如何在广告关闭时启动第二个活动？(Kotlin)

import android.content.Intent
import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity
import com.google.android.gms.ads.AdListener
import com.google.android.gms.ads.AdRequest
import com.google.android.gms.ads.AdView

class MainActivity : AppCompatActivity() {
    private lateinit var adView: AdView

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

        adView = findViewById(R.id.adView)
        val adRequest = AdRequest.Builder().build()
        adView.loadAd(adRequest)

        adView.adListener = object : AdListener() {
            override fun onAdClosed() {
                super.onAdClosed()
                // 广告关闭时启动第二个活动
                val intent = Intent(this@MainActivity, SecondActivity::class.java)
                startActivity(intent)
            }
        }
    }
}