android-how to make a login?

Question

I've some information in my application , it's my company information . I want to make a login every time app closes and runs .

this is what i've done so far . I make a custom dialog with user and password field . The problem is this , every time I rotate the screen or I come to MainActivity , I need to re login and it's bothering alot .

I want this dialog comes up every time I close the app and run it again , just that . I've tried onStop and onDestory but when I rotate the screen or change the activity and leave mainactivity , it show me this dialog .

How can I show the dialog only the first time app runs and if I close the app and run it again ,it asks me to login again ?

thanks

Use shared preferences to store login information and then clear the shared preferences once the use exits the app — Soumil Deshpande, Jun 02 '14 at 12:35
@SoumilDeshpande how I clear sharedPrefences on Exit ?what is the class that runs when the application is about to close ? this is the problem — user3699339, Jun 02 '14 at 14:28

score 0 · Accepted Answer · edited May 23 '17 at 12:05

On orientation change, all life cycle functions of the Activity are called, because it is reconstructed from zero. Your application must take this into account. The current activity goes onPause() onStop() onDestroy(), then the new Activity goes onCreate() onStart() onResume(), in that order.

Therefore you must store the fact that you have logged in, in such a way that the application does not forget. Peristent data storage can be done with SharedPreferences for example, if you don't want to use anything more complicated. Check out Android getDefaultSharedPreferences for this.

What you could probably do (but it seems like a haxory solution rather than a good one) is that in the onSaveInstanceState(Bundle bundle) function you save out the current value of the boolean that indicates being logged in into the Bundle, and then in onDestroy() you set it to false in the SharedPreferences. In the onCreate(Bundle bundle) function, if the Bundle isn't null, then update the SharedPreferences' boolean according to the Bundle's content. If the user is "logged in" according to the boolean, don't display the dialog.

score 0 · Answer 2 · answered Jun 02 '14 at 12:45

You could the store login state using savedInstanceState

private static final String BUNDLE_IS_LOGGED_IN = "isLoggedIn";

private boolean isLoggedIn = false; // Set this to true when you log in

@Override
protected void onSaveInstanceState(Bundle outstate) {
    outstate.putBoolean(BUNDLE_IS_LOGGED_IN, isLoggedIn);
}

@Override 
protected void onCreate(Bundle savedInstanceState) {
    if (savedInstanceState != null) {
        isLoggedIn = savedInstanceState.getBoolean(BUNDLE_IS_LOGGED_IN, false);
    }

    if (!isLoggedIn) {
        // Make user log in
    }
}

This means that on orientation change, or if the activity is re-created after the system chooses to destroy it, you will still be logged in. If, however, the user exits the application of their own accord (e.g. by pressing the back button), then they will be logged out.

It also means that you don't need to store the user's log in details anywhere.

thanks for the reply , so I need to remove this information when the application closed . How to remove this information when the application is closed? — user3699339, Jun 02 '14 at 14:29
It will automatically remove it for you. The `savedInstanceState` param in `onCreate` will only be non-null if the activity is re-created (e.g. due to orientation change, or being killed by the system due to low memory). If the activity is exited by the user, savedInstanceState will be set to null automatically. Hope that helps — user184994, Jun 02 '14 at 14:35

android-how to make a login?

2 Answers2