Test Banner Ad doesn't show

Question

I'm trying to load a banner Ad just for practice. But the ad doesn't show up.

-xml code

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:ads="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <com.google.android.gms.ads.AdView
        android:id="@+id/adView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"

        android:layout_alignParentBottom="true"
        ads:adSize="BANNER"
        ads:adUnitId="ca-app-pub-3940256099942544/6300978111" />

</LinearLayout>

I filled the ads:adUnitId with the test banner unit Id from here

-MainActivity.java

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import com.google.android.gms.ads.AdRequest;
import com.google.android.gms.ads.AdView;
import com.google.android.gms.ads.MobileAds;
import com.google.android.gms.ads.RequestConfiguration;
import com.google.android.gms.ads.initialization.InitializationStatus;
import com.google.android.gms.ads.initialization.OnInitializationCompleteListener;
import java.util.Arrays;
import java.util.List;
import static com.google.android.gms.ads.MobileAds.initialize;

public class MainActivity extends AppCompatActivity {
    private AdView mAdView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        MobileAds.initialize(this, new OnInitializationCompleteListener() {
            @Override
            public void onInitializationComplete(@NonNull @org.jetbrains.annotations.NotNull InitializationStatus initializationStatus) {

            }
        });
        
        /*
        List<String> testDeviceIds = Arrays.asList("")
        RequestConfiguration configuration = new RequestConfiguration.Builder().setTestDeviceIds(testDeviceIds).build();
        MobileAds.setRequestConfiguration(configuration);*/
        
        mAdView = findViewById(R.id.adView);
        AdRequest adRequest = new AdRequest.Builder()
                .build();
        mAdView.loadAd(adRequest);
    }
}

The annotated part is one solution I found from google but I couldn't get the message like below so I couldn't fill it.

I/Ads: Use RequestConfiguration.Builder.setTestDeviceIds(Arrays.asList("33BE2250B43518CCDA7DE426D04EE231"))
to get test ads on this device."

-build.gradle(:app)

plugins {
    id 'com.android.application'
}

android {
    compileSdkVersion 31
    buildToolsVersion "30.0.3"

defaultConfig {
    applicationId "com.***"
    minSdkVersion 19
    targetSdkVersion 31
    versionCode 1
    versionName "1.0"
    multiDexEnabled true

    testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
}

buildTypes {
    release {
        minifyEnabled false
        proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
    }
}
compileOptions {
    sourceCompatibility JavaVersion.VERSION_1_8
    targetCompatibility JavaVersion.VERSION_1_8
}
}

dependencies {

implementation 'androidx.multidex:multidex:2.0.1'
implementation 'androidx.appcompat:appcompat:1.4.0'
implementation 'com.google.android.material:material:1.6.1'
implementation 'androidx.constraintlayout:constraintlayout:2.1.4'
implementation 'com.google.android.gms:play-services-ads:21.5.0'
implementation 'org.jetbrains:annotations:15.0'
testImplementation 'junit:junit:4.+'
androidTestImplementation 'androidx.test.ext:junit:1.1.3'
androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'
}

-build.gradle(:project)

buildscript {
    repositories {
        google()
        mavenCentral()
    }
    dependencies {
        classpath "com.android.tools.build:gradle:4.2.1"

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        google()
        mavenCentral()
        jcenter() // Warning: this repository is going to shut down soon
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

-Manifest

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="***">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.***">
        <meta-data
            android:name="com.google.android.gms.ads.APPLICATION_ID"
            android:value="***"/>
        <activity android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

I filled the android:value="***" with the app id which I made at AdMob.

There is no error in running app, but the Ad doesn't show up. At logcat I get a message below

I/Ads: Ad failed to load : 0

Also I get an error below

E/DynamiteModule: Failed to load IDynamiteLoader from GmsCore: Application package com.google.android.gms not found

How should I solve this problem? Sorry for duplicated or unnecessary codes.

Answer 1

Add this to your manifest

    <uses-permission android:name="android.permission.INTERNET"/>

And also this

<meta-data
        android:name="com.google.android.gms.ads.APPLICATION_ID"
        android:value="ca-app-pub-3940256099942544~3347511713" />