Android Studio (kotlin) - User Has To Log Back Into App Every Time App Is Closed

So i have a RegisterActivity and a MapsActivity. When a new user opens the app, they will be on the RegisterActivity and sign up. Once they sign up, my app creates an Intent and se

Solution 1:

The simplest way to achieve this is to use a listener. Let's assume you have two activities, the LoginActivity and the MainActivity. The listener that can be created in the LoginActivity should look like this:

val authStateListener = FirebaseAuth.AuthStateListener { firebaseAuth ->
    val firebaseUser = firebaseAuth.currentUser
    if (firebaseUser != null) {
        val intent = Intent(this, MainActivity::class.java)
        startActivity(intent)
        finish()
    }
}

This basically means that if the user is logged in, skip the LoginActivity and go to the MainActivity.

Instantiate the FirebaseAuth object:

valfirebaseAuth= FirebaseAuth.getInstance()

And start listening for changes in your onStart() method like this:

overridefunonStart() {
    super.onStart()
    firebaseAuth!!.addAuthStateListener(this.authStateListener!!)
}

In the MainActivity, you should do the same thing:

val authStateListener = FirebaseAuth.AuthStateListener { firebaseAuth ->
    val firebaseUser = firebaseAuth.currentUser
    if (firebaseUser == null) {
        val intent = Intent(this, LoginActivity::class.java)
        startActivity(intent)
    }
}

Which basically means that if the user is not logged in, skip the MainActivity and go to the LoginActivity. In this activity you should do the same thing as in the LoginActivity, you should start listening for changes in the onStart().

In both activities, don't forget to remove the listener in the moment in which is not needed anymore. So add the following line of code in your onStop() method:

overridefunonStop() {
    super.onStop()
    firebaseAuth!!.removeAuthStateListener(this.authStateListener!!)
}

Solution 2:

I have developer a similar app and I simply use a splash screen that checks if the users is logged or not and then open the right screen. The splash doesn't need to be to complex: in fact you can even avoid to set a view and just check whatever you want. This article explains it very clearly.

Remember to call finish() on the splash activity after launching the right one.