auth = FirebaseAuth.getInstance();

  if (auth.getCurrentUser() != null) {

       if(loginflag.equals("0")){
            startActivity(new Intent(LoginActivity.this, HomeUsers.class));
            finish();
        }
        else if (loginflag.equals("1"))  {
            startActivity(new Intent(LoginActivity.this, HomeEducator.class));
            finish();
           }
        }
    }


private void loginControl() {

    FirebaseUser user = auth.getCurrentUser();
    String id = user.getUid();
    DatabaseReference FirebaseRef = FirebaseDatabase.getInstance().getReference().child("users").child(id);

    FirebaseRef.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot snapshot) {

            if(snapshot.exists()){
                loginflag = snapshot.child("flag").getValue().toString();
            }
        }
        @Override
        public void onCancelled(DatabaseError databaseError) {
        }
    });
}