Android Studio: App crashes after adding Firebase

Question

I've tried soo much searching for a solution but there's no solution that sovled my problem!

My app works fine but I want to add the result in the TextView to a Firebase. After I add the Firebase to my Java code, app crashes with the message "App Unfotunatlly stopped" and I open the app on a real device!

Here's my Java code with the added Firebase:

public class MainActivity extends AppCompatActivity implements LocationListener ,ValueEventListener {

//here is the added firebase that cause the error -_-
FirebaseDatabase database = FirebaseDatabase.getInstance();
private DatabaseReference myRef = database.getReference();
private DatabaseReference buslocationRef = myRef.child("master");

Button getLocationBtn;
TextView locationText, test1;

LocationManager locationManager;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    getSupportActionBar().hide();
    setContentView(R.layout.activity_main);
...........................

}
}

and my build.gradle :

dependencies {

compile 'com.android.support:appcompat-v7:26.1.0'

compile 'com.google.firebase:firebase-database:12.0.1'
}

plus, I've updated my Android Studio to the latest version 3.0!!

I hope you can help me with this. Thanks in Advance.

Answer 1

尝试在build.gradle（项目版本）中将google-services版本更改为4.2.0。