How to add AdMob to Android app

buildscript { repositories { google() jcenter() } dependencies { classpath 'com.google.gms:google-services:4.3.2' } } 

class Version { class Firebase { static def analytics = "17.2.0" static def ads = "18.2.0" } } dependencies { implementation "com.google.firebase:firebase-analytics:$Version.Firebase.analytics" implementation "com.google.firebase:firebase-ads:$Version.Firebase.ads" } apply plugin: 'com.google.gms.google-services' 

<manifest> <application> <!-- Sample AdMob App ID: ca-app-pub-3940256099942544~3347511713 --> <meta-data android:name="com.google.android.gms.ads.APPLICATION_ID" android:value="[ADMOB_APP_ID]"/> </application> </manifest> 

class MyApplication: Application() { override fun onCreate() { super.onCreate() MobileAds.initialize(this) } } 

<com.google.android.gms.ads.AdView xmlns:ads="http://schemas.android.com/apk/res-auto" android:id="@+id/adView" android:layout_width="match_parent" android:layout_height="wrap_content" ads:adSize="BANNER" ads:adUnitId="ca-app-pub-123456/123456" ads:layout_constraintBottom_toBottomOf="parent" ads:layout_constraintLeft_toLeftOf="parent" ads:layout_constraintRight_toRightOf="parent"/> 

import com.google.android.gms.ads.AdRequest import com.google.android.gms.ads.AdView val request = AdRequest.Builder().build() adView.loadAd(request) 

dependencies { implementation 'com.google.android.gms:play-services-ads:18.2.0' } 

 android { defaultConfig { multiDexEnabled true } } dependencies { implementation 'com.android.support:multidex:1.0.3' }