Firebase - How to check whether a user has already signed up using Phone Number

Question

I am using firebase phone Authentication . When a user creates a account using phone number and next time he creates account with same phone number Than I want to show a m

Answer 1

This is very easy way to check whether a user is already register with firebase.

 AuthCredential credential = GoogleAuthProvider.getCredential(acct.getIdToken(), null);
    mAuth.signInWithCredential(credential)
            .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
                @Override
                public void onComplete(@NonNull Task<AuthResult> task) {
                    if (task.isSuccessful()) {
                        // Sign in success, update UI with the signed-in user's information
                        Log.d(TAG, "signInWithCredential:success");
                        FirebaseUser user = mAuth.getCurrentUser();
                        if(task.getResult().getAdditionalUserInfo().isNewUser()){
                            register(user);
                        }else{
                            Intent intent = new Intent(LoginActivity.this,MainActivity.class);
                            startActivity(intent);
                        }
                        Toast.makeText(LoginActivity.this, "welcome"+user.getDisplayName(), Toast.LENGTH_SHORT).show();
                    } else {
                        // If sign in fails, display a message to the user.
                        Log.w(TAG, "signInWithCredential:failure", task.getException());
                        Toast.makeText(LoginActivity.this, "signin Failed", Toast.LENGTH_SHORT).show();
                    }

                    // ...
                }
            });