How To Use Or Instantiate Sqlite Database Helper Class Instance Inside A Custom Dapter Class In Android?

I am absolute beginner to Android. Now I am creating a tutorial project. In my project I am using ListView with custom adapter. But I created the custom adapter as a different and

Solution 1:

Does not look like a big problem, instantiate it in your constructor:

public TaskListAdapter(Context context,ArrayList<Task> values)
{
    super(context,-1,values);
    this.dbHelper = new DatabaseHelper(context.getApplicationContext());
    this.context = context;
    this.values = values;
}

Then use it in your OnClickListener:

Button doneBtn = (Button)rowView.findViewById(R.id.task_row_done_btn);
doneBtn.setTag(values.get(position).getId());
doneBtn.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        dbHelper.markAsDone(v.getTag());
    }
});

Don't forget to close your Database in DatabaseHelper.markAsDone

Solution 2:

Firstly if you want to use the db inside the adapter , you can use CursorAdapter not ArrayAdapter ,

if you want to stay on arrayAdapter , then you can pass th db Object in the construcor

Solution 3:

You should make the DatabaseHelper class as thread-safe Singleton and then get that instance from the adapter.

public class DatabaseHelper extends SQLiteOpenHelper{
     private static DatabaseHelper dbHelper;

    public static DatabaseHelper getInstance() {
        if(dbHelper == null)
        {
            synchronized (DatabaseHelper.class)
            {
                if(dbHelper == null)
                {
                    dbHelper = new DatabaseHelper(MyApplicationInstance.getAppContext());
                }
            }
        }

        return dbHelper;
    }

    private DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }
}

And then in the CustomAdapter just execute your commands as DatabaseHelper.getInstance().insert()

Hope this helps.