Firebase database getInstance crashes app

[VihaanVerma89]

When running the sample after creating google-service.json the app crashes when trying to get database reference in SignInActivity

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

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) 

[VihaanVerma89]

http://stackoverflow.com/questions/37363791/firebase-database-getinstance-crashes-app?noredirect=1#comment62244072_37363791

[Polindem]

Caused by: com.google.firebase.database.DatabaseException: Failed to get FirebaseDatabase instance: Specify DatabaseURL within FirebaseApp or from your getInstance() call.

the URL should be inside of getInstance()

like:

FirebaseDatabase.getInstance("URL of your database here")