Android AdMob & Monetization — Banner, Interstitial, Rewarded

Monetization Overview

Google AdMob is the leading mobile ad platform for Android. It serves banner, interstitial, rewarded, and native ads — paying you when users view or click ads in your app.

Your Android App ↓ Google Mobile Ads SDK ↓ AdMob Ad Server → Advertisers ↓ Revenue (CPM / CPC) → Your AdMob Account

Ad Format	Appearance	Best For
Banner	Small strip at top/bottom	Continuous passive income
Interstitial	Full-screen between screens	Level transitions, natural breaks
Rewarded	Full-screen, user opts in	Extra lives, coins, premium content
Native	Matches app UI design	Feed lists, content screens

1AdMob Setup

Setting up AdMob involves creating an account, registering your app, adding the Mobile Ads SDK, and initializing it with your App ID before loading any ads.

Step-by-step setup

Create account at admob.google.com
Add your app → get App ID (format: ca-app-pub-XXXX~YYYY)
Create ad units for each format → get Ad Unit IDs
Add SDK dependency and initialize in Application class
Use test ad unit IDs during development

Gradle dependency

Kotlin — app/build.gradle.ktsdependencies {
    implementation("com.google.android.gms:play-services-ads:23.0.0")
}

AndroidManifest.xml

XML — AndroidManifest.xml<manifest>
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

    <application ... >
        <meta-data
            android:name="com.google.android.gms.ads.APPLICATION_ID"
            android:value="ca-app-pub-XXXXXXXXXXXXXXXX~YYYYYYYYYY" />
    </application>
</manifest>

Initialize Mobile Ads SDK

Kotlin — MyApplication.ktclass MyApplication : Application() {
    override fun onCreate() {
        super.onCreate()
        MobileAds.initialize(this) { initializationStatus ->
            Log.d("AdMob", "SDK initialized: ${initializationStatus.adapterStatusMap}")
        }
    }
}

Test ad unit IDs (development only)

Kotlin — Google test ad unitsobject TestAdUnits {
    const val BANNER = "ca-app-pub-3940256099942544/6300978111"
    const val INTERSTITIAL = "ca-app-pub-3940256099942544/1033173712"
    const val REWARDED = "ca-app-pub-3940256099942544/5224354917"
    const val NATIVE = "ca-app-pub-3940256099942544/2247696110"
}

2Banner Ads

Banner ads are rectangular ads displayed at the top or bottom of the screen. They remain visible while the user interacts with your app and are the simplest ad format to implement.

XML layout with AdView

XML — activity_main.xml<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <FrameLayout
        android:id="@+id/contentFrame"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1" />

    <com.google.android.gms.ads.AdView
        android:id="@+id/adView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom"
        app:adSize="BANNER"
        app:adUnitId="ca-app-pub-3940256099942544/6300978111" />
</LinearLayout>

Load banner in Activity

Kotlin — MainActivity.ktclass MainActivity : AppCompatActivity() {

    private lateinit var adView: AdView

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        adView = binding.adView
        adView.adListener = object : AdListener() {
            override fun onAdLoaded() {
                Log.d("AdMob", "Banner loaded")
            }
            override fun onAdFailedToLoad(error: LoadAdError) {
                Log.e("AdMob", "Banner failed: ${error.message}")
            }
        }
        adView.loadAd(AdRequest.Builder().build())
    }

    override fun onPause() {
        adView.pause()
        super.onPause()
    }

    override fun onResume() {
        super.onResume()
        adView.resume()
    }

    override fun onDestroy() {
        adView.destroy()
        super.onDestroy()
    }
}

Adaptive banner (recommended)

Kotlin — Adaptive banner sizefun loadAdaptiveBanner(adView: AdView, activity: Activity) {
    val adWidth = (activity.resources.displayMetrics.widthPixels
        / activity.resources.displayMetrics.density).toInt()

    val adSize = AdSize.getCurrentOrientationAnchoredAdaptiveBannerAdSize(activity, adWidth)
    adView.setAdSize(adSize)
    adView.loadAd(AdRequest.Builder().build())
}

Banner best practices

Place at bottom — less intrusive than top placement
Use adaptive banners for better fill rate on all screen sizes
Don't place banners over interactive UI elements
Pause/resume/destroy AdView with Activity lifecycle

3Interstitial Ads

Interstitial ads are full-screen ads shown at natural transition points — between levels, after completing a task, or when navigating between major screens. Preload them before showing.

Load and show interstitial

Kotlin — InterstitialAdHelper.ktclass InterstitialAdHelper(private val activity: Activity) {

    private var interstitialAd: InterstitialAd? = null

    fun loadAd(adUnitId: String) {
        InterstitialAd.load(
            activity,
            adUnitId,
            AdRequest.Builder().build(),
            object : InterstitialAdLoadCallback() {
                override fun onAdLoaded(ad: InterstitialAd) {
                    interstitialAd = ad
                    Log.d("AdMob", "Interstitial loaded")
                    setupCallbacks(ad)
                }

                override fun onAdFailedToLoad(error: LoadAdError) {
                    interstitialAd = null
                    Log.e("AdMob", "Interstitial failed: ${error.message}")
                }
            }
        )
    }

    private fun setupCallbacks(ad: InterstitialAd) {
        ad.fullScreenContentCallback = object : FullScreenContentCallback() {
            override fun onAdDismissedFullScreenContent() {
                interstitialAd = null
                loadAd(TestAdUnits.INTERSTITIAL)  // preload next
            }
            override fun onAdFailedToShowFullScreenContent(error: AdError) {
                interstitialAd = null
            }
        }
    }

    fun showAd() {
        interstitialAd?.show(activity) ?: run {
            Log.d("AdMob", "Interstitial not ready yet")
            loadAd(TestAdUnits.INTERSTITIAL)
        }
    }
}

Show at natural break points

Kotlin — Show after level completeclass GameActivity : AppCompatActivity() {

    private lateinit var interstitialHelper: InterstitialAdHelper

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        interstitialHelper = InterstitialAdHelper(this)
        interstitialHelper.loadAd(TestAdUnits.INTERSTITIAL)
    }

    private fun onLevelComplete() {
        showLevelCompleteDialog()
        interstitialHelper.showAd()  // natural break point
    }
}

Frequency capping

Kotlin — Limit ad frequencyclass AdFrequencyManager(context: Context) {
    private val prefs = context.getSharedPreferences("ad_prefs", Context.MODE_PRIVATE)

    fun canShowInterstitial(minIntervalMs: Long = 60_000): Boolean {
        val lastShown = prefs.getLong("last_interstitial", 0)
        return System.currentTimeMillis() - lastShown >= minIntervalMs
    }

    fun recordInterstitialShown() {
        prefs.edit().putLong("last_interstitial", System.currentTimeMillis()).apply()
    }
}

4Rewarded Ads

Rewarded ads let users opt in to watch a video ad in exchange for in-app rewards — extra lives, coins, or premium features. They have the highest engagement and eCPM of standard ad formats.

Load and show rewarded ad

Kotlin — RewardedAdHelper.ktclass RewardedAdHelper(private val activity: Activity) {

    private var rewardedAd: RewardedAd? = null

    fun loadAd(adUnitId: String) {
        RewardedAd.load(
            activity,
            adUnitId,
            AdRequest.Builder().build(),
            object : RewardedAdLoadCallback() {
                override fun onAdLoaded(ad: RewardedAd) {
                    rewardedAd = ad
                    Log.d("AdMob", "Rewarded ad loaded")
                }

                override fun onAdFailedToLoad(error: LoadAdError) {
                    rewardedAd = null
                    Log.e("AdMob", "Rewarded ad failed: ${error.message}")
                }
            }
        )
    }

    fun showAd(onRewardEarned: (Int) -> Unit) {
        val ad = rewardedAd
        if (ad == null) {
            Toast.makeText(activity, "Ad not ready. Try again.", Toast.LENGTH_SHORT).show()
            loadAd(TestAdUnits.REWARDED)
            return
        }

        ad.fullScreenContentCallback = object : FullScreenContentCallback() {
            override fun onAdDismissedFullScreenContent() {
                rewardedAd = null
                loadAd(TestAdUnits.REWARDED)
            }
        }

        ad.show(activity) { rewardItem ->
            Log.d("AdMob", "User earned: ${rewardItem.amount} ${rewardItem.type}")
            onRewardEarned(rewardItem.amount.toInt())
        }
    }
}

Reward button in UI

Kotlin — Watch ad for coinsclass ShopActivity : AppCompatActivity() {

    private lateinit var rewardedHelper: RewardedAdHelper
    private var coinBalance = 0

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        rewardedHelper = RewardedAdHelper(this)
        rewardedHelper.loadAd(TestAdUnits.REWARDED)

        binding.btnWatchAd.setOnClickListener {
            rewardedHelper.showAd { rewardAmount ->
                coinBalance += rewardAmount
                binding.tvCoins.text = "Coins: $coinBalance"
                Toast.makeText(this, "You earned $rewardAmount coins!", Toast.LENGTH_SHORT).show()
            }
        }
    }
}

Rewarded vs interstitial

Aspect	Interstitial	Rewarded
User choice	Shown automatically	User taps to watch
Engagement	Lower	Higher
eCPM (revenue)	Medium	Highest
Best use	Screen transitions	In-app currency, lives, unlocks
User sentiment	Can feel intrusive	Feels fair — user opts in

5App Monetization Strategies

Beyond ads, successful Android apps combine multiple revenue streams. Choose a strategy that matches your app category, user base, and retention goals.

Monetization models

Model	How It Works	Best For
Free + Ads	AdMob banner/interstitial/rewarded	Casual games, utility apps
Freemium	Free app, paid premium features	Productivity, fitness apps
In-App Purchases	Buy coins, remove ads, unlock content	Games, media apps
Subscription	Monthly/yearly recurring payment	Streaming, SaaS, news
Paid App	One-time purchase on Play Store	Pro tools, niche apps
Hybrid	Ads + IAP + subscription tiers	Most top-grossing apps

Hybrid strategy example

Free Tier Premium Tier ($4.99/mo) ───────── ────────────────────── Banner ads at bottom No ads Interstitial every 3 levels Unlimited levels Watch rewarded ad for coins 1000 coins/month included Basic features All features unlocked

Remove ads with in-app purchase

Kotlin — Hide ads for premium usersclass AdManager(private val context: Context) {

    private val prefs = context.getSharedPreferences("billing", Context.MODE_PRIVATE)

    fun isPremiumUser(): Boolean = prefs.getBoolean("is_premium", false)

    fun shouldShowAds(): Boolean = !isPremiumUser()

    fun setupBanner(adView: AdView) {
        if (shouldShowAds()) {
            adView.visibility = View.VISIBLE
            adView.loadAd(AdRequest.Builder().build())
        } else {
            adView.visibility = View.GONE
        }
    }
}

AdMob policy essentials

Never click your own ads or encourage users to click
Use test ad units during development — real clicks on test builds violate policy
Don't place ads too close to buttons (accidental clicks)
Disclose data collection in your privacy policy
Follow Google Play Families Policy if targeting children

Optimize revenue

Tip	Impact
Use rewarded ads for optional boosts	Higher eCPM, better UX
Enable AdMob mediation	More advertisers compete → higher bids
Cap interstitial frequency	Lower uninstall rate, better retention
A/B test ad placement	Find balance of revenue vs retention
Target tier-1 countries	Higher CPM in US, UK, CA, AU

6Hands-On Exercises

1

Complete AdMob setup — create account, add app, integrate SDK, initialize with test App ID.

2

Add an adaptive banner ad at the bottom of MainActivity. Handle pause/resume/destroy lifecycle.

3

Implement interstitial ads shown after completing a task. Preload the next ad after dismiss.

4

Add a "Watch Ad for Coins" button with rewarded ads. Grant in-app reward on completion.

5

Implement frequency capping — show interstitials no more than once per minute.

6

Build a premium toggle that hides all ads when the user "purchases" remove-ads (simulate with SharedPreferences).

7

Bonus: Write a monetization plan for a game app — choose ad formats, IAP items, and subscription tier.

AdMob & Monetization MCQ Practice

10 Basic MCQs 10 Advanced MCQs

10 Basic AdMob & Monetization MCQs

1

AdMob is?

ADatabase

BGoogle mobile advertising platform

CLayout editor

DKotlin compiler

Explanation: Monetize apps with banner, interstitial, rewarded ads.

2

App ID format?

AAPI-34

Bcom.example.app

Cca-app-pub-XXXX~YYYY

DSHA-256 only

Explanation: Declared in manifest meta-data APPLICATION_ID.

3

Banner ads are?

AIn-app purchase

BFull screen only

CVideo only

DRectangular ads at top or bottom

Explanation: Persistent small format while using app.

4

Interstitial ads show?

AFull-screen at natural breaks

BAlways on launch

CIn notification

DSQL query

Explanation: Between levels or screen transitions — preload first.

5

Rewarded ads give?

AFree premium forever

BUser reward after watching video ad

CRoot access

DNo SDK

Explanation: User opts in for coins, extra life, etc.

6

Test ad units during dev?

ANo ads in debug

BProduction IDs only

CGoogle sample ad unit IDs

DRandom IDs

Explanation: Avoid invalid traffic on your real ad units.

7

MobileAds.initialize?

ABanned API 34

BOptional

CReplaces manifest

DRequired before loading ads

Explanation: Call in Application onCreate.

8

AdView lifecycle?

Apause/resume/destroy with Activity

BIgnore lifecycle

COnce forever

DService only

Explanation: Prevent leaks and wasted impressions.

9

INTERNET permission for ads?

ANot needed

BRequired for ad network requests

CDangerous runtime

DCamera

Explanation: Normal permission in manifest.

10

eCPM means?

AAd size

BError code

CEffective cost per thousand impressions

DGradle metric

Explanation: Revenue metric — varies by region and format.

10 Advanced AdMob & Monetization MCQs

11

Adaptive banner?

AFixed 320x50 only

BWidth-matched banner for better fill rate

CInterstitial type

DRewarded

Explanation: AdSize.getCurrentOrientationAnchoredAdaptiveBannerAdSize.

12

UMP SDK purpose?

ARoom migration

BImage loading

CGDPR/consent messaging for ads

DCamera

Explanation: User Messaging Platform for consent in EEA/UK.

13

Ad failed to load LoadAdError?

AGradle sync

BIgnore always

CSuccess

DCheck network, ad unit ID, initialization, policy

Explanation: Log error code and message; retry with backoff.

14

Mediation in AdMob?

AMultiple ad networks compete in waterfall

BOne network only

CFree IAP

DFirebase Auth

Explanation: Increase fill rate and eCPM via mediation adapters.

15

App open ads?

ABanner only

BShown when user opens/resumes app

CSQL open

DDeprecated all

Explanation: Format for cold/warm start — use carefully for UX.

16

Invalid traffic risk?

ANo policy

BEncouraged in dev

CClicking your own ads gets account banned

DAutomatic money

Explanation: Never click production ads; use test devices.

17

Rewarded callback onUserEarnedReward?

ADelete data

BShow another ad

CCharge user

DGrant in-app reward here

Explanation: Verify reward amount/type; sync with game economy.

18

Native ads?

ACustom layout matching app UI with ad assets

BBanner only

CNo layout

DManifest

Explanation: NativeAdView binds headline, image, CTA.

19

Child-directed app ads?

ASame as gambling apps

BTag for Families policy — restricted ad behavior

CMore intrusive ads

DNo AdMob

Explanation: Design for Families compliance required.

20

Hybrid monetization?

AIAP banned

BAds only legal

CAds + IAP + subscriptions combined

DSubscriptions only Google

Explanation: Freemium: ads for free tier, remove ads via purchase.

Click an option to select, then check answers.

AdMob & Monetization Interview Q&A

15 topic-focused questions for interviews and revision.

1AdMob setup overview.easy

Answer: Create AdMob account, register app, add SDK, manifest App ID, initialize, create ad units, use test IDs in dev.

2Show banner ad steps.easy

Answer: AdView in layout, load AdRequest.Builder().build(), lifecycle pause/resume/destroy.

3Interstitial best practices.medium

Answer: Preload before show; natural breaks only; don't show on every click; reload after dismiss.

4Rewarded ad flow.medium

Answer: Load RewardedAd, show with callback, onUserEarnedReward grant benefit, onAdDismissed preload next.

5Why test ad units.easy

Answer: Prevent self-impression invalid activity on production ad units during development.

6GDPR consent with UMP.hard

Answer: Request consent info update; show form if required; pass consent to ad requests.

7Improve ad revenue ethically.medium

Answer: Good UX placement, mediation, rewarded opt-in, target correct audience, A/B test formats.

8AdMob vs Play Billing.medium

Answer: AdMob ads for free users; Billing for IAP/subscriptions — often combined.

9Handle no fill.medium

Answer: Hide ad container gracefully; retry load; consider mediation.

10Families policy apps.hard

Answer: Use Families ad SDK config; no personalized ads if required; content rating alignment.

11Track ad performance.easy

Answer: AdMob dashboard: impressions, eCPM, match rate; Firebase Analytics integration.

12Don't block UI with ads.easy

Answer: Async load; don't wait on main thread; show content first.

13App open ad caution.medium

Answer: Can annoy users if overused — cap frequency; skip if recent interstitial shown.

14Remove ads IAP pattern.medium

Answer: SharedPreferences flag adFree; hide AdView when purchased.

15Policy violations to avoid.hard

Answer: Encouraging clicks, deceptive placement, ads on lock screen without consent.

AdMob & Monetization

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