Android: Test Ads not displaying
<p>i am trying to add Ads to my current activity but the activity is not showing any <strong>Ad</strong> . i have also add internet permission to <strong>Android Manifest.xml</strong>  </p>

<p>Here is my  </p>

<p><strong>.Gradle File</strong></p>

<pre><code> apply plugin: 'com.android.application'

    android {
        compileSdkVersion 23
        buildToolsVersion "23.0.0"

        defaultConfig {
            applicationId "sms.and.call.alert.flashlight.lpa.com.myapplication"
            minSdkVersion 15
            targetSdkVersion 23
            versionCode 1
            versionName "1.0"
        }
        buildTypes {
            release {
                minifyEnabled false
                proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
            }
        }
    }

    dependencies {
        compile fileTree(dir: 'libs', include: ['*.jar'])
        testCompile 'junit:junit:4.12'
        compile 'com.google.android.gms:play-services:9.6.0'

        compile 'com.google.firebase:firebase-ads:9.6.0'
    }
</code></pre>

<p>This is <strong>MainActivity</strong></p>

<pre><code>  public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        MobileAds.initialize(getApplicationContext(), "ca-app-pub-3940256099942544~3347511713");
        AdView mAdView = (AdView) findViewById(R.id.adView);
        AdRequest request = new AdRequest.Builder()
                .addTestDevice(AdRequest.DEVICE_ID_EMULATOR)        // All emulators
                  // An example device ID
                .build();
        mAdView.loadAd(request);

    }
}
</code></pre>

<p>This is <strong>MainActivity.xml</strong></p>

<pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
&lt;RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:ads="http://schemas.android.com/apk/res-auto"

    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="sms.and.call.alert.flashlight.lpa.com.myapplication.MainActivity"&gt;
    &lt;com.google.android.gms.ads.AdView
        android:id="@+id/adView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_alignParentBottom="true"
        ads:adSize="BANNER"
        ads:adUnitId="@string/banner_ad_unit_id"&gt;
    &lt;/com.google.android.gms.ads.AdView&gt;
    &lt;TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!" /&gt;
&lt;/RelativeLayout&gt;
</code></pre>