How to use CountDownTimer

CountDownTimerDemo.kt

package com.thomaskuenneth.playground

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.os.CountDownTimer
import android.util.Log

class CountDownTimerDemo : AppCompatActivity() {

    private val tag = CountDownTimerDemo::class.simpleName

    private val cdt = object : CountDownTimer(7000, 1000) {

        override fun onTick(millisUntilFinished: Long) {
            Log.d(tag, "seconds remaining: " + millisUntilFinished / 1000)
        }

        override fun onFinish() {
            Log.d(tag, "done")
        }
    }

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