通过微调框（C＃）过滤后，在Listview上维护选中的itens

Question

I'm running into a problem that I cannot fix, I created an custom dialog that shows a Listview filled with my objects by an custom BaseAdapter, I open this dialog when I click into an EditText, so I can check the itens that I want, and all this itens will be passed back to the EditText, see the image below:

When I click the OK button, my EditText will be filled with (Item A, Item B) And if I click again on the EditText, Item A and Item B should be already checked... I managed to do this, but now, I need to filter the Listview with the current category, to do this, I added an ItemSelect listener on my spinner that will query the database to get the filtered itens, cleared my current list, added the new list and called NotifyDataSetChanged() on the adapter, this works just fine.

The problem is that I need to keep track of the selected itens even if I change the categories, for instance, I checked 2 itens in the "Category one", changed to "Category two" and checked 2 more itens, at the end, I need to get all these 4 itens, and for example, Item A is present in more then one category, how do I keep it checked when I change between the categories?

For now, this is my codes:

class MultipleAnimalSelectionAdapter : BaseAdapter<AnimalBean>
{
    private List<AnimalBean> animaisList;
    private Context cx;
    private Dictionary<int, bool> checkedAnimals = new Dictionary<int, bool>();

    public MultipleAnimalSelectionAdapter(Context cx, List<AnimalBean> animaisList)
    {
        this.cx = cx;
        this.animaisList = animaisList;
        for (int i = 0; i < animaisList.Count; i++)
        {
            checkedAnimals.Add(i, false);
        }
    }

    public override AnimalBean this[int position]
    {
        get
        {
            return animaisList[position];
        }
    }

    public override int Count
    {
        get
        {
            return animaisList.Count;
        }
    }

    public override long GetItemId(int position)
    {
        return position;
    }


    public override View GetView(int position, View convertView, ViewGroup parent)
    {
        View row = convertView;
        ViewHolder viewHolder;

        if (row == null)
        {
            row = LayoutInflater.From(cx).Inflate(Resource.Layout.dialog_animais_row, null, false);
            viewHolder = new ViewHolder();
            viewHolder.CbAnimal = row.FindViewById<CheckBox>(Resource.Id.cbAnimal);

            row.Tag = viewHolder;
        }
        else
        {
            viewHolder = (ViewHolder)row.Tag;
        }

        AnimalBean animal = (AnimalBean) GetItem(position);

        viewHolder.CbAnimal.Clickable = false;
        viewHolder.CbAnimal.Focusable = false;
        viewHolder.CbAnimal.Text = animal.AnimalNome;
        viewHolder.CbAnimal.Tag = position;

        if (checkedAnimals[(int)viewHolder.CbAnimal.Tag])
            viewHolder.CbAnimal.Checked = true;
        else
            viewHolder.CbAnimal.Checked = false;
        return row;
    }

    public void ToogleChecked(int position)
    {
        if (checkedAnimals[position])
            checkedAnimals[position] = false;
        else
            checkedAnimals[position] = true;

        NotifyDataSetChanged();
    }

    public void ToogleChecked(AnimalBean animal)
    {
        for(int i = 0; i < animaisList.Count; i++)
        {
            if (animaisList[i].AnimalId == animal.AnimalId)
                ToogleChecked(i);
        }

        NotifyDataSetChanged();
    }

    public List<int> GetCheckedAnimaisPosition()
    {
        List<int> checkedPos = new List<int>();
        for(int i = 0; i < checkedAnimals.Count; i++)
        {
            if(checkedAnimals[i])
            {
                checkedPos.Add(i);
            }
        }
        return checkedPos;
    }

    public List<AnimalBean> GetCheckedAnimais()
    {
        List<AnimalBean> animais = new List<AnimalBean>();

        for(int i = 0; i < checkedAnimals.Count; i++)
        {
            if (checkedAnimals[i])
                animais.Add(animaisList[i]);
        }

        return animais;
    }

    // ViewHolder class
    private class ViewHolder : Java.Lang.Object
    {
        public CheckBox CbAnimal;
    }

}

I needed to keep track of the checkbox position, so I could maintain it status when I scroll the ListView, otherwise it would act strange checking random itens...

Then I create the ListView this way:

        ListView lvDialogAnimais = dialog.FindViewById<ListView>(Resource.Id.lvDialogAnimais);
        MultipleAnimalSelectionAdapter animaisAdapter = new MultipleAnimalSelectionAdapter(this, animaisList);
        lvDialogAnimais.Adapter = animaisAdapter;

        foreach (AnimalBean selAnimal in selectedAnimais)
        {
            animaisAdapter.ToogleChecked(selAnimal);
        }

        lvDialogAnimais.ItemClick += (ss, ee) =>
        {
            animaisAdapter.ToogleChecked(ee.Position);
            selectedAnimais.Clear();
            selectedAnimais.AddRange(animaisAdapter.GetCheckedAnimais());
        };

I use the ToogleChecked() so I keep the checked itens when I reopen the dialog...

And when I click the OK button on my dialog, I simple use a Join function:

Button btnCDOk = dialog.FindViewById<Button>(Resource.Id.btnCDOk);
        btnCDOk.Click += (ss, ee) =>
        {
            tmp.Text = string.Join(", ", selectedAnimais);
            dialog.Dismiss();
        };

To filter the ListView, I do this:

spinDialogCategorias.ItemSelected += (ss, ee) =>
        {
            animaisList.Clear();

            // Query the database

            animaisAdapter.NotifyDataSetChanged(); }

This works just perfect, the way I want, but I need to be able to filter this ListView and always maintain the checked itens ragardless of changes in the data list...

Any help will be appreciated! Thank you very much!

Answer 1

也许您可以只建立一个临时列表，在其中跟踪这对夫妇，然后可以迭代该列表，以构建一个元素数组以传递给您的适配器（或者您可以将该列表传递给新的适配器），之后调用NotifyDataSetChanged（）重绘listView