Problème login Android

Bonsoir à tous
j'ai du problème dans mon code suivant:

require 'conn.php';
//$username='nn';
//$pass='nn';
 $query = "SELECT * FROM users";// where user_name='$username' and password='$pass' ";
$final_data = array();   
if ($query_run = mysql_query($query))
    {
        $i=0;
        $id ;
        while($query_row = mysql_fetch_assoc($query_run))
        {
          $id =$query_row ['user_id'];
         $i++; 
        }
         if( $i==0)
        {
$data = array('state' => '0', 'id' => 'Noid');
print (json_encode($data));
       }
         else {
$data = array('state' => '1', 'id' => ''.$id);
print (json_encode($data));
}

    }else{
     echo mysql_error();
    } 

package com.example.tourisme;

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.List;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.ResponseHandler;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.BasicResponseHandler;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import com.example.a1.R;

import android.app.Activity;
import android.app.AlertDialog;
import android.app.ProgressDialog;
import android.*******.DialogInterface;
import android.*******.DialogInterface.OnCancelListener;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends Activity {
    private Button connexion1;
    private EditText username,password;
    public ProgressDialog progressDialog;
    public  String user,pass;
    HttpPost httppost;
    StringBuffer buffer;
    HttpResponse response;
    HttpClient httpclient;
    List<NameValuePair> nameValuePairs;
    ProgressDialog dialog = null;

    private static String url = "http://10.0.0.2/android_connect/check.php";
    String result = null;
    InputStream is = null;
    JSONObject json_data=null;
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        set*******View(R.layout.activity_main);
        connexion1 = (Button) findViewById(R.id.connexion);
        username = (EditText) findViewById(R.id.name);
        password = (EditText) findViewById(R.id.pass);

        connexion1.setOnClickListener(new View.OnClickListener()
        {

                public void onClick(View v)
            {

                    String aa="nn";
                    String aa2="nn";
                    HttpClient httpclient = new DefaultHttpClient();
                    HttpPost httppost = new HttpPost("http://192.168.36.201/android_connect/check.php?username="+aa+"&pass="+aa2+"");

             try {

             HttpResponse response = httpclient.execute(httppost);
             String jsonResult = inputStreamToString(response.getEntity().get*******()).toString();
             JSONObject object = new JSONObject(jsonResult);

             String name = object.getString("state");
                  String verion = object.getString("id");
                  //textView.setText(name + " - " + verion);
                  int chk=Integer.parseInt(name);
                  if(chk==1)
                  {
                      showAlert("you are login"+"success  login thank you.");

                  }
                  else
                  {showAlert("no login"+"error  login please check user name or password ");
                  }

             }
             catch (JSONException e) {
                 Log.e("maconnexion_internet","Erreur de récupération des données",e);
             }
             catch (ClientProtocolException e) {
                 Log.e("maconnexion_internet","Erreur de récupération des données",e);
             }
             catch (IOException e) {
                 Log.e("maconnexion_internet","Erreur de récupération des données",e);
             }

            }

        });

    }

    private StringBuilder inputStreamToString(InputStream is) {
        String rLine = "";
        StringBuilder answer = new StringBuilder();
        BufferedReader rd = new BufferedReader(new InputStreamReader(is));

        try {
         while ((rLine = rd.readLine()) != null) {
          answer.append(rLine);
           }
        }

        catch (IOException e) {
            e.printStackTrace();
         }
        return answer;

    }

     public void showAlert(final String h){
         MainActivity.this.runOnUiThread(new Runnable() {
             public void run() {
                 AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
                 builder.setTitle("Login Error.");
                 builder.setMessage(h)  
                        .setCancelable(false)
                        .setPositiveButton("OK", new DialogInterface.OnClickListener() {
                            public void onClick(DialogInterface dialog, int id) {
                            }
                        });                       
                 AlertDialog alert = builder.create();
                 alert.show();                
             }
         });
     }

    } 

quand je clique sur le bouton connexion rien ne se passe
où est le problème