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

DatabaseReference userRef = FirebaseDatabase.getInstance().getReference("Users");
userRef
    .orderByChild("phonenumber")
    .equalTo(mMobile.getText().toString())
    .addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            if (dataSnapshot.getValue() != null) {
                //it means user already registered
                //Add code to show your prompt
                OpenErrorAlrt("Mobile Number already registed");
            } else {
                Intent intent = new Intent(getApplicationContext(), OTPVerifyActivity.class);
                intent.putExtra("phonenumber", mMobile.getText().toString());
                startActivity(intent);
            }

        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });