[android] How to show Snackbar when Activity starts?

A utils function for show snack bar

fun showSnackBar(activity: Activity, message: String, action: String? = null,
    actionListener: View.OnClickListener? = null, duration: Int = Snackbar.LENGTH_SHORT) {
    val snackBar = Snackbar.make(activity.findViewById(android.R.id.content), message, duration)
        .setBackgroundColor(Color.parseColor("#CC000000")) // todo update your color
        .setTextColor(Color.WHITE)
    if (action != null && actionListener!=null) {
        snackBar.setAction(action, actionListener)
    }
    snackBar.show()
}

Example using in Activity

  showSnackBar(this, "No internet")
  showSnackBar(this, "No internet", duration = Snackbar.LENGTH_LONG)
  showSnackBar(activity, "No internet", "OK", View.OnClickListener { 
       // handle click 
  })

Example using in Fragment

  showSnackBar(getActivity(), "No internet")

Hope it help