Search field in Blackberry

When user click on a specific Alphabet key, then it will show the country name that have the starting letter corresponding to the Key pressed.



package mypackage;

import net.rim.device.api.collection.util.SortedReadableList;
import net.rim.device.api.ui.Field;
import net.rim.device.api.ui.MenuItem;
import net.rim.device.api.ui.component.Dialog;
import net.rim.device.api.ui.component.EditField;
import net.rim.device.api.ui.component.KeywordFilterField;
import net.rim.device.api.ui.component.KeywordProvider;
import net.rim.device.api.ui.container.MainScreen;
import net.rim.device.api.util.Comparator;
import net.rim.device.api.util.StringUtilities;

public final class MyScreen extends MainScreen
{
    KeywordFilterField _keywordFilterField;
    CountryList _countryList;
public MyScreen(){
 _countryList = new CountryList();
        _countryList.addElement(new Country("Zimbabwe"));
        _countryList.addElement(new Country("Argentina"));
        _countryList.addElement(new Country("Brazil"));
        _countryList.addElement(new Country("Canada"));
        _countryList.addElement(new Country("Chile"));
        _countryList.addElement(new Country("China"));
        _countryList.addElement(new Country("Germany"));
    
        _keywordFilterField = new KeywordFilterField(){
             protected boolean navigationClick(int status, int time) {
                 int index = getSelectedIndex();
               
                 String str = (((Country) getElementAt(index)).toString());
                 Dialog.alert(str);
               
                return true;
             }
        };
        _keywordFilterField.setLabel("");
        _keywordFilterField.setSourceList(_countryList, _countryList);
          add(_keywordFilterField);
      }
 
}

class CountryList extends SortedReadableList implements KeywordProvider
{
    public CountryList()
    {
        super(new CountryListComparator());    
    }

    void addElement(Object element)
    {
        doAdd(element);    
    }
 
    public String[] getKeywords(Object element)
    {
        if(element instanceof Country)
        {
            return StringUtilities.stringToWords(element.toString());
        }
        return null;
    }

    final static class CountryListComparator implements Comparator
    {
        public int compare(Object o1, Object o2)
        {
            if (o1 == null || o2 == null)
                throw new IllegalArgumentException("Cannot compare null countries");
     
            return o1.toString().compareTo(o2.toString());
        }
    }
 
}

class Country
{
    private String _countryName;
 
    public Country(String countryName)
    {
        _countryName = countryName;    
    }
 
    public String toString()
    {
        return _countryName;
    }
  

}