How can i remove first activity in the Activity Stack? [duplicate]

Question

I have 3 activities, A: LoginAcitivty, B: SignupActivity, C: HomeActivity and the flow is A -> B -> C. and if I signup in the SignupActivity, then I go to HomeActivity. but there is a problem. when I click the back button on my device. I can see the LoginActivity again. So i thought first, when i click the sign-up button, i go back to LoginActivity and then in the LoginActivity, i go to HomeActivity by using Intent for the HomeActivity. and also i wrote finish() in the LoginActivity. this is my code.

 <SignupActivity>
 val intent = Intent(this, LoginActivity::class.java)
        intent.putExtra("transfer", "transfer")
        startActivity(intent)
        finish()

 <LoginActivity>
 override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_login)

    if (intent.hasExtra("transfer")) {
        val intent = Intent(this, HomeActivity::class.java)
        startActivity(intent)
        finish()
    }
}

but it also doesn't work. when i click the back button on my device in the HomeActivity, i expected that the app will end. but i can still see the LoginActivity and i push back button again, then it's end. plz help me.

Answer 1

This is the default behavior of Android activities as your default launch mode of each of the activities is standard.

We can fix it in two ways. I will explain one way which is not bothering about the launch mode thing.

1. LoginActivity -> You should start the SignupActivity as

    activity.startActivityForResult(Intent(activity,SignupActivity::class.java), YOUR_REQUEST_CODE)
   
     override fun onActivityResult(requestCode: Int, resultCode: Int, 
                                                     data: Intent?) {
                if (requestCode == YOUR_REQUEST_CODE && resultCode == 
   RESULT_OK && data != null) {
                   // move to Home activity and `finish()` the current 
                   //login screen
            }
        }
   

2. LoginActivity -> You should start the HomeActivity if login success and finish() the login screen.