypingGameActivity.kt
+++ b/app/src/main/java/ch/sdp/vibester/activity/TypingGameActivity.kt
@@ -38,27 +38,27 @@ class TypingGameActivity : AppCompatActivity() {
         /**
          * Print Toast message to announce the user if he wons or not
          */
-        private fun hasWon(ctx: Context, hasWon: Boolean, itwas: Song){
+        private fun hasWon(ctx: Context, hasWon: Boolean, itWas: Song){
             if(hasWon){
                 Toast.makeText(ctx,"Well Done!",Toast.LENGTH_SHORT).show()
             }else{
-                Toast.makeText(ctx,"Sadly you're wrong, it was: "+itwas.getTrackName()+" by "+itwas.getArtistName(),Toast.LENGTH_SHORT).show()
+                Toast.makeText(ctx,"Sadly you're wrong, it was: "+itWas.getTrackName()+" by "+itWas.getArtistName(),Toast.LENGTH_SHORT).show()
             }
         }
 
         /**
          * Generate a change of intent at the end of the game
          */
-        fun intentGen(ctx: Context, choosenSong: Song?, playedSong: Song):Intent{
+        fun intentGen(ctx: Context, chosenSong: Song?, playedSong: Song):Intent{
             val newIntent = Intent(ctx, TypingGameActivity::class.java)
             newIntent.putExtra("song", playedSong)
             newIntent.putExtra("isPlaying", false)
-            if(choosenSong != null && choosenSong.getTrackName() == playedSong.getTrackName() && choosenSong.getArtistName() == playedSong.getArtistName()){
+            if(chosenSong != null && chosenSong.getTrackName() == playedSong.getTrackName() && chosenSong.getArtistName() == playedSong.getArtistName()){
                 newIntent.putExtra("hasWon", true)
             }else{
                 newIntent.putExtra("hasWon", false)
             }
-            newIntent.setFlags(FLAG_ACTIVITY_NEW_TASK)
+            newIntent.flags = FLAG_ACTIVITY_NEW_TASK
             return newIntent
         }
 
@@ -82,7 +82,7 @@ class TypingGameActivity : AppCompatActivity() {
             frameLay.addView(linLay)
             guessLayout.addView(frameLay)
 
-            //Create the Listener that is executed if we click on the framelayer
+            //Create the Listener that is executed if we click on the frameLayer
             frameLay.setOnClickListener {
                 frameLay.setBackgroundColor(getColor(ctx, R.color.tiffany_blue))
                 guessLayout.removeAllViews()
@@ -124,7 +124,7 @@ class TypingGameActivity : AppCompatActivity() {
          */
         fun generateText(txt: String, ctx: Context): TextView {
             val txtView = TextView(ctx)
-            txtView.setText(txt)
+            txtView.text = txt
             txtView.gravity = Gravity.CENTER
             txtView.minHeight= 200
             txtView.textSize = 20F
@@ -178,7 +178,7 @@ class TypingGameActivity : AppCompatActivity() {
             if(!isPlaying){
                 //Is the activity showing the result
                 hasWon(this, hasWon, playableSong)
-                inputTxt.setKeyListener(null)
+                inputTxt.keyListener = null
             }else{
                 //Is the activity playing music
                 mediaPlayer = AudioPlayer.playAudio(playableSong.getPreviewUrl())
diff --git a/app/src/main/java/ch/sdp/vibester/api/ItunesMusicApi.kt b/app/src/main/java/ch/sdp/vibester/api/ItunesMusicApi.kt
index d6e04b1aa..8f6f4052a 100644
--- a/app/src/main/java/ch/sdp/vibester/api/ItunesMusicApi.kt
+++ b/app/src/main/java/ch/sdp/vibester/api/ItunesMusicApi.kt
@@ -9,7 +9,7 @@ import java.util.concurrent.CompletableFuture
 class ItunesMusicApi private constructor(){
 
     companion object{
-        private val LOOKUP_URL_BASE = "https://itunes.apple.com/search?media=music&"
+        private const val LOOKUP_URL_BASE = "https://itunes.apple.com/search?media=music&"
 
         /**
          * Given a String query it will provide the music url preview
@@ -19,10 +19,10 @@ class ItunesMusicApi private constructor(){
          * @return CompletableFuture<String> that contains the result of the query
          */
         fun querySong(query: String, okHttp: OkHttpClient, limit: Int, baseUrl: String = LOOKUP_URL_BASE): CompletableFuture<String> {
-            val buildedUrl = baseUrl+"limit="+limit+"&term="+query.replace(' ', '+')
-            val req = okhttp3.Request.Builder().url(buildedUrl).build()
+            val builtUrl = baseUrl+"limit="+limit+"&term="+query.replace(' ', '+')
+            val req = okhttp3.Request.Builder().url(builtUrl).build()
 
-            var retFuture = CompletableFuture<String>()
+            val retFuture = CompletableFuture<String>()
 
             okHttp.newCall(req).enqueue(ApiCallback(retFuture))
 
diff --git a/app/src/main/java/ch/sdp/vibester/api/LastfmApi.kt b/app/src/main/java/ch/sdp/vibester/api/LastfmApi.kt
index e339a0262..19f9701b2 100644
--- a/app/src/main/java/ch/sdp/vibester/api/LastfmApi.kt
+++ b/app/src/main/java/ch/sdp/vibester/api/LastfmApi.kt
@@ -12,8 +12,8 @@ import java.util.concurrent.CompletableFuture
 class LastfmApi private constructor(){
 
         companion object{
-            private val API_KEY = "52bfdc690dd8373bba5351571a01ac14"
-            private val LOOKUP_URL_BASE ="https://ws.audioscrobbler.com/2.0/"
+            private const val API_KEY = "52bfdc690dd8373bba5351571a01ac14"
+            private const val LOOKUP_URL_BASE ="https://ws.audioscrobbler.com/2.0/"
 
             /**
              * Provide a list of songs by given tag or chart
@@ -22,7 +22,7 @@ class LastfmApi private constructor(){
              * @param baseUrl: baseUrl if changed
              */
             fun querySongList(okHttp: OkHttpClient, params:LastfmUri, baseUrl: String = LOOKUP_URL_BASE): CompletableFuture<String> {
-                var builtUri: Uri= Uri.parse(baseUrl)
+                val builtUri: Uri= Uri.parse(baseUrl)
                     .buildUpon()
                     .appendQueryParameter("method", params.method)
                     .appendQueryParameter("api_key", API_KEY)
@@ -34,7 +34,7 @@ class LastfmApi private constructor(){
                 val uri = builtUri.toString()
                 val req = Request.Builder().url(uri).build()
 
-                var retFuture = CompletableFuture<String>()
+                val retFuture = CompletableFuture<String>()
 
                 okHttp.newCall(req).enqueue(ApiCallback(retFuture))
 
diff --git a/app/src/main/java/ch/sdp/vibester/api/LastfmHelper.kt b/app/src/main/java/ch/sdp/vibester/api/LastfmHelper.kt
index 2ffc6563f..119927bc8 100644
--- a/app/src/main/java/ch/sdp/vibester/api/LastfmHelper.kt
+++ b/app/src/main/java/ch/sdp/vibester/api/LastfmHelper.kt
@@ -16,7 +16,7 @@ class LastfmHelper {
 
     companion object{
         private var pageLimitQueryTwo = 200;
-        private val GAME_SIZE = 10;
+        private const val GAME_SIZE = 10;
 
         /**
          * Function that performs queries to two pages within given tag
@@ -24,24 +24,31 @@ class LastfmHelper {
          * @param tag: tag to retrieve songs. If method BY_CHART is used, tag is empty.
          * @return list of songs in a format ("$songName $artistName")
          */
-        fun getRandomSongList(method: String, tag:String = ""): List<String> {
-            val firstQuery = SongList(LastfmApi.querySongList(OkHttpClient(),
-                LastfmUri(method = method, tag = tag)).get())
+        fun getRandomSongList(method: String, tag: String = ""): List<String> {
+            val firstQuery = SongList(
+                LastfmApi.querySongList(
+                    OkHttpClient(),
+                    LastfmUri(method = method, tag = tag)
+                ).get()
+            )
             val firstSongList = firstQuery.getSongList()
             val pagesQueryOne = firstQuery.getTotalPages().toInt()
 
-            if(pagesQueryOne < pageLimitQueryTwo){
+            if (pagesQueryOne < pageLimitQueryTwo) {
                 pageLimitQueryTwo = pagesQueryOne
             }
 
-            val pageQueryTwo =(2..pageLimitQueryTwo).random()
-            val secondQuery = SongList(LastfmApi.querySongList(OkHttpClient(),
-                LastfmUri(method = method, tag = tag, page = pageQueryTwo.toString())).get())
+            val pageQueryTwo = (2..pageLimitQueryTwo).random()
+            val secondQuery = SongList(
+                LastfmApi.querySongList(
+                    OkHttpClient(),
+                    LastfmUri(method = method, tag = tag, page = pageQueryTwo.toString())
+                ).get()
+            )
             val secondSongList = secondQuery.getSongList()
 
             val mergedLists = merge(firstSongList, secondSongList)
-            var finalList = mergedLists.asSequence().shuffled().take(GAME_SIZE).toList()
-            return finalList
+            return mergedLists.asSequence().shuffled().take(GAME_SIZE).toList()
         }
 
         fun <T> merge(first: List<T>, second: List<T>): List<T> {
diff --git a/app/src/main/java/ch/sdp/vibester/auth/FireBaseAuthenticator.kt b/app/src/main/java/ch/sdp/vibester/auth/FireBaseAuthenticator.kt
index c9a0fcce9..dc256f7cc 100644
--- a/app/src/main/java/ch/sdp/vibester/auth/FireBaseAuthenticator.kt
+++ b/app/src/main/java/ch/sdp/vibester/auth/FireBaseAuthenticator.kt
@@ -11,7 +11,6 @@ import com.google.firebase.ktx.Firebase
 
 class FireBaseAuthenticator() {
 
-
     val auth: FirebaseAuth = Firebase.auth
 
 
diff --git a/app/src/main/java/ch/sdp/vibester/model/Song.kt b/app/src/main/java/ch/sdp/vibester/model/Song.kt
index fb41c77bf..d0ce89877 100644
--- a/app/src/main/java/ch/sdp/vibester/model/Song.kt
+++ b/app/src/main/java/ch/sdp/vibester/model/Song.kt
@@ -76,7 +76,7 @@ class Song(jsonO: JSONObject): Serializable{
                 val jsonObj = JSONObject(str)
                 val countResult = jsonObj.getInt("resultCount")
                 val jsonArray = jsonObj.getJSONArray("results")
-                for (i in 0..(countResult-1)){
+                for (i in 0 until countResult){
                     myList.add(Song(jsonArray.getJSONObject(i)))
                 }
                 return myList
diff --git a/app/src/main/java/ch/sdp/vibester/model/SongList.kt b/app/src/main/java/ch/sdp/vibester/model/SongList.kt
index fd2183726..80036523a 100644
--- a/app/src/main/java/ch/sdp/vibester/model/SongList.kt
+++ b/app/src/main/java/ch/sdp/vibester/model/SongList.kt
@@ -19,11 +19,11 @@ class SongList(jsonMeta: String) {
     init {
         try {
             val jsonObj = JSONObject(jsonMeta)
-            var jsonRes = jsonObj.getJSONObject("tracks")
-            var nonFilteredSongs = jsonRes.getJSONArray("track")
+            val jsonRes = jsonObj.getJSONObject("tracks")
+            val nonFilteredSongs = jsonRes.getJSONArray("track")
             filterSongs(nonFilteredSongs)
 
-            var attributes = jsonRes.getJSONObject("@attr")
+            val attributes = jsonRes.getJSONObject("@attr")
             page = attributes.getString("page")
             songsPerPage = attributes.getString("perPage")
             totalPages = attributes.getString("totalPages")
@@ -43,7 +43,7 @@ class SongList(jsonMeta: String) {
         val songsLength = nonFilteredSongs.length()
         var  i = 0
         while(i < songsLength) {
-            var songObj = nonFilteredSongs.getJSONObject(i)
+            val songObj = nonFilteredSongs.getJSONObject(i)
             val songName = songObj.getString("name")
             val artistDetails = songObj.getJSONObject("artist")
             val artistName = artistDetails.getString("name")