SQLite Database makes Android App close without error

Question

I'm trying to create a database to store Sudokus for a Sudoku app. I save them as strings which I wanna split into an ArrayList later on. I created a really simple activity to test this out, which consists of a GridView that shows the Sudoku with an adapter. The GridView works just fine when I try to insert something I don't get from the DB, but when I try to use the DB the app crashes right when it opens. I followed various tutorials about SQLite DB and even tried some of my teacher code but I really don't know what's happening here.

Here's my main activity code:

import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.GridView;
import android.widget.TextView;
import android.widget.Toast;

import java.util.ArrayList;

import static android.content.ContentValues.TAG;
import static biel.edu.fje.bdsudokuprova.SudokuDB.nomTaulaSudokus;

public class MainActivity extends AppCompatActivity {

    static final String[] numbers = new String[] {
            "1", "2", "3", "4", "5", "6", "7", "8", "9",
            "1", "2", "3", "4", "5", "6", "7", "8", "9",
            "1", "2", "3", "4", "5", "6", "7", "8", "9",
            "1", "2", "3", "4", "5", "6", "7", "8", "9",
            "1", "2", "3", "4", "5", "6", "7", "8", "9",
            "1", "2", "3", "4", "5", "6", "7", "8", "9",
            "1", "2", "3", "4", "5", "6", "7", "8", "9",
            "1", "2", "3", "4", "5", "6", "7", "8", "9",
            "1", "2", "3", "4", "5", "6", "7", "8", "9"};

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

        SudokuDB sudoDButil = new SudokuDB(getBaseContext());
        SQLiteDatabase db = sudoDButil.getWritableDatabase(); // This is where it fails (I have to
                                                              // comment from here to line 60 for the app to at least open)

        ContentValues valors = new ContentValues();
        valors.put(nomTaulaSudokus, "123456789123456789123456789123456789123456789123456789123456789123456789123456789");
        db.insert(nomTaulaSudokus, null, valors);
        Cursor cursorSudoku = db.rawQuery("select sudoku from sudokus", null);
        String sudo = null;

        try {
            if (cursorSudoku.moveToFirst()) {
                do {
                    sudo = cursorSudoku.getString(1);
                } while(cursorSudoku.moveToNext());
            }
        } catch (Exception e) {
            Log.d(TAG, "Error a l'hora d'intentar agafar la informació de la base de dades");
        } finally {
            if (cursorSudoku != null && !cursorSudoku.isClosed()) {
                cursorSudoku.close();
            }
        }

        ArrayList<String> sudoArray = new ArrayList<String>();
        for (int i = 0; i < 81; i++) {
            sudoArray.add("1");
            //String.valueOf(sudo.charAt(i))
        }

        GridView gridView = findViewById(R.id.gridView);

        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
                android.R.layout.simple_list_item_1, numbers);

        gridView.setAdapter(adapter);

        gridView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            public void onItemClick(AdapterView<?> parent, View v,
                                    int position, long id) {
                Toast.makeText(getApplicationContext(),
                        ((TextView) v).getText(), Toast.LENGTH_SHORT).show();
            }
        });
    }
}

Edit: I forgot to mention that I use the "numbers" variable to test out if the GridView works fine without using the ArrayList. Sorry, it's a bit messy.

And here's my DB helper class:

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class SudokuDB extends SQLiteOpenHelper {

    public static final String nomBd = "Sudoku";
    public static final int versioBd = 1;
    public static final String nomTaulaSudokus = "sudokus";
    public static final String columnIdSudokus = "id";
    public static final String columnSudo = "sudoku";

    private static final String SQL_CREACIO_TAULA_SUDOKUS = "CREATE TABLE " + nomTaulaSudokus + " ( "
            + columnIdSudokus + "INTEGER PRIMARY KEY AUTOINCREMENT,"
            + columnSudo + " TEXT )";

    private static final String SQL_ESBORRAT_TAULA_SUDOKUS = "DROP TABLE IF EXISTS "
            + nomTaulaSudokus;

    public SudokuDB(Context context) {
        super(context, nomBd, null, versioBd);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(SQL_CREACIO_TAULA_SUDOKUS);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL(SQL_ESBORRAT_TAULA_SUDOKUS);
        onCreate(db);
    }

    @Override
    public void onDowngrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        onUpgrade(db, oldVersion, newVersion);
    }
}

Thank you very much for any help given and sorry if this is any nuisance for you all. It might be a really simple and silly error but I still don't understand very well how SQLite DB works.