class Main3Activity: AppCompatActivity () {
private lateinit var auth: FirebaseAuth override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main3) auth = FirebaseAuth.getInstance() btn5_sign_up.setOnClickListener() { LoginActivity(Intent(this.SignUpActivity::class.java)) finish() } } public override fun onStart() { super.onStart() // Check if user is signed in (non-null) and update UI accordingly. var currentUser = auth.currentUser updateUI(currentUser) } //assigning the function previously named above fun updateUI (currentUser : FirebaseAuth?){ }
По сути, строка 7 не выполняет код go с красным на SignUpActivity
Используйте это
startActivity(Intent(this,SignUpActivity::class.java))
Вместо LoginActivity(Intent(this.SignUpActivity::class.java))
LoginActivity(Intent(this.SignUpActivity::class.java))