Question

I’ve been working on this application but have come across a problem that I have been unable to figure out. I have a listview that is populated with the contents from an adapter, and each row has their specific information (Uniform). The problem comes when I try to retrieve the value of a checkbox that is found in that particular row.

The code in question is below:

I build an AlertDialog object so I can get my information from the user. My layout code consists of a LinearLayout in horizontal orientation with 3 elements an image, text, check box. I build my AlertDialog with R.layout.listview_layout, which is a custom layout that I made.

One thing I tried to do is get the CheckBox View from the adapter, however; when I look at it via cb.isChecked(), no matter what row i’m on its always unchecked (aka false). In order to debug this further I took the same adapter and retrieved the text via the same methodology and it returned specific information about that row, as it should.

Any ideas how I can handle this?

Simply Put:

I would just like to get the value of the CheckBox at each given row


c = help.returnContacts();

    AlertDialog.Builder ab = new AlertDialog.Builder(this);
    ab.setTitle("Select contacts");

    final SimpleCursorAdapter adapter = new SimpleCursorAdapter(
            getApplicationContext(), R.layout.listview_layout, c,
            new String[] { ClientOpenDbHelperUtility.COL_NAME,
                    ClientOpenDbHelperUtility.COL_SEL }, new int[] {
                    R.id.txt_name, R.id.cb_select });
    ab.setAdapter(adapter, null);

    ab.setPositiveButton("Confirm", new Dialog.OnClickListener() {

        @Override
        public void onClick(DialogInterface dialog, int which) {

            Cursor c = adapter.getCursor();
            for (int i = 0; i < adapter.getCount(); i++) {

                CheckBox cb = (CheckBox) adapter.getView(i, null, null)
                        .findViewById(R.id.cb_select);
                TextView t = (TextView) adapter.getView(i, null, null)
                        .findViewById(R.id.txt_name);

                Log.d("DEBUG", "Checked = " + cb.isChecked());
                Log.d("DEBUG", "Message = " + t.getText().toString());
                if (cb.isChecked()) {

                    help
                            .updateSelection(
                                    c
                                            .getColumnIndex(ClientOpenDbHelperUtility.COL_UID),
                                    true);
                } else {
                    help
                            .updateSelection(
                                    c
                                            .getColumnIndex(ClientOpenDbHelperUtility.COL_UID),
                                    false);
                }

            }
            c.close();
            help.closeAll();

        }

    });
    ab.show();

}

Thanks for reading!

Answer 1

You shouldn’t call getView directly. Doing so generates a fresh view (or recycles and overwrites an old one) based on the contents of your database.

Also, once your rows scroll off the top or bottom of the screen they will be recycled for use in new rows that appear. All of your data but the currently visible rows are most likely to have already vanished by the time your onClick method gets called.

You have two options:

1. Persist changes immediately to the database – set an OnClickListener on your checkbox or on the row and update your database on each click event.

2. Save changes to an instance variable and then apply later – define a Map<Integer, Boolean> changes instance variable for your activity and call changes.put(position, isChecked) whenever there is a click. Then when your user clicks “Apply” or whatever your onClick is, go through changes and persist each one to the database. It’s basically the same as what you have now except you would be using a stable object to store the unsaved changes.