How do you add a song to the end of an ExoPlayer playlist when it reaches STATE_ENDED and start playback from that added song?

Question

I am trying to wait for ExoPlayer to finish playing a playlist and then append a song to the end of the playlist and starting the playlist from that added song.

I tried doing this, but it does not work:

        override fun onPlaybackStateChanged(playbackState: Int) {
            super.onPlaybackStateChanged(playbackState)
            if (playbackState == STATE_ENDED) {
                playerHolder.getPlayer().addMediaItem(
                    playerHolder.getPlayer().currentMediaItem!!
                )
                playerHolder.getPlayer().play()
            }
        }

Nothing is played after that code is run.

Answer 1

The reason the code in the question does not work is because the playWhenReady field of the player is true when in the callback, so play() has no effect. A seek call is needed to start the playback. The following code does what was trying to be done.

        override fun onPlaybackStateChanged(playbackState: Int) {
            super.onPlaybackStateChanged(playbackState)
            if (playbackState == STATE_ENDED) {
                val player = playerHolder.getPlayer()
                player.addMediaItem(
                    player.currentMediaItem!!

                )
                player.seekTo(
                    player.mediaItemCount - 1,
                    C.TIME_UNSET
                )
            }
        }