java.lang.IllegalStateException: Default FirebaseApp is not initialized in this process

java.lang.RuntimeException: Unable to create application com.ads.app.MyApplication: java.lang.IllegalStateException: Default FirebaseApp is not initialized in this process com.ads.app. Make sure to call FirebaseApp.initializeApp(Context) first.

Caused by: java.lang.IllegalStateException: Default FirebaseApp is not initialized in this process com.ads.app. Make sure to call FirebaseApp.initializeApp(Context) first.

1、检查项目\build.gradle

dependencies {

       classpath 'com.android.tools.build:gradle:3.2.1'

       classpath 'com.google.gms:google-services:4.2.0'

   }

2、检查google-services.json是否放在app\目录下,必须保证google-services.json里面有当前包的包名

3、检查app\build.gradle

dependencies {

   implementation 'com.google.android.gms:play-services-auth:15.0.1'

   implementation 'com.google.firebase:firebase-core:17.2.0'

   implementation 'com.google.firebase:firebase-iid:20.0.0'

   implementation 'com.google.firebase:firebase-messaging:20.0.0'

   implementation 'com.android.installreferrer:installreferrer:1.0'

}

apply plugin: 'com.google.gms.google-services'是否放在app\build.gradle底部

4、检查Application

@Override

   public void onCreate() {

       super.onCreate();

       FirebaseApp.initializeApp(this);

       initFirebase();

   }

private void initFirebase(){

       FirebaseInstanceId.getInstance().getInstanceId()

               .addOnCompleteListener(new OnCompleteListener<InstanceIdResult>() {

                   @Override

                   public void onComplete(@NonNull Task<InstanceIdResult> task) {

                       if (!task.isSuccessful()) {

                           MLog.e( "getInstanceId failed"+task.getException());

                           return;

                       }

                       String token = task.getResult().getToken();

                   }

               });

   }

5、检查AndroidManifest.xml，application是否被引用