Custom Filtering ArrayAdapter in ListView

Question

I am a begginer in Android but I tried to make a custom listview filtering and I it worked somehow. The only problem I have is that the ArrayList that I kept all the values ( "original" ArrayList ) , is getting lower and lower on items in every filtering. I can't explain this but I thought that you can help me somehow .

Anyway here is the Custom ArrayAdaptor :

public class PkmnAdapter extends ArrayAdapter<Pkmn> {

private ArrayList<Pkmn> original;
private ArrayList<Pkmn> fitems;
private Filter filter;

public PkmnAdapter(Context context, int textViewResourceId, ArrayList<Pkmn> items) {
        super(context, textViewResourceId, items);
        this.original = items;//new ArrayList<Pkmn>();
        this.fitems = items;//new ArrayList<Pkmn>();
}

@Override
public void add(Pkmn item){
    original.add(item);
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
        View v = convertView;
        if (v == null) {
            LayoutInflater vi = (LayoutInflater)getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            v = vi.inflate(R.layout.row, null);
        }
        Pkmn pkmn = original.get(position);
        if (pkmn != null) {
                TextView tt = (TextView) v.findViewById(R.id.RlabPName);
                TextView dex = (TextView)v.findViewById(R.id.RlabDex);
                ImageView img = (ImageView)v.findViewById(R.id.RimgPkmn);

                if (tt != null) { tt.setText(pkmn.getName()); }
                if (dex != null){ dex.setText(CalcDex(pkmn.getId())); }
                if (img != null){
                    int resId = getContext().getResources().getIdentifier("dex" + pkmn.getId(), "drawable", "com.compileguy.pokebwteam");
                    img.setImageResource(resId);
                }
        }
        return v;
}

@Override
public Filter getFilter()
{
    if (filter == null)
        filter = new PkmnNameFilter();

    return filter;
}

private class PkmnNameFilter extends Filter
{
        @Override
        protected FilterResults performFiltering(CharSequence constraint)
        {   
            FilterResults results = new FilterResults();
            String prefix = constraint.toString().toLowerCase();

            if (prefix == null || prefix.length() == 0)
            {
                ArrayList<Pkmn> list = new ArrayList<Pkmn>(original);
                results.values = list;
                results.count = list.size();
            }
            else
            {
                final ArrayList<Pkmn> list = original;

                int count = list.size();
                final ArrayList<Pkmn> nlist = new ArrayList<Pkmn>(count);

                for (int i=0; i<count; i++)
                {
                    final Pkmn pkmn = list.get(i);
                    final String value = pkmn.getName().toLowerCase();

                    if (value.startsWith(prefix))
                    {
                        nlist.add(pkmn);
                    }
                }
                results.values = nlist;
                results.count = nlist.size();
            }
            return results;
        }

        @SuppressWarnings("unchecked")
        @Override
        protected void publishResults(CharSequence constraint, FilterResults results) {
            fitems = (ArrayList<Pkmn>)results.values;
            clear();
            int count = fitems.size();
            for (int i=0; i<count; i++)
            {
                Pkmn pkmn = (Pkmn)fitems.get(i);
                add(pkmn);
            }

            if (fitems.size() > 0)
                notifyDataSetChanged();
            else
                notifyDataSetInvalidated();
        }

    }


private String CalcDex(int id){
    String s = String.valueOf(id);
    if (s.length() == 1)
        s = "00"+s;
    else if (s.length() == 2)
        s = "0"+s;
    return '#'+s;
}

}

NOTE: The listview is showing correctly the items but when for exaple I remove a letter in the editbox ( which triggers the filtering ) this is where the problems start.

--- EDIT ---

@Janusz: Many thanks for your answer . That solved my problem .

Here is the source code that works for me , so if anyone has the same issue they could try this one :

private ArrayList<Pkmn> original;
private ArrayList<Pkmn> fitems;
private Filter filter;

public PkmnAdapter(Context context, int textViewResourceId, ArrayList<Pkmn> items) {
        super(context, textViewResourceId, items);
        this.original = new ArrayList<Pkmn>(items);
        this.fitems = new ArrayList<Pkmn>(items);
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
        View v = convertView;
        if (v == null) {
            LayoutInflater vi = (LayoutInflater)getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            v = vi.inflate(R.layout.row, null);
        }
        Pkmn pkmn = fitems.get(position);
        if (pkmn != null) {
                TextView tt = (TextView) v.findViewById(R.id.RlabPName);
                TextView dex = (TextView)v.findViewById(R.id.RlabDex);
                ImageView img = (ImageView)v.findViewById(R.id.RimgPkmn);

                if (tt != null) { tt.setText(pkmn.getName()); }
                if (dex != null){ dex.setText(CalcDex(pkmn.getId())); }
                if (img != null){
                    int resId = getContext().getResources().getIdentifier("dex" + pkmn.getId(), "drawable", "com.compileguy.pokebwteam");
                    img.setImageResource(resId);
                }
        }
        return v;
}

@Override
public Filter getFilter()
{
    if (filter == null)
        filter = new PkmnNameFilter();

    return filter;
}

private class PkmnNameFilter extends Filter
{
        @Override
        protected FilterResults performFiltering(CharSequence constraint)
        {   
            FilterResults results = new FilterResults();
            String prefix = constraint.toString().toLowerCase();

            if (prefix == null || prefix.length() == 0)
            {
                ArrayList<Pkmn> list = new ArrayList<Pkmn>(original);
                results.values = list;
                results.count = list.size();
            }
            else
            {
                final ArrayList<Pkmn> list = new ArrayList<Pkmn>(original);
                final ArrayList<Pkmn> nlist = new ArrayList<Pkmn>();
                int count = list.size();

                for (int i=0; i<count; i++)
                {
                    final Pkmn pkmn = list.get(i);
                    final String value = pkmn.getName().toLowerCase();

                    if (value.startsWith(prefix))
                    {
                        nlist.add(pkmn);
                    }
                }
                results.values = nlist;
                results.count = nlist.size();
            }
            return results;
        }

        @SuppressWarnings("unchecked")
        @Override
        protected void publishResults(CharSequence constraint, FilterResults results) {
            fitems = (ArrayList<Pkmn>)results.values;

            clear();
            int count = fitems.size();
            for (int i=0; i<count; i++)
            {
                Pkmn pkmn = (Pkmn)fitems.get(i);
                add(pkmn);
            }
        }

    }
}

Ciapas

what is the work of 'clear()' and 'add()' function. – Hammon

@compileGuy, what's mean "Pkmn"? I can not run this example. could you upload code completely? – Fillet

Excellent implementation @compileguy, add and clear are functionalities by adapter, you dont need to overide them. pkmn is a model class to hold the data values in list – Sloatman

How does your code fit in with mine (#20524917)? I am still having a problem :/ – Zeph

How you have set your Adapter in your listview @Ciapas – Linstock

Answer 1

Your problem are this lines:

this.original = items;
this.fitems = items;

Items is the list you use for your ListView and putting it in two different variables does not make two different lists out of it. You are only giving the list items two different names.

You can use:

this.fitems = new ArrayList(items);

that should generate a new List and changes on this list will only change the fitems list.

Edme

Not working for me, My ListView disappears and when I delete the entire string it doesn't come back again. #20524917 – Zeph

@SiKni8 me too getting the same result. please help – Linstock

Answer 2

you can accomplish the same effect by just creating a toString() method on your Pkmn class that returns the value you want to filter by.

Logger

Answer 3

The best way I found to to filter ArrayAdapter is to create my own filter class:

private class MyFilter extends Filter

then in that function create the new object array to display after the filter (you can find good implementation in the source code of class ArrayAdapter)

@Override
protected FilterResults performFiltering(CharSequence prefix)

now the trick is in this method

@Override
protected void publishResults(CharSequence constraint, FilterResults results)

when you use the Array adapter you can't do this:

myAdapterData = results.values

since then you disconnect your data from the super data, you must do this to keep your reference to the super original data array:

data.clear();
data.addAll((List<YourType>) results.values);

and then override

getFilter()

in your adapter, for example:

@Override
public Filter getFilter() {
    if (filter == null) {
        filter = new MyFilter();
    }
    return filter;
}

Underside

Answer 4

They have it covered here: https://www.mysamplecode.com/2012/07/android-listview-custom-layout-filter.html

You'll need to call clear() on the arrrat adapter to not hit the indexBoundException and add() on every element, since addAll() is valid only since honeycomb.

@SuppressWarnings("unchecked") @Override protected void publishResults(CharSequence constraint, FilterResults results) {

countryList = (ArrayList<Country>)results.values;
notifyDataSetChanged();
clear();
for(int i = 0, l = countryList.size(); i < l; i++)
 add(countryList.get(i));
notifyDataSetInvalidated();

}

Blucher