FireStore v3

private void UpdateData() {
        DocumentReference contact = db.collection("PhoneBook").document("Contacts");
        contact.update(NAME_KEY, "Kenny");
        contact.update(EMAIL_KEY, "kenny@gmail.com");
        contact.update(PHONE_KEY, "090-911-419")
                .addOnSuccessListener(new OnSuccessListener<Void>() {
            @Override
            public void onSuccess(Void aVoid) {
                Toast.makeText(MainActivity.this, "Updated Successfully",
                        Toast.LENGTH_SHORT).show();
            }
        });