I want to add AdMob in my application but the AdView class is not found in my application

**build.gradle**

```
...
dependencies {
   api ('com.google.android.gms:play-services-ads:16.0.0'){force = true}
   api fileTree(dir: 'libs', include: ['*.jar'])
}

```

**layout.xml**

```
...

    <com.google.android.gms.ads.AdView
        android:id="@+id/banner_ad"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_alignParentBottom="true"
        app:adSize="FULL_BANNER"
        app:adUnitId="ca-app-pub-xxx/xxx"/>

...

```

**Log**

```
03-16 11:32:47.006 E/AndroidRuntime(2784): Caused by: java.lang.ClassNotFoundException: Didn't find class "com.google.android.gms.ads.AdView" on path: DexPathList[[zip file ...

```