Android Firebase - cant get userid using getUid() - Error: on null object reference

Question

I am using Firebase and have a signup / login activities working fine but I also want each user to update a username. It seems I am unable to run:

firebaseR         


        

Answer 1

Need to add AuthStateListener.

        mAuth=FirebaseAuth.getInstance();
        mAuthListener=new FirebaseAuth.AuthStateListener() {
        @Override
        public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {


            if(firebaseAuth.getCurrentUser()==null){

               //Your action here

            }

        }
    };

Answer 2

A simple way to check if there is any update for Firebase dependency:

Answer 3

FirebaseAuth.getInstance().getUid(); This API seems to have been removed in Firebase 12.0.0

Use this instead FirebaseAuth.getInstance().getCurrentUser().getUid();

with the appropriate null check, or use Firebase 12.0.1 where i now seems to have @Hide annotation

Answer 4

• Add this after the Main Activity class

  Firebase firebaseAuth;
  DatabaseReference reference;
  

• Add anywhere in onCreate

  String usern;
  usern = firebaseAuth.getInstance().getCurrentUser().getUid();
  

• Upload to Firebase to their repective children

  reference=FirebaseDatabase.getInstance()
            .getReference().child("Patients")
            .child("Patient" + usern).child("Pres");
  

Answer 5

In your app build.gradle, add this to your dependencies

compile 'com.google.firebase:firebase-auth:9.4.0'

import com.google.firebase.auth.FirebaseAuth;
...
...

if (FirebaseAuth.getInstance().getCurrentUser() == null) {
    //Go to login 
}
else{
    String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();
}