如何加载RewardedAd？

我遵循了同一教程，并检查了您的代码，这似乎是正确的，以防万一您想再次检查！在您按下载入按钮后，请尝试按几次显示按钮，因为有时广告会花费一些时间来载入。并且不要忘记从activity_main.xml设置按钮onClick函数。

这是MainActivity：

  public class MainActivity extends AppCompatActivity {

    private RewardedAd rewardedAd;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        MobileAds.initialize(this, new OnInitializationCompleteListener() {
            @Override
            public void onInitializationComplete(InitializationStatus initializationStatus) {

            }
        });
    }

    public void showAd(View view) {

        if(this.rewardedAd.isLoaded()){

            RewardedAdCallback callback = new RewardedAdCallback() {
                @Override
                public void onUserEarnedReward(@NonNull RewardItem rewardItem) {
                   Log.i("MainActivity","Got Reward");
                }

                @Override
                public void onRewardedAdOpened() {
                    super.onRewardedAdOpened();
                        Log.i("MainActivity","Opened");
                }

                @Override
                public void onRewardedAdClosed() {
                    super.onRewardedAdClosed();
                    Log.i("MainActivity","Closed");
                }

                @Override
                public void onRewardedAdFailedToShow(int i) {
                    super.onRewardedAdFailedToShow(i);
                    Log.i("MainActivity","Failed to show");
                }
            };
            this.rewardedAd.show(this,callback);

        }
        else{
            Log.i("MainActivity","Not Loaded");
        }
    }

    public void loadAd(View view) {

        this.rewardedAd = new RewardedAd(this,"ca-app-pub-3940256099942544/5224354917");
        RewardedAdLoadCallback callback = new RewardedAdLoadCallback(){
            @Override
            public void onRewardedAdFailedToLoad(int i) {
                super.onRewardedAdFailedToLoad(i);
                Log.i("MainActivity","Failed");
            }

            @Override
            public void onRewardedAdLoaded() {
                super.onRewardedAdLoaded();
                Log.i("MainActivity","Loaded");
            }
        };

        this.rewardedAd.loadAd(new AdRequest.Builder().build(),callback);
    }
}

这是Android清单：

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

        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

</manifest>

这是问题：

apply plugin: 'com.android.application'

android {
    compileSdkVersion 29
    buildToolsVersion "29.0.2"
    defaultConfig {
        applicationId "jalaleddine.abdelbasset.admobtest"
        minSdkVersion 19
        targetSdkVersion 29
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'androidx.appcompat:appcompat:1.1.0'
    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
    testImplementation 'junit:junit:4.12'
    implementation 'com.google.android.gms:play-services-ads:18.2.0'
    androidTestImplementation 'androidx.test.ext:junit:1.1.1'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
}