CODEWITHSUNDEEP
javaandroidfirebase
Miljan Rakita
Miljan Rakita

Reputation: 1533

Android firebase onStart and onStop explanation

I've just started with firebase in android and i can't understand some things in onStart and in onStop.

Why is it necessary to have this code on stop method? Why do we need to remove listener ?

@Override
protected void onStop() {
    super.onStop();
    Log.d(TAG, "onStop: ");
    if(mAuthStateListener != null)
        mAuth.removeAuthStateListener(mAuthStateListener);
}

And one more question what is the advantage of setting up mAuth listener in onStart method instead of onCreate ?

@Override
protected void onStart() {
    super.onStart();
    Log.d(TAG, "onStart: ");
    mAuth.addAuthStateListener(mAuthStateListener);
}

This is how they shoved in Firebase -> Authentication demo.

Upvotes: 2

Views: 1706

Answers (1)

Sweeper
Sweeper

Reputation: 271410

There is the need to remove listeners because the mAuth will keep of keeping track of all the listeners you added, in order to notify you when something happens.

When the activity stops you remove the listener from the list because well, the activity has stopped anyway, there is no need to listen for auth events when the activity is stopped, is there?

Why add the listener at onStart then?

Because according to the activity life cycle:

enter image description here

onStart and onStop correspond to each other, while onCreate and onDestroy correspond to each other.

If you add the listener in onCreate and remove at onStop, the listener will not be added back when the activity restarts, since onCreate is not called on restart. onStart is.

Upvotes: 8

Related Questions