Cursor query returning 0

Question

I am building an application with database but a problem arises when I am retrieving the values from the database it returns empty (i.e. returned cursor has 0 tuples) and I am sure that database contains some information into it. I am providing my code please help if you noticed any error.

Fragment where user inputs data to database:

    public class FCar extends Fragment implements AdapterView.OnItemSelectedListener {

    public FCar() {
    }

    CarDataBaseAdapter carDataBaseAdapter;
    SessionManagement session;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

//        inflating the view
        final View rootView = inflater.inflate(R.layout.fragment_car, container, false);
//        declaring stuff, not sure why it has to be final
        final Spinner carSpinner;
        final EditText editTextDistance, editTextMin;
        Button btnSubmitCar;

//      create new car database
        carDataBaseAdapter = new CarDataBaseAdapter(getActivity());
        carDataBaseAdapter = carDataBaseAdapter.open();
        SQLiteDatabase x = carDataBaseAdapter.getDatabaseInstance();

        session = new SessionManagement(getActivity().getApplicationContext());

//        display existing tables
/*
        Cursor hi = x.rawQuery("SELECT name FROM sqlite_master WHERE type='table'", null);
        hi.moveToFirst();
        int f = hi.getCount();
        String g = Integer.toString(f);
        Toast.makeText(getActivity().getApplicationContext(), g, Toast.LENGTH_LONG).show();
        while ( !hi.isAfterLast() ) {
            String h = (hi.getString( hi.getColumnIndex("name")) );
            hi.moveToNext();
            Toast.makeText(getActivity().getApplicationContext(), h, Toast.LENGTH_LONG).show();
        }
*/

        // Get References of Views
        carSpinner = (Spinner) rootView.findViewById(R.id.spinner_car_type);
        editTextDistance = (EditText) rootView.findViewById(R.id.editTextcarDistance);
        editTextMin = (EditText) rootView.findViewById(R.id.editTextcarMin);

        // Spinner click listener
        carSpinner.setOnItemSelectedListener(this);

//        set default spinner selection
        carSpinner.setSelection(0);

        // Spinner Drop down elements
        List<String> categories = new ArrayList<>();
        categories.add("Standard");
        categories.add("Truck");
        categories.add("Electric/Hybrid");

        // Creating adapter for spinner
        ArrayAdapter<String> dataAdapter = new ArrayAdapter<>(getActivity(), android.R.layout.simple_spinner_item, categories);

        // Drop down layout style - list view with radio button
        dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

        // attaching data adapter to spinner
        carSpinner.setAdapter(dataAdapter);

//      identifying the button
        btnSubmitCar = (Button) rootView.findViewById(R.id.button_car_submit);
        btnSubmitCar.setOnClickListener(new View.OnClickListener() {

                                            public void onClick(View v) {

//              take username entry from login / sign up form via method in FProfile
//                String currentUser = getSingleEntry();
                                                String username = session.getUsername();

                                                SimpleDateFormat formata = new SimpleDateFormat("MM/dd/yyyy", Locale.CANADA);
                                                String date = formata.format(new Date());

                                                String type = carSpinner.getSelectedItem().toString();

//                convert distance to integer
                                                int distance = 0;
                                                try {
                                                    distance = Integer.parseInt(editTextDistance.getText().toString());
                                                } catch (NumberFormatException nfe) {
                                                    System.out.println("Could not parse distance " + nfe);
                                                }
//                convert minutes to integer
                                                int time = 0;
                                                try {
                                                    time = Integer.parseInt(editTextMin.getText().toString());
                                                } catch (NumberFormatException nfe) {
                                                    System.out.println("Could not parse minutes" + nfe);
                                                }

                                                // Save the Data in Database
                                                carDataBaseAdapter.insertEntry(username, date, type, distance, time);
//                                              link back to input menu
                                                Intent intent = new Intent(getActivity(), MainActivity.class);

                                                intent.putExtra("caller", "Input");
                                                startActivity(intent);

                                            }
                                        }
        );
        return rootView;
    }

This is my query:

public Cursor getCarEntry(String username, String Day, String Type) {

    Cursor carCursor = db.query(true, "CAR", new String[]{"distance, time"}, "USERNAME=? AND DATE=? AND TYPE=?", new String[]{username, Day, Type}, null, null, null, "50");
    if (carCursor.getCount() < 1) {
        carCursor.close();
    }
        carCursor.moveToFirst();
        for (int i = 0; i < carCursor.getCount(); i++) {
            int distance = carCursor.getInt(carCursor.getColumnIndex("DISTANCE"));
            int time = carCursor.getInt(carCursor.getColumnIndex("TIME"));
        }
        return carCursor;

Then I retrieve it in a fragment

            carStandardCursors[i] = carDataBaseAdapter.getCarEntry(currentUsername, searchDate, "Standard");

Then I made a loop to perform math on the cursors

        for (int i = 0; i < 7; i++) {
        Cursor ccursor = carStandardCursors[i];
        carStandardTotal = CalculateCarStandard(ccursor);
        carStandard[dex] = carStandardTotal;

And I found that the values in carStandardCursors[i] were all zero.

score 0 · Answer 1 · answered Apr 24 '17 at 06:59

0

Use Facebook Stetho Library to check whether the database contains Values or not.Then only you can get an idea.

stetho library

answered Apr 24 '17 at 06:59

Rajesh.k

2,327
1
16
19

I used a DatabaseManager to view my database, and there is data in there. – Sam Apr 24 '17 at 23:33
Run with a breakpoint immediately after the query. You can then get the actual value of the interpreted query (the query string) which you can cut and paste into the DB manager. – MikeT Apr 25 '17 at 06:40

Akash Dubey · Answer 2 · 2017-04-25T06:16:47.883

the problem is here,

    public Cursor getCarEntry(String username, String Day, String Type) {

Cursor carCursor = db.query(true, "CAR", **new String[]{"distance, time"}**, "USERNAME=? AND DATE=? AND TYPE=?", new String[]{username, Day, Type}, null, null, null, "50");
if (carCursor.getCount() < 1) {
    carCursor.close();
}
    carCursor.moveToFirst();
    for (int i = 0; i < carCursor.getCount(); i++) {
        int distance = carCursor.getInt(carCursor.getColumnIndex("DISTANCE"));
        int time = carCursor.getInt(carCursor.getColumnIndex("TIME"));
    }
    return carCursor;

change it to

   public Cursor getCarEntry(String username, String Day, String Type) {

Cursor carCursor = db.query(true, "CAR", new String[]{"DISTANCE", "TIME"}, "USERNAME=? AND DATE=? AND TYPE=?", new String[]{username, Day, Type}, null, null, null, "50");
if (carCursor.getCount() < 1) {
    return carCursor;
}else{
     if (carCursor!= null) {
        carCursor.moveToNext();
    }

    return carCursor;
}

and then get this cursor at your method call and then at their

   Cursor call = classObject.getCarEntry(username, Day, Type);

   int distance = call .getInt(carCursor.getColumnIndex("DISTANCE"));
   int time = call .getInt(carCursor.getColumnIndex("TIME"));

if more than one data then use while loop and ArrayAdapter

Hmm, that doesn't seem to be the problem, its still giving me the exact same thing. Thanks for the reply though! — Sam, Apr 24 '17 at 14:49

Cursor query returning 0

2 Answers2