How to run code on Application opens in Android?

Question

My Android app need the user to create an account to be able to use the app. The account info is stored in SQLite database. When the application starts I check if the user has an account, if not I show a sign up activity for the user.

Now I get reports from users that they sometimes comes to the sign up activity even if they've already created an account. This happens when they've closed the application and reopen it again.

This is the code I'm using and I need to figure out what the problem might be:

//MyApplication.java
public class MyApplication extends Application {
    private DataBaseUtility dbu;
    public boolean hasAccount;  

    @Override
    public void onCreate() {
        super.onCreate();

        //Init sqlite database
        this.dbu = new DataBaseUtility(this);

        //This loads the account data from the database and returns true if the user has already created an account
        this.hasAccount = loadAccount();
    }

    public boolean loadAccount() {
        boolean loadedData = false;

        String query = "SELECT data FROM tblaccount WHERE tblaccount.deleted=0";
        Cursor cursor = this.dbu.getCursor(query);
        if (cursor != null) {
            while (cursor.moveToNext()) {
                loadedData = true;
            }
            cursor.close();
        }

        return loadedData;
    }
}

//MainActivity.java
public class MainActivity extends TabActivity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        MyApplication application = (MyApplication)getApplication();
        if (!application.hasAccount) {
            //Take the user to the sign up activity
        }
}

My idea is that maybe sometimes MainActivity.onCreate() runs before MyApplication.onCreate(). Can that be the case?

Answer 1

In application's onCreate, you are checking if the user has an account and setting a boolean.

You are checking in the MainActivity's onCreate if the user has an account through the application's boolean.

application's onCreate() executing before MainActivity's onCreate() is always the case! It is impossible for a different execution path to occur and since application's onCreate() does not have a Runnable it is a 100% garantuee.

Please make sure you're DataBaseUtility does not have any Runnables.

Anyway STILL there are several ways to reproduce the error! I will not state these now but you can know them when you see:

SOLUTION

MainActivity You have forgotten to update application.hasAccount upon successfull sign up~

public class MainActivity extends TabActivity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        MyApplication application = (MyApplication)getApplication();
        if (!application.hasAccount) {
            //Take the user to the sign up activity
            //if(successful) application.hasAccount = true
        }
}

To avoid database exceptions

I use this:

REMARK It would be much better to use more strong persistent status saving for the database -i.e. SharedPreferences

boolean isOpened = false;
//When I need to open
if(!isOpened){
    //open
    isOpened = true;
}
//When I need to close
if(isOpened){
    //close
    isOpened = false;
}

onDestroy() {  //every onDestroy
    if(isOpened){
        //close
    }
}