I am unable to get any result from my code.please suggest the solution for my problem, here is my code and thanks in Advance

CODE: Activity.main

 public class MainActivity extends Activity {

 ArrayList<detail> country =  new ArrayList<detail>();

 class detail{
    public String toponymName;
    public String countrycode;
    public int population;
    public String wikipedia;
    }

   Adapter ad = null;
   static ArrayList<string> resultrow;

   protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    new HttpAsyncTask().execute("http://api.geonames.org/citiesJSON?        north=44.1&south=-9.9&east=-22.4&west=55.2&lang=de&username=demo");

    ListView mylistview = (ListView)findViewById(R.id.mylistview);
    ad = new Adapter();
    mylistview.setAdapter(ad);

    }
    public static String GET(String url){
    InputStream inputStream = null;
    String result = "";
    try {
         HttpClient httpclient = new DefaultHttpClient();
         HttpResponse httpResponse = httpclient.execute(new HttpGet(url));
         inputStream = httpResponse.getEntity().getContent();
         if(inputStream != null)
            result = convertInputStreamToString(inputStream);
        else
            result = "Did not work!";

    } catch (Exception e) {
        Log.d("InputStream", e.getLocalizedMessage());}
         return result;
    }

    private static String convertInputStreamToString(InputStream inputStream) throws IOException{
    BufferedReader bufferedReader = new BufferedReader( new InputStreamReader(inputStream));
    String line = "";
    String result = "";
    while((line = bufferedReader.readLine()) != null){
        Log.e("Line",line);
         result += line;
    }
     inputStream.close();
    return result;
    }

    private class HttpAsyncTask extends AsyncTask<String, Void, String> {
    @Override
    protected String doInBackground(String... urls) {

        return GET(urls[0]);
    }
    @Override
    protected void onPostExecute(String result) {
        Toast.makeText(getBaseContext(), "Received!", Toast.LENGTH_LONG).show();
        String strJson = result;

        try {
           JSONObject  jsonRootObject = new JSONObject(strJson);
           JSONArray jsonArray = jsonRootObject.optJSONArray("geonames");
           for(int i=0; i < jsonArray.length(); i++){
               JSONObject jsonObject = jsonArray.getJSONObject(i);
               detail resultrow = new detail();
               resultrow.toponymName =jsonObject.getString("toponymName");
               resultrow.countrycode =jsonObject.getString("countrycode");
               resultrow.wikipedia =jsonObject.getString("wikipedia");
               resultrow.population =jsonObject.getInt("population");
               country.add(resultrow);
       }

        }
           catch (JSONException e) {e.printStackTrace();}
    } 

    }
    class Adapter extends ArrayAdapter<detail>{
    Adapter(){
                  super(MainActivity.this,android.R.layout.simple_list_item_1,country);
    }
    public View getview(int position,View convertview,ViewGroup parent){
        viewHolder holder;

    if(convertview==null){
        LayoutInflater inflater = getLayoutInflater();
        convertview=inflater.inflate(R.layout.row, null);
        holder = new viewHolder(convertview);
        convertview.setTag(holder);
    }
    else{
        holder=(viewHolder)convertview.getTag();
    }
    holder.populateFrom(country.get(position));
    return convertview;
    }
    }
    class viewHolder{
    public TextView toponymName=null;
    public TextView countrycode=null;
    public TextView wikipedia=null;
    public TextView population=null;

    viewHolder(View row){
        toponymName =(TextView)row.findViewById(R.id.toponymName);
        countrycode =(TextView)row.findViewById(R.id.countrycode);
        wikipedia =(TextView)row.findViewById(R.id.wikipedia);
        population =(TextView)row.findViewById(R.id.population);
        }

      //not able to populate this block
       void populateFrom(detail r){
        toponymName.setText(r.toponymName);
        countrycode.setText(r.countrycode);
        wikipedia.setText(r.wikipedia);
        population.setText(r.population);
    }
    }
    }

sometimes also get this error :

{"status":{"message":"the daily limit of 30000 credits for demo has been exceeded. Please use an application specific account. Do not use the demo account for your application.","value":18}}

please tell me what is this error

I still don't know that why you are using this pojo concept here.

Anyway , I can only suggest you do add some getter/setter in side the class. like

class detail{
    public String toponymName;
    public String countrycode;
    public int population;
    public String wikipedia;
    public String getToponymName() {
        return toponymName;
    }
    public void setToponymName(String toponymName) {
        this.toponymName = toponymName;
    }
    public String getCountrycode() {
        return countrycode;
    }
    public void setCountrycode(String countrycode) {
        this.countrycode = countrycode;
    }
    public int getPopulation() {
        return population;
    }
    public void setPopulation(int population) {
        this.population = population;
    }
    public String getWikipedia() {
        return wikipedia;
    }
    public void setWikipedia(String wikipedia) {
        this.wikipedia = wikipedia;
    }

    }

It will help you to set and get particular data from JSON String.

Something like:

   JSONObject jsonObject = jsonArray.getJSONObject(i);
           detail resultrow = new detail();
           resultrow.setToponymName(jsonObject.getString("toponymName");
          ..........
          .......
           country.add(resultrow);

When you want to set it:: Just do

toponymName.setText(r.getToponymName());
..................................
..................................

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