Exoplayer builder gives error when back pressed and open video again

Question

I am using ExoPlayer to play videos. Everything is normal and working until back pressing.I am using recycler view. User is pressing an item to enter video.But when user back pressed and open another video or same video again, player builder gives the error below. I have never seen a solution about this on the net. And also I need to say that I am using the same builder method on the document.

this is the error:

Process: com.example.exoplayer, PID: 19208
   java.lang.NoClassDefFoundError: Failed resolution of: Lcom/google/android/exoplayer2/source/ads/AdsMediaSource$MediaSourceFactory;
       at java.lang.Class.classForName(Native Method)
       at java.lang.Class.forName(Class.java:453)
       at java.lang.Class.forName(Class.java:378)
       at com.google.android.exoplayer2.source.DefaultMediaSourceFactory.loadDelegates(DefaultMediaSourceFactory.java:321)
       at com.google.android.exoplayer2.source.DefaultMediaSourceFactory.<init>(DefaultMediaSourceFactory.java:152)
       at com.google.android.exoplayer2.source.DefaultMediaSourceFactory.<init>(DefaultMediaSourceFactory.java:127)
       at com.google.android.exoplayer2.SimpleExoPlayer$Builder.<init>(SimpleExoPlayer.java:195)
       at com.google.android.exoplayer2.SimpleExoPlayer$Builder.<init>(SimpleExoPlayer.java:153)
       at com.example.exoplayer.MainActivity.initializePlayer(MainActivity.kt:193)
       at com.example.exoplayer.MainActivity.onStart(MainActivity.kt:70)
       at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1333)
       at android.app.Activity.performStart(Activity.java:6992)
       at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2780)
       at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892)
       at android.app.ActivityThread.-wrap11(Unknown Source:0)
       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1593)
       at android.os.Handler.dispatchMessage(Handler.java:105)
       at android.os.Looper.loop(Looper.java:164)
       at android.app.ActivityThread.main(ActivityThread.java:6541)
       at java.lang.reflect.Method.invoke(Native Method)
       at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
    Caused by: java.lang.ClassNotFoundException: Didn't find class "com.google.android.exoplayer2.source.ads.AdsMediaSource$MediaSourceFactory" on path: DexPathList[[zip file "/data/app/com.example.exoplayer-V2UiSJoFtK6lpPhAy-YB-g==/base.apk"],nativeLibraryDirectories=[/data/app/com.example.exoplayer-V2UiSJoFtK6lpPhAy-YB-g==/lib/x86, /system/lib, /vendor/lib]]
       at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:93)
       at java.lang.ClassLoader.loadClass(ClassLoader.java:379)

This is my initialize and release methods:

initialize()

   private fun initializePlayerXml(currentXmlLink: String) {
       if (player == null) {
           val trackSelector = DefaultTrackSelector(this)
           trackSelector.setParameters(
               trackSelector.buildUponParameters().setMaxVideoSizeSd()
           )
           player = SimpleExoPlayer.Builder(this)
               .setTrackSelector(trackSelector)
               .build()

       }
       if (player!!.bufferedPosition == 0L) {
           playButton.setImageResource(R.drawable.ic_pause)
       }

       playButton.setOnClickListener {
           if (player!!.isPlaying) {
               player!!.pause()
               playButton.setImageResource(R.drawable.ic_play)
           } else {
               player!!.play()
               playButton.setImageResource(R.drawable.ic_pause)
           }


       }
       val doubleClickForwardFun = DoubleClick(object : DoubleClickListener {
           override fun onSingleClickEvent(view: View?) {

           }

           override fun onDoubleClickEvent(view: View?) {
               val currentPosition = player!!.currentPosition
               player!!.seekTo(currentPosition + 10000)
           }
       })

       val doubleClickBackwardFun = DoubleClick(object : DoubleClickListener {
           override fun onSingleClickEvent(view: View?) {

           }

           override fun onDoubleClickEvent(view: View?) {
               val currentPosition = player!!.currentPosition
               player!!.seekTo(currentPosition - 10000)
           }
       })


       forwardButton.setOnClickListener {
           val currentPosition = player!!.currentPosition
           player!!.seekTo(currentPosition + 10000)
       }
       backwardButton.setOnClickListener {
           val currentPosition = player!!.currentPosition
           player!!.seekTo(currentPosition - 10000)

       }
       doubleClickBackward.setOnClickListener(doubleClickBackwardFun)
       doubleClickForward.setOnClickListener(doubleClickForwardFun)

       val mediaItem =
           MediaItem.Builder()
               .setUri(currentXmlLink)
               .setMimeType(MimeTypes.APPLICATION_MPD)
               .build()
       player!!.addMediaItem(mediaItem)
       player!!.addMediaItem(mediaItem)

       playerView!!.player = player
       player!!.playWhenReady = playWhenReady
       player!!.seekTo(currentWindow, playbackPosition)
       playbackStateListener.let { player!!.addListener(it) }
       player!!.prepare()
   }

release()

   private fun releasePlayer() {
       if (player != null) {
           player!!.removeListener(playbackStateListener)
           player!!.release()
           player!!.stop()
           player = null
       }
   }

Answer 1

I just found the solution.The problem occurs when different versions of exoplayer used. I am using these to solve the problem.

    implementation 'com.google.android.exoplayer:exoplayer:2.12.1'
    implementation 'com.google.android.exoplayer:exoplayer-core:2.12.1'
    implementation 'com.google.android.exoplayer:exoplayer-dash:2.12.1'
    implementation 'com.google.android.exoplayer:exoplayer-ui:2.12.1'
    implementation 'com.google.android.exoplayer:exoplayer-hls:2.12.1'

for more information check my issue on Github here.