Firebase getInstance Database Disables Application

Question

When you run the sample after creating google-service.json, the application crashes when you try to get a link to the database in SignInActivity

mDatabase = FirebaseDatabase.getInstance().getReference(); 

Crash log

 05-21 09:27:27.644 488-488/com.google.firebase.quickstart.database D/AndroidRuntime: Shutting down VM 05-21 09:27:27.644 488-488/com.google.firebase.quickstart.database E/AndroidRuntime: FATAL EXCEPTION: main Process: com.google.firebase.quickstart.database, PID: 488 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.google.firebase.quickstart.database/com.google.firebase.quickstart.database.SignInActivity}: com.google.firebase.database.DatabaseException: Failed to get FirebaseDatabase instance: FirebaseApp object has no DatabaseURL in its FirebaseOptions object. at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2325) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387) at android.app.ActivityThread.access$800(ActivityThread.java:151) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:135) at android.app.ActivityThread.main(ActivityThread.java:5254) at java.lang.reflect.Method.invoke(Native Method) at java.lang.reflect.Method.invoke(Method.java:372) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698) Caused by: com.google.firebase.database.DatabaseException: Failed to get FirebaseDatabase instance: FirebaseApp object has no DatabaseURL in its FirebaseOptions object. at com.google.firebase.database.FirebaseDatabase.getInstance(Unknown Source) at com.google.firebase.database.FirebaseDatabase.getInstance(Unknown Source) at com.google.firebase.quickstart.database.SignInActivity.onCreate(SignInActivity.java:39) at android.app.Activity.performCreate(Activity.java:5990) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387) at android.app.ActivityThread.access$800(ActivityThread.java:151) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:135) at android.app.ActivityThread.main(ActivityThread.java:5254) at java.lang.reflect.Method.invoke(Native Method) at java.lang.reflect.Method.invoke(Method.java:372) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698) 

How to fix this problem?

Answer 1

Download google-services.json from Project Settings in the Firebase console . My mistake was downloading it from https://developers.google.com/mobile/add .

Answer 2

mFirebaseDatabaseReference = database.getInstance().getReference("root-element in firebase");

When you call getReference , you need to provide a url. If your project is already connected in Firebase to the database you created, use the root data element in Firebase as the getReference() parameter.