Seekbar不使用背景音乐

Question

我在我的应用程序的原始文件夹中添加了背景音乐＆＃34; bg_music＆＃34;并使用seekbar创建一个活动，但我使用的seekbar无法使用我的背景音乐，因为它不随音乐增加或减少。

这是我的代码：

class MusicActivity : Activity() {

    private var imageButton6: ImageButton? = null

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

        //Back button event
        imageButton6 = findViewById(R.id.imageButton6) as ImageButton
        imageButton6!!.setOnClickListener {
            val i = Intent(applicationContext,
                    HomeActivity::class.java)
            startActivity(i)
            finish()
        }

        // call method VolumeControls()
        VolumeControls()

    }

    private fun VolumeControls() {
        try {
            val txtView = findViewById(R.id.textView) as TextView // TextView
            val seekBar2 = findViewById(R.id.seekBar) as SeekBar // SeekBar
            val audioManager = getSystemService(Context.AUDIO_SERVICE) as AudioManager
            seekBar2.max = audioManager.getStreamMaxVolume(AudioManager.STREAM_MUSIC)
            seekBar2.progress = audioManager.getStreamVolume(AudioManager.STREAM_MUSIC)

            // TextView
            txtView.text = audioManager
                    .getStreamVolume(AudioManager.STREAM_MUSIC).toString()


            seekBar2.setOnSeekBarChangeListener(object : OnSeekBarChangeListener {
                override fun onStopTrackingTouch(arg0: SeekBar) {}

                override fun onStartTrackingTouch(arg0: SeekBar) {}

                override fun onProgressChanged(arg0: SeekBar, progress: Int, arg2: Boolean) {
                    audioManager.setStreamVolume(AudioManager.STREAM_MUSIC, progress, 0)
                    txtView.text = progress.toString()
                }
            })
        } catch (e: Exception) {

            e.printStackTrace()
        }

    }