Firebase Assistant：实时数据库

Question

I'm new at android developing. Here's my code that I copied on the firebase assistant

import android.nfc.Tag;
import android.util.Log;

import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.ValueEventListener;

public class FirebaseDB {
    DatabaseReference myRef = FirebaseDatabase.getInstance().getReference();

    myRef.addValueEventListener(new ValueEventListener(){
        @Override
        public void onDataChange(DataSnapshot dataSnopshot){
            String value = dataSnopshot.getValue(String.class);
            Log.d(Tag, "Value is: " + value);
        }

       @Override
       public void onCancelled(DatabaseError error) {
           Log.w(Tag, "Failed to read value.", error.toException());
       }
   });
}

I'm using android studio 2.3.3

My problem is that, the myRef.addValueEventListener became error though myRef is a DatabaseReference which inherit Query class. I tried DatabaseReference myRef = new DatabaseReference(); still got me an error, also the new ValueEventListener() , DataSnopshot dataSnopshot and DatabaseError error , same also for the Tag

Here's for the build.gradle, and the firebase assistant

Thanks for the help.

Answer 1

This looks like a firebase and appcompat dependency issue. firebase 10.0.2 is very old now. The latest version is

compile 'com.google.firebase:firebase-database:11.2.2

Also you buildtools version is 26, which conflicts with your targetsdk version 24

Answer 2

Could be that your errors are caused by sdk tools and libraries conflicts in your gradle. So try to update your support libraries versions to latest which is currently 26.0.0-alpha1 or at least 25.3.1 .

For example compile 'com.android.support:appcompat-v7:25.3.1'

Then update your firebase dependencies to latest version 11.2.2 .

Note: after upgrading firebase libraries there are some new rules

• your compileSdkVersion must be 26 also upgrade your targetSdkVersion to 26
• inside your build gradle add path for your dependencies which are now directly available on maven.google.com like this:

allprojects { repositories { jcenter() maven { url 'https://maven.google.com' } } }

For more see on: https://firebase.googleblog.com/2017/08/some-updates-to-apps-using-google-play.html