Add an Admob adaptive ad banner in just a few lines of code (Kotlin)

AdmobAdaptiveBannerAdController.kt

package com.example.yourapp

import android.app.Activity
import com.google.android.gms.ads.AdRequest
import com.google.android.gms.ads.AdSize
import com.google.android.gms.ads.AdView
import com.google.android.gms.ads.MobileAds
import android.util.DisplayMetrics
import android.widget.FrameLayout

/**
 *
 * @author Jaimies
 *
 * @description In your activity or fragment, add a companion object that extends AdmobAdaptiveBannerAdController and call the initializeAdBanner() method
 *
 * @param activity : Activity to use for working with ads
 * @param adContainerViewId : Id of an element that will contain the add banner (mostly FrameLayout)
 * @param adKeyId : Resource id of a string that contains the Admob banner key
 *
* */

open class AdmobAdaptiveBannerAdController {

    private lateinit var mAdView: AdView

    fun initializeAdBanner(activity: Activity, adContainerViewId : Int, adKeyId : Int) {

        // Initialize the Mobile Ads SDK.
        MobileAds.initialize(activity) { }

        val adContainerView = activity.findViewById<FrameLayout>(adContainerViewId)

        // Step 1 - Create an AdView and set the ad unit ID on it.
        mAdView = AdView(activity)
        mAdView.adUnitId = activity.getString(adKeyId)
        
        // Add adView to its container and load ads
        adContainerView.addView(mAdView)
        loadBanner(activity)

    }

    private fun loadBanner(activity: Activity) {

        // Create an ad request. Check your logcat output for the hashed device ID
        // to get test ads on a physical device, e.g.,
        // "Use AdRequest.Builder.addTestDevice("ABCDE0123") to get test ads on this
        // device."
        val adRequest = AdRequest.Builder().addTestDevice(AdRequest.DEVICE_ID_EMULATOR)
            .build()
        
        val adSize = getAdSize(activity)

        // Step 4 - Set the adaptive ad size on the ad view.
        mAdView.adSize = adSize

        // Step 5 - Start loading the ad in the background.
        mAdView.loadAd(adRequest)

    }

    private fun getAdSize(activity: Activity) : AdSize {

        // Step 2 - Determine the screen width (less decorations) to use for the ad width.
        val display = activity.windowManager.defaultDisplay
        val outMetrics = DisplayMetrics()
        display.getMetrics(outMetrics)

        val widthPixels = outMetrics.widthPixels.toFloat()
        val density = outMetrics.density

        val adWidth = (widthPixels / density).toInt()

        // Step 3 - Get adaptive ad size and return for setting on the ad view.
        return AdSize.getCurrentOrientationBannerAdSizeWithWidth(activity, adWidth)

    }

}