How to dynamically update the listview when you add and delete item in the database?

Question

I know there's a lot of suggestion here in SO to update the listview, I've tried them but nothing works. Can you please help me? I don't know if I missed something. Here is my code:

simpleAdapterConsumerList= new ConsumerList(RegistrationActivity.this, arraylistRegisteredConsumer, R.layout.registeredconsumerlistattributecell, Constants.REGISTERED_ATTRIBUTE_KEYS, Constants.REGISTERED_ATTRIBUTES_VIEWS, false);
        lv_ConsumersList.setAdapter(simpleAdapterConsumerList);
        registeredConsumerCount = lv_ConsumersList.getCount();

When I tick the submit button i want to automatically update the lisview without leaving the page. And when I clicked listview an alert dialog will appear asking if the user wants to delete the selected item, if the user clicked the OK button it was already deleted in my database but the listview is not updated. I still need to leave the page to see the updated listview.I tried to put codes below but nothing works. ()

simpleAdapterConsumerList.notifyDataSetChanged();

and

((BaseAdapter) lv_ConsumersList.getAdapter()).notifyDataSetChanged();

here id my code that add new data in the database

btn_Register.setOnClickListener(new OnClickListener() 
    {
        @Override
        public void onClick(View v) 
        {
            Emp = txt_Emp.getText().toString();
            Lastname = txt_Lname.getText().toString();
            Firstname = txt_Fname.getText().toString();
            Middlename = txt_Mname.getText().toString();
            Cp = txt_Cp.getText().toString();
            Email = txt_Email.getText().toString();
            fullName = Lastname +" "+ Firstname +" "+Middlename;
            careFriend = sharedPreferences.getString(Constants.SHARED_PREFERENCES_CAREFRIEND, "");  
            companyName = sharedPreferences.getString(Constants.SHARED_PREFERENCES_COMPANY_CARE_FRIEND, "");
            consumercompanycode =  sharedPreferences.getString(Constants.SHARED_PREFERENCES_COMPANYCODE_CARE_FRIEND, "");
            SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy HH:mm");
            emailmark = "Not send";
            consumerId = sharedPreferences.getInt(Constants.SHARED_PREFERENCES_CONSUMER_ID, 1);
            consumerId = consumerId + 1;
            if (!Lastname.equals(""))
            {
                ....
{
                            String currentDateandTime = sdf.format(new Date());
                            databaseAdapter.SaveConsumerDetails(new Constructor(Emp, Lastname, Firstname, Middlename, Cp, Email, fullName, careFriend, companyName, emailmark, currentDateandTime, consumerId, consumercompanycode));
                            sharedPreferencesEditor.putInt(Constants.SHARED_PREFERENCES_CONSUMER_ID, consumerId);
                            sharedPreferencesEditor.commit();
                            simpleAdapterConsumerList.notifyDataSetChanged();
                            //((BaseAdapter) lv_ConsumersList.getAdapter()).notifyDataSetChanged(); 
                            //registeredConsumerCount = lv_ConsumersList.getCount();
                            Toast.makeText(RegistrationActivity.this, "Registered successfully. " + currentDateandTime, Toast.LENGTH_LONG).show();                                                                          simpleAdapterConsumerList.notifyDataSetChanged();
                            Clear();

                        }else{
          ....          
        }

on my delete button. here is my code

public void onClick(DialogInterface dialog, int id) 
                {
                    databaseAdapter.deleteSelectedItem(ID);
                    Toast.makeText(RegistrationActivity.this, "Delete " + ID, Toast.LENGTH_LONG).show();                                                                            
                    simpleAdapterConsumerList.notifyDataSetChanged();
                }

....
final Cursor cursorRegisteredConsumer = databaseAdapter.getCursorRegisteredConsumer();

   ....
//on my databaseAdapter here is my code

public Cursor getCursorRegisteredConsumer(){
    Cursor c = dbSqlite.query(Constants.DATABASE_TABLE_CONSUMER, new String[] { Constants.DATABASE_COLUMN_ID, Constants.CONSUMER_EMPNO, Constants.CONSUMER_FIRSTNAME, Constants.CONSUMER_LASTNAME, Constants.CONSUMER_MIDDLEINITIAL, Constants.CONSUMER_CELLPHONENO, Constants.CONSUMER_EMAIL, Constants.CONSUMER_FULLNAME, Constants.CONSUMER_CAREFRIEND, Constants.CONSUMER_COMPANY, Constants.CONSUMER_REGISTRATIONDATE, Constants.CONSUMER_EMAILMARK,Constants.CONSUMER_ID,Constants.CONSUMER_COMPANYCODE}, null , null, null, null, Constants.DATABASE_COLUMN_ID + " ASC");
    //c.setNotificationUri(getContext().getContentResolver(), uri);
    if (c != null) {
        c.moveToFirst();
    }
    return c;

}

Karakuri Karakuri · Accepted Answer · 2013-06-05T02:11:43

There are two parts to this:

1. The Cursor that backs your adapter doesn't change by itself.

The Cursor that backs your adapter points to a set results from a query. When the data in the database changes, the Cursor still points to the same result set. You need to query again to get updated data. You can do this yourself whenever you manually delete an item.

If you've set up a proper ContentProvider for your database, you could instead use a ContentObserver and/or a CursorLoader (which sets up a ContentObserver itself) and just make sure that in your ContentProvider's query(...) method you do this:

Cursor cursor = ...; // query
cursor.setNotificationUri(getContext().getContentResolver(), uri);
return cursor;

2. If you get a new Cursor, you need to replace the old one.

You may have a new cursor, but your adapter still uses the old one, so you need to replace them. Add this method to your adapter and call it whenever you get the result of a query.

public void swapCursor(Cursor newCursor) {
    if (cursor != null && oldCursor.isOpen()) {
        cursor.close();
    }
    cursor = newCursor;
    notifyDataSetChanged();
}

How to dynamically update the listview when you add and delete item in the database?

4 Answers