TextView on null reference error... Sqlite to listView. Android [duplicate]

This question already has an answer here:

• What is a Null Pointer Exception, and how do I fix it? 12 answers

I'm try to get data from a SQLite database into a listView. The application runs fine but when I open the New_Recipe activity I get a logcat error reading : `

java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference

It say that the error is in the productHolder.tx_items.setText(recipeGetterandSetter.getItems().toString()); line of the RecipeAdapter class.

Any solutions?

DatabaseHelper class:

public class DatabaseHelper extends SQLiteOpenHelper {
public static  final int DATABASE_VERSION = 4;
public static final String DATABASE_NAME = "Recipes.db";
public static final String CREATE_QUERRY = "create table " + RecipeContract.RecipeEntry.TABLE_NAME +"( NAME text, ITEMS text, STEPS text)";



public DatabaseHelper(Context context) {
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
    Log.d("Recipe Database", "Database should be made!");
}


@Override
public void onCreate(SQLiteDatabase db) {
    db.execSQL(CREATE_QUERRY);
    Log.d("Recipe Database", "Table should be made!");
}

public void addnameandsteps(SQLiteDatabase db,String name,String steps){

    ContentValues contentValues = new ContentValues();
    contentValues.put(RecipeContract.RecipeEntry.COL1,name);
    contentValues.put(RecipeContract.RecipeEntry.COL3, steps);
    db.insert(RecipeContract.RecipeEntry.TABLE_NAME, null, contentValues);
    Log.d("Recipe Database", "Name and steps data inserted!");


}

public void additems(SQLiteDatabase db,String items) {

    ContentValues contentValues = new ContentValues();
    contentValues.put(RecipeContract.RecipeEntry.COL2,items);
    db.insert(RecipeContract.RecipeEntry.TABLE_NAME, null, contentValues);
    Log.d("Recipe Database", "Item row inserted!");

}

public Cursor getItems(SQLiteDatabase db) {

    String[] projections = {RecipeContract.RecipeEntry.COL2};

    Cursor cursor = db.query(RecipeContract.RecipeEntry.TABLE_NAME,projections,
            null,null,null,null,null);

    return cursor;
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    db.execSQL("DROP TABLE IF EXISTS" + RecipeContract.RecipeEntry.TABLE_NAME);
    Log.d("Database", "Table exists");
    onCreate(db);

}
}

RecipeBackgroundTask class:

public class RecipeBackgroudTask extends AsyncTask<String,RecipeGetterandSetter,String> {
Context ctx;
RecipeAdapter recipeAdapter;
Activity activity;
ListView listView;
RecipeBackgroudTask(Context ctx)
{
    this.ctx = ctx;
    activity = (Activity)ctx;
}

@Override
protected void onPreExecute() {
    super.onPreExecute();
}

@Override
protected String doInBackground(String... params) {

    String method = params [0];

    DatabaseHelper databaseHelper = new DatabaseHelper(ctx);

    if (method.equals("add_name/steps"))
    {
        String name = params [1];
        String steps = params [2];

        SQLiteDatabase db = databaseHelper.getWritableDatabase();

        databaseHelper.addnameandsteps(db, name, steps);


    }
    if (method.equals("add_items"))
    {
        String items = params [1];

        SQLiteDatabase db = databaseHelper.getWritableDatabase();

        databaseHelper.additems(db, items);


    } else if(method.equals("get_items"))
    {
        listView = (ListView) activity.findViewById(R.id.listView);

        SQLiteDatabase db = databaseHelper.getReadableDatabase();
       Cursor cursor = databaseHelper.getItems(db);
        recipeAdapter = new RecipeAdapter(ctx,R.layout.display_recipe_row);
        String items;

        while (cursor.moveToNext())
        {
            items = cursor.getString(cursor.getColumnIndex(RecipeContract.RecipeEntry.COL2));
            RecipeGetterandSetter getterandSetter = new RecipeGetterandSetter(items);
            publishProgress(getterandSetter);
        }
            return "get_items";
    }


    return null;
}

@Override
protected void onProgressUpdate(RecipeGetterandSetter... values) {
    recipeAdapter.add(values[0]);

}

@Override
protected void onPostExecute(String result) {
    Toast.makeText(ctx,result,Toast.LENGTH_LONG).show();

    if (result.equals("get_items"))
    {
        listView.setAdapter(recipeAdapter);
    }
}
}

RecipeGetterandSetter class:

public class RecipeGetterandSetter {
private String items;

public RecipeGetterandSetter(String items)
{
    this.setItems(items);
}

public String getItems() {
    return items;
}

public void setItems(String items) {
    this.items = items;
}
}

RecipeAdapter class:

public class RecipeAdapter extends ArrayAdapter {

List list = new ArrayList();

public RecipeAdapter(Context context, int resource) {
    super(context, resource);
}


public void add(RecipeGetterandSetter object) {
    list.add(object);
    super.add(object);
}

@Override
public int getCount() {
    return list.size();
}

@Override
public Object getItem(int position) {
    return list.get(position);
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    View row = convertView;
    ProductHolder productHolder;
    if (row == null)
    {
        LayoutInflater layoutInflater = (LayoutInflater) this.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        row = layoutInflater.inflate(R.layout.activity_new__recipe,parent,false);
        productHolder = new ProductHolder();
        productHolder.tx_items = (TextView) row.findViewById(R.id.tx_items);
        row.setTag(productHolder);

    } else {

        productHolder = (ProductHolder) row.getTag();
    }
    RecipeGetterandSetter recipeGetterandSetter = (RecipeGetterandSetter)getItem(position);
    productHolder.tx_items.setText(recipeGetterandSetter.getItems().toString());


    return row;
}

static class ProductHolder
{
    TextView tx_items;
}
}

I'm not sure if this has anything to do with the error but display_recipe_row layout:

<RelativeLayout xmlns:android="http://ift.tt/nIICcg"
    android:layout_width="match_parent" android:layout_height="75dp"
    android:background="#2787A4">

<TextView
    android:layout_width="70dp"
    android:layout_height="match_parent"
    android:id="@+id/tx_items"
    android:layout_alignParentLeft="true"
    android:text="12A"
    android:gravity="center"
    android:textAppearance="?android:textAppearanceLarge"/>