java.lang.ClassNotFoundException:找不到类“com.google.android.gms.ads.MobileAdsInitProvider"

I am facing this issue in Android Version 4.4 and below. I have integrated Google admob and when I run the app, the app crashes with ClassNotFoundException.

Please find the stacktrace below.

Process: app.learnkannada.com.learnkannadakannadakali, PID: 1320
java.lang.RuntimeException: Unable to get provider com.google.android.gms.ads.MobileAdsInitProvider: java.lang.ClassNotFoundException: Didn't find class "com.google.android.gms.ads.MobileAdsInitProvider" on path: DexPathList[[zip file "/data/app/app.learnkannada.com.learnkannadakannadakali-2.apk"],nativeLibraryDirectories=[/data/app-lib/app.learnkannada.com.learnkannadakannadakali-2, /system/lib]]
    at android.app.ActivityThread.installProvider(ActivityThread.java:4793)
    at android.app.ActivityThread.installContentProviders(ActivityThread.java:4385)
    at android.app.ActivityThread.handleBindApplication(ActivityThread.java:4325)
    at android.app.ActivityThread.access$1500(ActivityThread.java:135)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
    at android.os.Handler.dispatchMessage(Handler.java:102)
    at android.os.Looper.loop(Looper.java:136)
    at android.app.ActivityThread.main(ActivityThread.java:5017)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:515)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
    at dalvik.system.NativeStart.main(Native Method)
 Caused by: java.lang.ClassNotFoundException: Didn't find class "com.google.android.gms.ads.MobileAdsInitProvider" on path: DexPathList[[zip file "/data/app/app.learnkannada.com.learnkannadakannadakali-2.apk"],nativeLibraryDirectories=[/data/app-lib/app.learnkannada.com.learnkannadakannadakali-2, /system/lib]]
    at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:497)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:457)
    at android.app.ActivityThread.installProvider(ActivityThread.java:4778)
    at android.app.ActivityThread.installContentProviders(ActivityThread.java:4385) 
    at android.app.ActivityThread.handleBindApplication(ActivityThread.java:4325) 
    at android.app.ActivityThread.access$1500(ActivityThread.java:135) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256) 
    at android.os.Handler.dispatchMessage(Handler.java:102) 
    at android.os.Looper.loop(Looper.java:136) 
    at android.app.ActivityThread.main(ActivityThread.java:5017) 
    at java.lang.reflect.Method.invokeNative(Native Method) 
    at java.lang.reflect.Method.invoke(Method.java:515) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) 
    at dalvik.system.NativeStart.main(Native Method) 

I have tried looking on google but couldn't find this problem. Requesting the community to please help on this.

Note: Please note that I have already added mobile ads meta-data in Android Manifest already.

解决方案

You are getting this error because you have use multiDex but some implementation part is missing. Follow below steps to resolve the error.

1) Add "multiDexEnabled true" in defaultconfig in app-level gradle file

android {
    defaultConfig {
        ...
        minSdkVersion 21
        targetSdkVersion 28
        multiDexEnabled true
    }
    ...
}

2) If your minSdkVersion is less than 21 then add below dependency.

dependencies {
  implementation 'com.android.support:multidex:1.0.3'
}

3) Use MultiDexApplication class as Application class. There are three way to use MultiDexApplication as Application class

i) Just set MultiDexApplication class in AndroidManifest.xml file

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.myapp">
    <application
            android:name="android.support.multidex.MultiDexApplication" >
        ...
    </application>
</manifest>

ii) If you are already using custom application class then extent MultiDexApplication in custom application class

public class MyApplication extends MultiDexApplication { ... }

iii) If it is not possible to extend MultiDexApplication because you already extend other class and can not change it then use below method in your custom application class

public class MyApplication extends SomeOtherApplication {
  @Override
  protected void attachBaseContext(Context base) {
     super.attachBaseContext(base);
     MultiDex.install(this);
  }
}

Note: I was facing same error and just solved by extending MultiDexApplication class