class MainActivity : AppCompatActivity() {

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

        hideKeyboard(this)
    }

    private fun hideKeyboard(activity: Activity) {
        val imm = activity.getSystemService(Activity.INPUT_METHOD_SERVICE) as InputMethodManager
        var view = activity.currentFocus
        if (view == null) {
            view = View(activity)
        }
        imm.hideSoftInputFromWindow(view.windowToken, 0)
    }

}