Question

I’m pretty new to Android and I need some guidance.

I have two activities so far. The first one contains an ActionBar and a ListView. I want the ListView to be populated with rows containing a TextView and a CheckBox. The text is represented by an username read from a database.The ActionBar has buttons for actions: “new” and “delete”. “new” opens a new activity which adds a new user into the database, delete action should delete checked entries from the list and database. Screens:

Main activity: https://i.stack.imgur.com/S3y0r.jpg

Create profile activity: https://i.stack.imgur.com/IyKYA.jpg

To get these I used SQLiteHelper and a datasource for the database and a custom ArrayAdapter for the ListView. I have one problem and some concerns, listed below.

1 . The problem: when I add a new user, I can only see the changes in the ListView after I exit the app using the back button.

2 . Is a custom ArrayAdapter a good solution for this or should I use a CursorAdapter? When clicked, the list item should use the information associated with it into another activity/fragment. Below is my custom adapter. It works right now, but the next step is to implement the delete action, and i’m not entirely sure how I do that. This is where i need advice. Thank you!

    public class CustomUserAdapter extends ArrayAdapter<UserProfile>{

        ArrayList<UserProfile> users;
        private LayoutInflater inflater;

        public CustomUserAdapter(Context context, ArrayList<UserProfile> users) {
        // TODO Auto-generated constructor stub
        super(context, R.layout.users_list_row, users);
        this.users = users;
        inflater = LayoutInflater.from(context);
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
        UserProfile user = users.get(position);
        CheckBox checkBox;
        TextView textView;

        if(convertView == null){
            convertView =  inflater.inflate(R.layout.users_list_row, null);
            checkBox = (CheckBox) convertView.findViewById(R.id.checkElement);
            textView = (TextView) convertView.findViewById(R.id.textElement);

            //tag row
            convertView.setTag(new UserHolder(textView, checkBox));
        } else {
            UserHolder userHolder = (UserHolder) convertView.getTag();
            checkBox = userHolder.getCheckBox();
            textView = userHolder.getUserText();
        }

        //tag checkbox
        checkBox.setTag(user);

        //checkbox listener
        checkBox.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
            }
        });

        checkBox.setChecked(false);
        textView.setText(user.getUsername());

        return convertView;
            }
      }

Answer 1

1) after changing your arraylist, remember to call “adapter.notifyDataSetChanged();” on your adapter which is linked with your list view

2) an arrayadapter should work just fine. remember when you delete a contact from your arraylist, to call notfiydatasetchanged again on your adapter. Also keep in mind in order to delete an Sql entry of your objects, you will need an id or some sort of ID that you can reference to your SQLite database (id, auto increment is standard)

here is an example for implementing listener on each item and deleting, using a dialog.

list.setOnItemClickListener(new OnItemClickListener() {

        public void onItemClick(AdapterView<?> arg0, View arg1, final int arg2, long arg3) {
            // TODO Auto-generated method stub
            AlertDialog.Builder dialog = new AlertDialog.Builder(ContactExampleActivity.this);
            dialog.setTitle("title");
            dialog.setMessage("message");
            dialog.setPositiveButton("delete", new DialogInterface.OnClickListener(){
                public void onClick(DialogInterface dialog, int which) {
                    //delete from array and delete from sqlite database here

                    adapter.notifyDataSetChanged();
                }
            });