Activity flow: OnCreate called when I want to resume my activity

Question

My app requires people to log in with Facebook. Once they have done so, the Facebook token is checked each time they open the app so that we do not ask them to sign in again - we redirect them straight to the MainActivity .

Note that this is an 'empty view' activity - I have not used setContentView to set it to a view, it is purely there for decision making.

public class DecisionActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        FacebookSdk.sdkInitialize(getApplicationContext());

        if (AccessToken.getCurrentAccessToken() != null) {
                Intent intent = new Intent(this, MainActivity.class);
                startActivity(intent);
        } else {
            Intent startIntent = new Intent(this, SignUpActivity.class);
            startActivity(startIntent);
            finish();
        };
    }
}

This is my MainActivity code. Notice that I call my network operations in onCreate because I do not want to call them each time I minimize my app and maximize my app when the activity onResumes . It must be called once when I create my activity.

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //show my progress bar
        //CALL MY API TO GET SOME DATA FROM THE SERVER
        //hide my progress bar after data is received.
    }
}

This works perfectly. If the user has signed in, he is redirected to my MainActivity everytime. If the user hasn't signed in, he goes to SignUpActivity .

However, there is one nasty side effect from this code that I discovered today. Scenario 1 on onResuming my app works the way I want it to work. Scenario 2 on onResuming my app does not work the way I want it to work.

Scenario 1:

If you are in your MainActivity and you minimize your app and press the square button, find your app and maximize again, the MainActivity onCreate method will not be called as the activity simply onResumes therefore no network operations is performed, progress bar is not shown, which is what I want.

Scenario 2:

However, if you minimize your app and decide to click on the app icon on your phone, DecisionActivity will be launched which will decide that MainActivity needs to be launch as the user has logged in already and the token exists. Because MainActivity is relaunched, onCreate is called and network activities are performed and the progress bar is shown, which is not what I want.

How do I stop this from happening when I click on my app icon on my phone?

I checked popular apps like Facebook now to see if they have the same issue by testing Scenario 1 and Scenario 2 on them and they don't seem to encounter this problem which makes me think whether the setup I have used to check whether someone has logged into my app under DecisionActivity can be done in a better way.

Answer 1

I'm sure a more elegant way exists, but this is what I have off the top of my head:

Try using SharedPreferences. So, when your app is minimized, the onPause() method is called. In this method, set the SharedPreference to false, which means that you don't wanna run the progress bar right now. Check for that SharedPreference in your MainActivity's onCreate() method. When the app is resumed, set the SharedPreference to true.

So this means that whenever the user went through the onPause() method, the progress bar won't run either if he goes through the Scenario 1 (because then he will hit onResume(), which won't show the progress bar) or if he goes through Scenario 2 (because your SharedPreference is false, and you check for its value beforehand in MainActivity's onCreate()).

But, now you also have to use the onFinish() or the onDestroy() method, and change the value of your SharedPreference to true, which will make the progress bar to appear when the app is launched next time.

The only flaw I can think of is that I'm not sure whether the onDestroy() method would be called if the user closes the app from the Recents Menu, or if Android mamory cleaner closes the app to free up memory, so do try it and tell me if it works.

And I agree this is but more of a hack and not a proper solution, but if it works, it is good enough ;)