How Can I Filter Custom ArrayList

Question

How to implement Filter in a Custom ArrayList using EditText, I am parsing JSON data into ListView using an ArrayList.

I would like to allow user to filter records using Person Name or City in EditText

public class Persons {

    private String name;
    private String city;

    .......

    // getters and setters

}

PersonsAdapter.java:

public class PersonsAdapter extends BaseAdapter implements Filterable {

ArrayList<Persons> arrayList;
ArrayList<Persons> filteredItems;
LayoutInflater inflater;
int Resource;
ViewHolder holder;
Context context;

private ItemFilter mFilter = new ItemFilter();

public PersonsAdapter(Context context, int resource, ArrayList<Persons> arrayList) {
    this.context = context;
    this.inflater = (LayoutInflater) context
            .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    this.Resource = resource;
    this.arrayList = arrayList;
    this.filteredItems = arrayList;
}


@Override
public View getView(final int position, View convertView, ViewGroup parent) {
    // convert view = design
    View view = convertView;
    if (view == null) {
        holder = new ViewHolder();
        view = inflater.inflate(Resource, null);

        holder.textName = (TextView) view.findViewById(R.id.textName);
        holder.textCity = (TextView) view.findViewById(R.id.textCity);


        view.setTag(holder);
    }
    else 
    {
        holder = (ViewHolder) view.getTag();
    }


    holder.textName.setText(arrayList.get(position).getName());
    holder.textCity.setText(arrayList.get(position).getCity());

    return view;

}

static class ViewHolder {

    TextView textName;
    TextView textCity;

}

public Filter getFilter() {
    return mFilter;
}

private class ItemFilter extends Filter {
    @Override
    protected FilterResults performFiltering(CharSequence constraint) {
        constraint = constraint.toString().toLowerCase();
        FilterResults result = new FilterResults();
        filteredItems = new ArrayList<Persons>();
        if (constraint != null && constraint.toString().length() > 0) {

            for (int i = 0, l = arrayList.size(); i < l; i++) {
                Persons person = arrayList.get(i);

                // here check with your property
                if (person.getName().toLowerCase().contains(constraint))
                    filteredItems.add(person);
            }
            result.count = filteredItems.size();
            result.values = filteredItems;
        } else {
            synchronized (this) {
                result.values = arrayList;
                result.count = arrayList.size();
            }
        }
        return result;
    }

    @SuppressWarnings("unchecked")
    @Override
    protected void publishResults(CharSequence constraint, FilterResults results) {
        filteredItems = (ArrayList<Persons>) results.values;
        notifyDataSetChanged();
    }
}


@Override
public int getCount() {
    // TODO Auto-generated method stub
    return arrayList.size();
}


@Override
public Object getItem(int position) {
    // TODO Auto-generated method stub
    return arrayList.get(position);
}


@Override
public long getItemId(int position) {
    // TODO Auto-generated method stub
    return position;
}

}

Answer 1

Try to use below code to solve your problem and learn for correct implementation for Filterable interface

Replace below line from your existing code not to instantiate every time

private ItemFilter mFilter = new ItemFilter();

To

private ItemFilter mFilter;

private class ItemFilter extends Filter {
        @Override
        protected FilterResults performFiltering(CharSequence constraint) {
            FilterResults results = new FilterResults();

            if (constraint != null && constraint.length() > 0) {
                ArrayList<Persons> filterList = new ArrayList<Persons>();
                for (int i = 0; i < filteredItems.size(); i++) {

                    Persons person = filteredItems.get(i);
                    String name = person.getName().toUpperCase();
                    String city = person.getCity().toUpperCase();
                    if (name.contains(constraint.toString().toUpperCase()) || city.contains(constraint.toString().toUpperCase())) {

                        filterList.add(person);
                    }
                }
                results.count = filterList.size();
                results.values = filterList;
            } else {
                results.count = filteredItems.size();
                results.values = filteredItems;
            }
            return results;

        }

        @Override
        protected void publishResults(CharSequence constraint,
                FilterResults results) {
            arrayList  = (ArrayList<Persons>) results.values;
            notifyDataSetChanged();
        }

    }

 public Filter getFilter() {
     if (itemFilter == null) {
         itemFilter = new ItemFilter();
     }
     return itemFilter;
 }

 @Override
 public long getItemId(int position) {
     return arrayList.indexOf(getItem(position));
 }