Androidでキーボードを閉じる方法メモ ref: https://qiita.com/bassaer/items/0e412d9f36b2113ee8d0

file0.txt

class ContentFragment : Fragment() {

    private fun hideKeyboard() {
        val view = activity.currentFocus
        if (view != null) {
            val manager = activity.getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager
            manager.hideSoftInputFromWindow(view.windowToken, 0)
        }
    }

}