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

I have done this into my project and it is working perfectly, you can use this, you can use your phone number instead of "deviceId".

 mFirebaseDatabaseRefrence.orderByChild("deviceId").equalTo(deviceId).addListenerForSingleValueEvent(new ValueEventListener() {

            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                if (dataSnapshot.getValue() != null) {
                    Log.d(TAG, "Datasnap Shots: " + dataSnapshot.getValue());
                      /* if alredy exist and check for first time, second time isExist=true*/
                    if (!isExist) {

                        for (DataSnapshot userSnapshot : dataSnapshot.getChildren()) {
                            UserbasicInfo user = userSnapshot.getValue(UserbasicInfo.class);
                              Toast.makeText(UserInfoActivity.this, "User already exist...!", Toast.LENGTH_SHORT).show();

                        }

                    }
                    isExist = true;
                } else {
                    isExist = false;
                }
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        });

        /*if not exist add data to firebase*/
        Runnable runnable = new Runnable() {
            @Override
            public void run() {
                Log.d(TAG, "isExist: " + isExist);
                if (!isExist) {
                    addDataToDB(false);
                } else {
                    addDataToDB(true);

                }
            }
        };
        new Handler().postDelayed(runnable, 5000);