onPostExecute() not related to doInBackground() while debugging

Issue

I have a problem with my onPostExecute() method in AsyncTask class.

I have an SignupActivity:

public class SignupActivity extends AppCompatActivity implements SignupListener {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.signup_activity);

    //new task, i pass context and interface to it
    signup = new Signup(getApplicationContext(), this);

    signupButon.setOnClickListener(new View.OnClickListener(){
        @Override
        public void onClick(View v){
            if(validate()) {
                try {
                    //new task every click
                    Signup newSignup = new Signup(signup);
                    //here start AsyncTask
                    newSignup.execute(name, email, password).get();
                } catch (Exception e) {
                    Toast.makeText(ERROR);
                }
                // if sign up succes, == true;
                if(signupValid) {
                    Toast.makeText(SUCCES);
                    finish();
                } else {
                    Toast.makeText(ERROR);
                }
            }
        }
    });
}

// my own interface for getting result as bool from onPostExecute
@Override
public void onSignupPerformed(Boolean result){ this.signupValid = result; }

That implements my interface to catching result from onPostExecute():

public interface SignupListener{
    void onSignupPerformed(Boolean result);
}

Now, AsyncTask that i trigger in code:

public class Signup extends AsyncTask<String,  Boolean, Boolean> {

public Signup(Context context, SignupListener listener){
    db = ApplicationDatabase.getDatabase(context);
    this.context = context;
    this.listener = listener;
}

public Signup(Signup signup){
    //constructor to make new task based on first task
    db = signup.db;
    context = signup.context;
    listener = signup.listener;
}

protected Boolean doInBackground(String... body){
    try {
            user = db.userDao().getUser(body[0], body[1], body[2]);
            if (user == null) {
                // user is null, so we can add new one to DB
                db.userDao().insertUser(new User(body[0], body[1], body[2]));
                return Boolean.TRUE; //signup go good, return true
            } else {
                return Boolean.FALSE; //signup go bad, return false
            }
    } catch(Exception e) { }
        return null;
}

protected void onPostExecute(Boolean result) {
    //catching result from doInBackground
    listener.onSignupPerformed(result);
}

My question is, why when i first click on button, func return Boolean.TRUE but in SignupActivity signupValid variable is false (signup form not exit, but user is added to DB), but when i click signup button second time, ofc signup fail (because we make new user seconds ago) but signupValid change to true and Signup Form pass? I need to click SignupButton two times to finally exit form. Thanks for finding error in my code

EDIT:

I replaced .get() with Progress Dialog to block UI, but now i get Toast with not valid form even before AsyncTask for Signup do his job. And still, in first click signupValid is false even when from doInBackground() i get TRUE, on second click AsyncTask return FALSE but signupValid is changed to true

My UserDAO:

@Dao
public interface UserDao {
    @Query("SELECT * FROM users WHERE email = :email AND password = :password AND username = :username")
    User getUser(String username, String email, String password);
}

And ApplicationDatabase:

public abstract class ApplicationDatabase extends RoomDatabase {

public abstract UserDao userDao();

public static ApplicationDatabase getDatabase(final Context context){
    if(INSTANCE == null){
        synchronized (ApplicationDatabase.class){
            if(INSTANCE == null){
                INSTANCE = Room.databaseBuilder(context.getApplicationContext(), ApplicationDatabase.class, "database").build();
            }
        }
    }
    return INSTANCE;
}

private static volatile ApplicationDatabase INSTANCE;

Solution

If I understood the problem correctly - there is a race condition that makes the SignupActivity to fire the toast before the execution of Signup task is completed. Therefore:

signupButon.setOnClickListener(new View.OnClickListener(){
    @Override
    public void onClick(View v){
        if(validate()) {
            try {
                //new task every click
                Signup newSignup = new Signup(signup);
                //here start AsyncTask
                newSignup.execute(name, email, password).get();
            } catch (Exception e) {
                Toast.makeText(ERROR);
            }
        }
    }
});

While these lines:

 // if sign up succes, == true;
 if(signupValid) {
    Toast.makeText(SUCCES);
    finish();
 } else {
    Toast.makeText(ERROR);
 }

Should be a part of the listener (right now it seems that these lines are executed BEFORE the completion of your async task)

To clarify myself:

@Override
public void onSignupPerformed(Boolean result)
{ 
     if(result) {
        Toast.makeText(SUCCES);
        finish();
     } else {
        Toast.makeText(ERROR);
     }

}

Answered By - ymz