可以通过添加Activity的lifecycle方法及ExoPlayer的EventListener来解决这个问题。在onPause方法中暂停播放并取消EventListener注册，在onResume方法中恢复播放并重新注册EventListener。

以下是示例代码：

class MainActivity : AppCompatActivity() {

    private lateinit var player: SimpleExoPlayer

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        player = SimpleExoPlayer.Builder(this).build()
        val mediaItem = MediaItem.fromUri(Uri.parse("https://example.com/my_video.mp4"))
        player.setMediaItem(mediaItem)
        player.prepare()
        player.play()

        // Register player event listener
        player.addListener(playerEventListener)
    }
    
    override fun onPause() {
        super.onPause()
        player.pause()
        player.removeListener(playerEventListener)
    }

    override fun onResume() {
        super.onResume()
        player.play()
        player.addListener(playerEventListener)
    }

    override fun onDestroy() {
        super.onDestroy()
        player.release()
    }

    private val playerEventListener = object : Player.EventListener {
        override fun onPlaybackStateChanged(state: Int) {
            if (state == Player.STATE_IDLE || state == Player.STATE_ENDED) {
                // Unregister listener if idle or ended to prevent memory leaks
                player.removeListener(this)
            }
        }
    }
}