JSON android problem !

This program wants to connect to web server in this case i use WAMP then i create file food.php in www, and i connect my request from activity to get data from database (WAMP).

When i run it force to close ! WHY ? Here the code !!

JSON.java

package org.example;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;

import org.apache.http.HttpEntity;
import org.a开发者_如何学JAVApache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
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.app.ListActivity;
import android.net.ParseException;
import android.os.Bundle;
import android.util.Log;
import android.widget.Toast;

public class JSON extends ListActivity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
     setContentView(R.layout.main);
     String result = null;
     InputStream is = null;
     StringBuilder sb=null;

    //http post
     try{
        HttpClient httpclient = new DefaultHttpClient();
        HttpPost httppost = new HttpPost("http://127.0.0.1/food.php");

        List<NameValuePair> nvp = new ArrayList<NameValuePair>();

        httppost.setEntity(new UrlEncodedFormEntity(nvp));
        HttpResponse response = httpclient.execute(httppost);
        HttpEntity entity = response.getEntity();
        is = entity.getContent();
     }catch(Exception e){
        Log.e("log_tag", "Error in http connection"+e.toString());
     }

     //convert response to string
     try{
        BufferedReader reader = new BufferedReader(new InputStreamReader(is,"iso-8859-1"),8);
        sb = new StringBuilder();
        sb.append(reader.readLine() + "\n");
        String line="0";

        while ((line = reader.readLine()) != null) {
            sb.append(line + "\n");
        }

        is.close();
        result=sb.toString();

     }catch(Exception e){
        Log.e("log_tag", "Error converting result "+e.toString());
     }

     //paring data
     int fd_id;
     String fd_name;
     try{
        JSONArray jArray = new JSONArray(result);
        JSONObject json_data=null;

        for(int i=0;i<jArray.length();i++){
            json_data = jArray.getJSONObject(i);
            fd_id=json_data.getInt("FOOD_ID");
            fd_name=json_data.getString("FOOD_NAME");
        }

     }catch(JSONException e1){
        Toast.makeText(getBaseContext(), "No Food Found", Toast.LENGTH_LONG).show();
     }catch (ParseException e1){
        e1.printStackTrace();
     }
}

}

HERE my main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<ListView
android:id="@android:id/list"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>

<TextView  
android:layout_width="fill_parent" 
android:layout_height="wrap_content" 
android:text="@string/hello"
/>
</LinearLayout>

Here is log cat :

07-13 10:21:41.324: ERROR/AndroidRuntime(280): FATAL EXCEPTION: main
07-13 10:21:41.324: ERROR/AndroidRuntime(280): java.lang.RuntimeException: Unable to start activity ComponentInfo{org.example/org.example.JSON}: java.lang.NullPointerException
07-13 10:21:41.324: ERROR/AndroidRuntime(280):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
07-13 10:21:41.324: ERROR/AndroidRuntime(280):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
07-13 10:21:41.324: ERROR/AndroidRuntime(280):     at android.app.ActivityThread.access$2300(ActivityThread.java:125)
07-13 10:21:41.324: ERROR/AndroidRuntime(280):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
07-13 10:21:41.324: ERROR/AndroidRuntime(280):     at android.os.Handler.dispatchMessage(Handler.java:99)
07-13 10:21:41.324: ERROR/AndroidRuntime(280):     at android.os.Looper.loop(Looper.java:123)
07-13 10:21:41.324: ERROR/AndroidRuntime(280):     at android.app.ActivityThread.main(ActivityThread.java:4627)
07-13 10:21:41.324: ERROR/AndroidRuntime(280):     at java.lang.reflect.Method.invokeNative(Native Method)
07-13 10:21:41.324: ERROR/AndroidRuntime(280):     at java.lang.reflect.Method.invoke(Method.java:521)
07-13 10:21:41.324: ERROR/AndroidRuntime(280):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
07-13 10:21:41.324: ERROR/AndroidRuntime(280):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
07-13 10:21:41.324: ERROR/AndroidRuntime(280):     at dalvik.system.NativeStart.main(Native Method)
07-13 10:21:41.324: ERROR/AndroidRuntime(280): Caused by: java.lang.NullPointerException
07-13 10:21:41.324: ERROR/AndroidRuntime(280):     at org.json.JSONTokener.nextCleanInternal(JSONTokener.java:112)
07-13 10:21:41.324: ERROR/AndroidRuntime(280):     at org.json.JSONTokener.nextValue(JSONTokener.java:90)
07-13 10:21:41.324: ERROR/AndroidRuntime(280):     at org.json.JSONArray.<init>(JSONArray.java:87)
07-13 10:21:41.324: ERROR/AndroidRuntime(280):     at org.json.JSONArray.<init>(JSONArray.java:103)
07-13 10:21:41.324: ERROR/AndroidRuntime(280):     at org.example.JSON.onCreate(JSON.java:74)
07-13 10:21:41.324: ERROR/AndroidRuntime(280):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
07-13 10:21:41.324: ERROR/AndroidRuntime(280):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
07-13 10:21:41.324: ERROR/AndroidRuntime(280):     ... 11 more

You should not create json array from result but create json object from result and then take array from it. Here you can find more info: http://www.androidcompetencycenter.com/2009/10/json-parsing-in-android/