Animate appbar

AppBarAnimation.kt

fun animationAppBarDown(appBar: AppBarLayout) {
            object : CountDownTimer(300, 1) {
                override fun onTick(millisUntilFinished: Long) {
                    appBar.translationY = (-appBar.height).toFloat()
                }

                override fun onFinish() {
                    appBar.animate()
                            .translationY(0f)
                            .setDuration(500).start()
                }
            }.start()
        }