convert to Kotlin

app/build.gradle

@@ -1,4 +1,5 @@
 apply plugin: 'com.android.application'
+apply plugin: 'kotlin-android'
 
 android {
     compileSdkVersion 25
@@ -36,6 +37,8 @@ dependencies {
     androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
         exclude group: 'com.android.support', module: 'support-annotations'
     })
-    compile 'com.android.support:appcompat-v7:25.1.1'
+    compile "com.android.support:appcompat-v7:$support_version"
+    compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
+    compile "org.jetbrains.anko:anko-common:$anko_version"
     testCompile 'junit:junit:4.12'
 }

app/src/main/java/com/henrysnoek/spotifyandroidsdkexample/MainActivity.kt

@@ -0,0 +1,102 @@
+package com.henrysnoek.spotifyandroidsdkexample
+
+import android.app.Activity
+import android.content.Intent
+import android.os.Bundle
+import android.util.Log
+
+import com.spotify.sdk.android.authentication.AuthenticationClient
+import com.spotify.sdk.android.authentication.AuthenticationRequest
+import com.spotify.sdk.android.authentication.AuthenticationResponse
+import com.spotify.sdk.android.player.Config
+import com.spotify.sdk.android.player.ConnectionStateCallback
+import com.spotify.sdk.android.player.Error
+import com.spotify.sdk.android.player.Player
+import com.spotify.sdk.android.player.PlayerEvent
+import com.spotify.sdk.android.player.Spotify
+import com.spotify.sdk.android.player.SpotifyPlayer
+
+class MainActivity : Activity(), Player.NotificationCallback, ConnectionStateCallback {
+
+    private var mPlayer: Player? = null
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.activity_main)
+
+        val builder = AuthenticationRequest.Builder(CLIENT_ID,
+                AuthenticationResponse.Type.TOKEN,
+                REDIRECT_URI)
+        builder.setScopes(arrayOf("user-read-private", "streaming"))
+        val request = builder.build()
+
+        AuthenticationClient.openLoginActivity(this, REQUEST_CODE, request)
+    }
+
+    override fun onActivityResult(requestCode: Int, resultCode: Int, intent: Intent) {
+        super.onActivityResult(requestCode, resultCode, intent)
+
+        // Check if result comes from the correct activity
+        if (requestCode == REQUEST_CODE) {
+            val response = AuthenticationClient.getResponse(resultCode, intent)
+            if (response.type == AuthenticationResponse.Type.TOKEN) {
+                val playerConfig = Config(this, response.accessToken, CLIENT_ID)
+                Spotify.getPlayer(playerConfig, this, object : SpotifyPlayer.InitializationObserver {
+                    override fun onInitialized(spotifyPlayer: SpotifyPlayer) {
+                        mPlayer = spotifyPlayer
+                        mPlayer!!.addConnectionStateCallback(this@MainActivity)
+                        mPlayer!!.addNotificationCallback(this@MainActivity)
+                    }
+
+                    override fun onError(throwable: Throwable) {
+                        Log.e("MainActivity", "Could not initialize player: " + throwable.message)
+                    }
+                })
+            }
+        }
+    }
+
+    override fun onDestroy() {
+        Spotify.destroyPlayer(this)
+        super.onDestroy()
+    }
+
+    override fun onPlaybackEvent(playerEvent: PlayerEvent) {
+        Log.d("MainActivity", "Playback event received: " + playerEvent.name)
+    }
+
+    override fun onPlaybackError(error: Error) {
+        Log.d("MainActivity", "Playback error received: " + error.name)
+    }
+
+    override fun onLoggedIn() {
+        Log.d("MainActivity", "User logged in")
+
+        mPlayer!!.playUri(null, "spotify:track:6JEK0CvvjDjjMUBFoXShNZ", 0, 0)
+    }
+
+    override fun onLoggedOut() {
+        Log.d("MainActivity", "User logged out")
+    }
+
+    override fun onLoginFailed(error: Error) {
+        Log.d("MainActivity", "Login failed")
+    }
+
+    override fun onTemporaryError() {
+        Log.d("MainActivity", "Temporary error occurred")
+    }
+
+    override fun onConnectionMessage(message: String) {
+        Log.d("MainActivity", "Received connection message: " + message)
+    }
+
+    companion object {
+        private val CLIENT_ID = BuildConfig.CLIENT_ID
+        private val REDIRECT_URI = BuildConfig.REDIRECT_URI
+
+        // Request code that will be used to verify if the result comes from correct activity
+        // Can be any integer
+        private val REQUEST_CODE = 1337
+    }
+}

build.gradle

@@ -1,11 +1,15 @@
 // Top-level build file where you can add configuration options common to all sub-projects/modules.
 
 buildscript {
+    ext.support_version = '25.2.0'
+    ext.kotlin_version = '1.0.6'
+    ext.anko_version = '0.9.1'
     repositories {
         jcenter()
     }
     dependencies {
         classpath 'com.android.tools.build:gradle:2.2.3'
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
 
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files