Android ArrayAdapter Example

package com.myapp;

import android.os.Bundle;
import android.app.Activity;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;

public class MainActivity extends Activity  {
    
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
       
        // listView1
        final ListView lisView1 = (ListView)findViewById(R.id.listView1); 
        	
		CountryList country_data[] = new CountryList[]
		        {
		            new CountryList("1","TH","Thailand"),
		            new CountryList("2","VN","Vietnam"),
		            new CountryList("3","ID","Indonesia"),
		            new CountryList("4","LA","Laos"),
		            new CountryList("5","MY","Malaysia")
		        };
       
		CountryAdapter adapter = new CountryAdapter(this, 
                R.layout.activity_column, country_data);
		
		lisView1.setAdapter(adapter);
		
    }
    
    public class CountryList {
        public String ID;
        public String Code;
        public String Country;
        public CountryList(){
            super();
        }
        
        public CountryList(String ID, String Code, String Country) {
            super();
            this.ID = ID;
            this.Code = Code;
            this.Country = Country;
        }
    }
    
    public class CountryAdapter extends ArrayAdapter<CountryList> 
    {
	 	Context context; 
	    CountryList country_data[] = null;
    	    
        public CountryAdapter(Context c, int textViewResourceId,CountryList[] data) {
        	super(c, R.layout.activity_column, data);
        	context = c;
        	country_data = data;
		}

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

		public View getView(final int position, View convertView,
				ViewGroup parent) {
			// TODO Auto-generated method stub
			CountryHolder holder = null;

			if (convertView == null) {
				
				LayoutInflater inflater = (LayoutInflater) context
						.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
				 convertView = inflater.inflate(R.layout.activity_column, null);

				holder = new CountryHolder();
				holder.ID = (TextView) convertView.findViewById(R.id.ColID);
				holder.Code = (TextView) convertView.findViewById(R.id.ColCode);
				holder.Country = (TextView) convertView.findViewById(R.id.ColCountry);

				convertView.setTag(holder);
			} else {
				holder = (CountryHolder) convertView.getTag();
			}

			CountryList country = country_data[position];
	        holder.ID.setText(country.ID);
	        holder.Code.setText(country.Code);
	        holder.Country.setText(country.Country);
	        
			return convertView;

		}

    }
    
	public class CountryHolder {
		TextView ID;
		TextView Code;
		TextView Country;
	}

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }
    
}