用户退出应用后显示的插页式广告

Question

嗨，所以这是我的插页式广告代码，我希望将此代码转换为用户关闭我的应用时，它会立即关闭广告

//我// prepareAd（）

val scheduler = Executors.newSingleThreadScheduledExecutor()
scheduler.scheduleAtFixedRate({
    runOnUiThread {
        if (mInterstitialAd!!.isLoaded) {
            mInterstitialAd!!.show()
        } else {
            Log.d("Tag", "Interstitial not loaded")
        }
        prepareAd()
    }
}, 5, 20, TimeUnit.SECONDS)

fun onDestroy() {
    Log.d("MainActivty", "onDestroy removing callbacks...")
    scheduler.removeCallbacks(scheduler)
    mInterstitialAd = null
    super.onDestroy()
}
//I//