Json.java

package com.kustomrtr.dolarparalelovenezuela;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.HashMap;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.app.Activity;
import android.content.Context;
import android.os.AsyncTask;
import android.util.Log;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;

public class Json extends AsyncTask<String, Float, JSONObject> {

  private String json_url = "";
	private MainActivity myMainActivity;
	private Context contexto;
	private Activity activity;

	public Json(MainActivity activity) {
		myMainActivity = activity;
		this.activity = activity;
		contexto = myMainActivity.getApplicationContext();
	}

	public JSONObject getJSON(String url) {

		// inicialización
		InputStream is = null;
		String result = "";
		JSONObject jArray = null;

		// http post
		HttpClient httpclient = new DefaultHttpClient();
		HttpPost httppost = new HttpPost(url);
		HttpResponse response = null;
		try {
			response = httpclient.execute(httppost);
		} catch (ClientProtocolException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		HttpEntity entity = response.getEntity();
		try {
			is = entity.getContent();
		} catch (IllegalStateException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

		// convertir respuesta a string
		BufferedReader reader = null;
		try {
			reader = new BufferedReader(
					new InputStreamReader(is, "iso-8859-1"), 8);
		} catch (UnsupportedEncodingException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		StringBuilder sb = new StringBuilder();
		String line = null;
		try {
			while ((line = reader.readLine()) != null) {
				sb.append(line + "\n");
			}
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		try {
			is.close();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		result = sb.toString();

		// parseando string a un objeto JSON
		try {
			jArray = new JSONObject(result);
		} catch (JSONException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

		return jArray;
	}

	protected void onPreExecute() {
		Toast toast = Toast.makeText(contexto, "Ejecutando thread",
				Toast.LENGTH_LONG);
		toast.show();
	}

	@Override
	protected JSONObject doInBackground(String... uri) {
		json_url = uri[0];
		JSONObject jstring = null;

		try {

			jstring = this.getJSON(uri[0]);
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

		return jstring;
	}

	@Override
	protected void onProgressUpdate(Float... progress) {
		Toast toast = Toast.makeText(contexto, "Progreso: " + progress[0],
				Toast.LENGTH_LONG);
		toast.show();
	}

	@Override
	protected void onPostExecute(JSONObject result) {

		/*
		 * Toast toast = Toast.makeText(contexto, "Thread terminado. ",
		 * Toast.LENGTH_LONG); toast.show();
		 */

		// Arraylist initialitation
		ArrayList<HashMap<String, String>> lista = new ArrayList<HashMap<String, String>>();


		// Array of strings "titulos"
		String titulos[] = { "Dolar (Transferencia)", "Euro (Transferencia)",
				"Dolar (Efectivo)", "Euro (Efectivo)", "Dolar (cúcuta)",
				"Euro (cucuta)" };

		try {
			JSONObject json = result; // result is a JSONObject and the source is located here: https://dl.dropbox.com/u/8102604/dolar.json
			JSONObject root = json.getJSONObject("root"); 
			JSONArray items = root.getJSONArray("item");
			int j = 0; 

			for (int i = 0; i < items.length(); i++) {
				JSONObject item = items.getJSONObject(i);
				String key = item.getString("key");
				String mount = item.getString("mount");
				if (key.equals("TS") || key.equals("TE") || key.equals("EE")
						|| key.equals("CE") || key.equals("ES")
						|| key.equals("CS")) { // i did this since i only need the items where the key is equal to TS, TE, EE, CE, ES or CS.
					HashMap<String, String> map = new HashMap<String, String>();
					map.put("id", String.valueOf(i));
					map.put(key, mount);
					lista.add(map);
					System.out.println(titulos[j] + "(" + key + "). BsF = " + mount); // just for debugging purposes
					j++; // add 1 to j if key is equal to TS, TE, EE, CE, ES or CS. In this way i can associate the two arrays (item and titulos)
				}
			}

			ListView lv = (ListView) myMainActivity.findViewById(R.id.listView1); // create a list view 
			lv.setAdapter(new ArrayAdapter<String>(contexto, android.R.layout.simple_list_item_1, lista)); // set adapter to the listview (not working)

		} catch (JSONException e) {
			Log.e("log_tag", "Error parsing data " + e.toString());
		}
	}
}

MainActivity.java

package com.kustomrtr.dolarparalelovenezuela;

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

public class MainActivity extends Activity {

  @Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		new Json(this).execute("http://192.168.1.5/dolar.json");

	} // on create

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.activity_main, menu);
		return true;
	}

}