Google Admob Interstitial Ads

In this tutorial, we will explore how to implement Google AdMob Interstitial Ads in our Android application using Kotlin. Interstitial ads are full-screen ads that cover the entire activity layout, providing an immersive experience for users. They are typically displayed at natural transition points in your app, such as between activities or after a user completes a task.

Understanding how to integrate ads into your app is crucial for developers who want to monetize their applications effectively. By learning this, you'll be able to enhance your app's functionality, potentially increasing revenue while providing users with relevant advertisements.

What Are Interstitial Ads?

Interstitial ads are ads that appear at a transition point in your application. They can be a great way to engage users while they are waiting for something to happen, such as loading the next screen.

When to Use Interstitial Ads

• ✅ Transition Points: Display them when users navigate from one screen to another.
• ✅ Task Completion: Show them after users finish a task or level (in games).
• ✅ Natural Breaks: Use them at moments when users are less engaged, ensuring it doesn't disrupt their experience.

Setting Up Google AdMob

Before we dive into the implementation, ensure you have the following:

1. AdMob Account: Sign up for an AdMob account and create a new app.
2. Ad Unit ID: Create an ad unit in your AdMob dashboard specifically for interstitial ads.

Adding Dependencies

You need to add the Google Mobile Ads SDK to your project. Open your build.gradle (Module: app) file and add the following line in the dependencies section:

dependencies {
    implementation 'com.google.android.gms:play-services-ads:20.6.0' // Use the latest version
}

Basic Syntax of AdMob Interstitial Ads

The following is the basic structure of how to implement interstitial ads:

1. Initialize the Mobile Ads SDK.
2. Create an InterstitialAd object.
3. Load an ad with a request.
4. Show the ad when it is ready.

Sample Code Structure

Example
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class MainActivity : AppCompatActivity() {
    private lateinit var interstitialAd: InterstitialAd

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        MobileAds.initialize(this) // Initialize Mobile Ads SDK
        loadInterstitialAd()
    }

    private fun loadInterstitialAd() {
        val adRequest = AdRequest.Builder().build()
        InterstitialAd.load(this, "YOUR_AD_UNIT_ID", adRequest, object : InterstitialAdLoadCallback() {
            override fun onAdLoaded(ad: InterstitialAd) {
                interstitialAd = ad
                // Show ad when ready
                interstitialAd.show(this@MainActivity)
            }

            override fun onAdFailedToLoad(adError: LoadAdError) {
                // Handle the error
            }
        })
    }
}
Try it Yourself

Detailed Walkthrough with Examples

Example 1: Basic Interstitial Ad Implementation

Let's create a simple app that displays an interstitial ad when a button is clicked.

Step 1: Update `activity_main.xml`

Create a simple layout with a button to load the ad.

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <Button
        android:id="@+id/load_ad_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Load Ad"
        android:layout_centerInParent="true" />
</RelativeLayout>

Step 2: Update `MainActivity.kt`

package com.example.admobinterstitial

import android.os.Bundle
import android.widget.Button
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import com.google.android.gms.ads.AdRequest
import com.google.android.gms.ads.InterstitialAd
import com.google.android.gms.ads.interstitial.InterstitialAdLoadCallback
import com.google.android.gms.ads.LoadAdError
import com.google.android.gms.ads.MobileAds

class MainActivity : AppCompatActivity() {
    private lateinit var interstitialAd: InterstitialAd

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        MobileAds.initialize(this) // Initialize Mobile Ads SDK
        loadInterstitialAd()

        findViewById<Button>(R.id.load_ad_button).setOnClickListener {
            showInterstitialAd()
        }
    }

    private fun loadInterstitialAd() {
        val adRequest = AdRequest.Builder().build()
        InterstitialAd.load(this, "YOUR_AD_UNIT_ID", adRequest, object : InterstitialAdLoadCallback() {
            override fun onAdLoaded(ad: InterstitialAd) {
                interstitialAd = ad
                Toast.makeText(this@MainActivity, "Ad Loaded", Toast.LENGTH_SHORT).show()
            }

            override fun onAdFailedToLoad(adError: LoadAdError) {
                Toast.makeText(this@MainActivity, "Ad Failed to Load", Toast.LENGTH_SHORT).show()
            }
        })
    }

    private fun showInterstitialAd() {
        if (::interstitialAd.isInitialized) {
            interstitialAd.show(this)
        } else {
            Toast.makeText(this, "Ad not loaded yet", Toast.LENGTH_SHORT).show()
        }
    }
}

Expected Output:

When the button is clicked, an interstitial ad should display (if it has been loaded successfully).

Example 2: Handling Ad Events

In this example, we will build upon the first example and handle the events when the ad is closed.

Update `MainActivity.kt`

private fun loadInterstitialAd() {
    val adRequest = AdRequest.Builder().build()
    InterstitialAd.load(this, "YOUR_AD_UNIT_ID", adRequest, object : InterstitialAdLoadCallback() {
        override fun onAdLoaded(ad: InterstitialAd) {
            interstitialAd = ad
            interstitialAd.fullScreenContentCallback = object : FullScreenContentCallback() {
                override fun onAdDismissedFullScreenContent() {
                    Toast.makeText(this@MainActivity, "Ad was dismissed", Toast.LENGTH_SHORT).show()
                    loadInterstitialAd() // Load a new ad
                }

                override fun onAdFailedToShowFullScreenContent(adError: AdError) {
                    Toast.makeText(this@MainActivity, "Ad failed to show", Toast.LENGTH_SHORT).show()
                }

                override fun onAdShowedFullScreenContent() {
                    interstitialAd = null // Set to null to indicate it’s shown
                    Toast.makeText(this@MainActivity, "Ad was shown", Toast.LENGTH_SHORT).show()
                }
            }
            Toast.makeText(this@MainActivity, "Ad Loaded", Toast.LENGTH_SHORT).show()
        }

        override fun onAdFailedToLoad(adError: LoadAdError) {
            Toast.makeText(this@MainActivity, "Ad Failed to Load", Toast.LENGTH_SHORT).show()
        }
    })
}

Expected Output:

When the ad is shown, you will see a toast message indicating the ad was shown. When dismissed, it will load a new ad.

Example 3: Integrating with Game Levels

In gaming applications, you might want to show interstitial ads after completing a level.

Here’s how you could modify the code to show an ad after completing a level:

private fun completeLevel() {
    // Code to complete the level
    showInterstitialAd() // Show ad after level completion
}

Expected Output:

After completing a level, the interstitial ad will be displayed.

Common Mistakes

1. Not Handling Ad Lifecycle:

• ✅ Failing to reload ads after dismissal can lead to a poor user experience. Always load a new ad when the previous one is closed.

1. Using Invalid Ad Unit IDs:

• ✅ Make sure to use the correct ad unit ID. Using an invalid one will lead to ads not loading.

1. Not Checking Ad State:

• ✅ Always check if the ad is loaded before attempting to show it. This prevents crashes and improves user experience.

Best Practices

• ✅ Test Ads: Use test ads during development to avoid policy violations. AdMob provides test ad unit IDs.
• ✅ User Experience: Be considerate about when to show ads. Avoid showing them during critical interactions to maintain a good user experience.
• ✅ Data Privacy: Follow all guidelines regarding user data and privacy, especially if your app targets children.

Practice Exercises

1. Create a Button to Load Ads: Implement a feature where users can load a new ad by clicking a different button.
2. Show Ads after Specific Events: Modify the app to show ads after completing a specific action (like finishing a game level).
3. Display Message on Ad Load Failure: Enhance the app to provide more detailed error messages when an ad fails to load.

By practicing these exercises, you'll deepen your understanding of how to work with interstitial ads in Kotlin for Android applications. Happy coding!