@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        progressBar = findViewById(R.id.progress);
        btnLogin = (Button) findViewById(R.id.btn_login);
        edit_email = (EditText) findViewById(R.id.edit_email);
        edit_password = (EditText)findViewById(R.id.edit_password);
        buttonAddUser = findViewById(R.id.button_add_user);
        setAddUserListener();
        setLoginListener();
    }