每次返回 MainActivity 时 AlertDialog 都会重新启动

Question

I created a MainActivity in which the user has a few app options, displayed in a grid menu, which access subsequent specific activities. However, when the application starts, I use an AlertDialog for the user to enter login details, inflated just after the grid layout definition. The problem is, each time I select an item in the grid menu (and, consequently, a new activity), the AlertDialog pops-up again. How can I avoid this?

Moreover, I have an uploading service which should start with the beginning of the MainActivity (or after the login, perhaps), but should not be restarted each time a new activity is called. I assume this problem is related to the previous one, although I have managed to temporarily solve it by using a startService button via an OptionsMenu. This is no permanent solution.

Thank you in advance.

EDIT: I tried to use getSharedPreferences as follows:

private SharedPreferences prefs;
private String prefName = "MyPref";
int hasLoggedIn;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.mm_gridmenu);

    SharedPreferences prefs = getSharedPreferences(prefName, MODE_PRIVATE);
    hasLoggedIn = prefs.getInt("hasLoggedIn", 0);

    if (hasLoggedIn == 0) {
        showDialog(SHOW_DIALOG);
        prefs = getSharedPreferences(prefName , MODE_PRIVATE);
        SharedPreferences.Editor editor = prefs.edit();
        editor.putInt("hasLoggedIn", 1);
        editor.commit();
    }

However, this way the hasLoggedIn value is saved as 1 and the dialog never pops-up again. I tried setting the back button to fix that, but this seems to prevent the app from being minimized. Is there a way to add that action to the button? (Which I would duplicate on the Home button as well)

@Override
public void onBackPressed() {
    prefs = getSharedPreferences(prefName , MODE_PRIVATE);
    SharedPreferences.Editor editor = prefs.edit();
    editor.putInt("hasLoggedIn", 0);
    editor.commit();
    Log.i("hasLoggedIn", hasLoggedIn + "");
    return;
}

Moreover, I believe this action will affect subsequent activities (setting the alertDialog back on). Which should be a valid alternative to this?

Answer 1

Basically you need to keep track of your applications states, you have a few options to do this. One simple way would be to use a SharedPreferences to store a boolean variable called something like hasLoggedIn after the user logs in you set this value to true . Each time your main activity launches simply check the value of hasLoggedIn if its is set to false require the user log in again. If it is already true don't show the log in dialog

Answer 2

You can try this: Add a boolean flag in your MainActivity:

private boolean dialogFlag = true;

in the onCreate/onResume method:

if(dialogFlag) {
    createDialog();
    dialogFlag = false;
}

If you want to pop up just once the app is installed, you can save this flag into a property file. And read it first whenever the app is getting started.