Null Pointer Exception In Method Boolean.Org.Json.Jsonobject Do in background async task

I designed app to make order for pizza food restaurant
I show userid,menu id ,address,longtiude,latitude then press on button make order
Error show after I press button and found in async task doin background
It give me fatal exception error
An error occurred while executing doInBackground()
and it show to me two lines have proplem
AddNewOrder.doInBackground(Summary.java:113)
AddNewOrder.doInBackground(Summary.java:77)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean org.json.JSONObject.getBoolean(java.lang.String)' on a null object reference

package com.pizza_final_project_app.pizza_final_project;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.AsyncTask;
import android.preference.PreferenceManager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONException;
import org.json.JSONObject;

import java.util.ArrayList;
import java.util.List;

public class Summary extends Activity {
SharedPreferences preferences;
private ProgressDialog pDialog;
//JSONParser jsonParser = new JSONParser();
boolean errorFound;
TextView textaddress;
TextView textlongtiude;
TextView textlatitude;
TextView text2;
TextView textuser;
Button btnorder;
private static final String TAG_SUCCESS = "success";
private static final String TAG = Summary.class.getSimpleName();

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_summary);
text2=(TextView)findViewById(R.id.textView3);
textaddress=(TextView)findViewById(R.id.textaddress);
textuser=(TextView)findViewById(R.id.textView4);
textlongtiude=(TextView)findViewById(R.id.textlongtiude);
textlatitude=(TextView)findViewById(R.id.textlatitude);
Intent i = getIntent();
String id = i.getStringExtra("Data4");
String address = i.getStringExtra("Data8");
String longtiude = i.getStringExtra("Data9");
String latitude = i.getStringExtra("Data10");
text2.setText(id);
textaddress.setText(address);
textlongtiude.setText(longtiude);
textlatitude.setText(latitude);
preferences= PreferenceManager.getDefaultSharedPreferences(getApplicationContext());

String email=preferences.getString("email","");
textuser.setText(email);
pDialog = new ProgressDialog(this);
pDialog.setCancelable(false);
btnorder=(Button)findViewById(R.id.button2);
btnorder.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v)
{
addOrder(textuser.getText().toString().trim(), text2.getText().toString().trim(),
textaddress.getText().toString().trim(), textlongtiude.getText().toString().trim(),
textlatitude.getText().toString().trim());

}
});


}
//line 77
class AddNewOrder extends AsyncTask<String, String, String> {

@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(Summary.this);
pDialog.setMessage("Making Order...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}

protected String doInBackground(String... args) {
final JSONParser jsonParser = new JSONParser();
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("userID", args[0]));
params.add(new BasicNameValuePair("menuID", args[1]));
params.add(new BasicNameValuePair("address", args[2]));
params.add(new BasicNameValuePair("longitude", args[3]));
params.add(new BasicNameValuePair("latitude", args[4]));


JSONObject jObj = jsonParser.makeHttpRequest(AppConfig.URL_Order,
"POST", params);

try {
//Line 113
boolean error = jObj.getBoolean("error"); 
if (!error) {

errorFound=false;
} else {
errorFound=true;

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

return null;
}
protected void onPostExecute(String file_url) {
if (pDialog.isShowing()) {
pDialog.dismiss();
if (!errorFound){
Toast.makeText(getApplicationContext(), "User successfully registered. Try login now!", Toast.LENGTH_LONG).show();


Intent intent = new Intent(
Summary.this,
FinalResult.class);
startActivity(intent);
finish();
}
else{
Toast.makeText(getApplicationContext(), "An Error occoured!", Toast.LENGTH_LONG).show();

}
}
}

}
*/
private void addOrder(final String userID, final String menuID, final String address,
final String longitude, final String latitude) {

new AddNewOrder().execute(userID, menuID, address, longitude, latitude);

}

}

Class AppConfig

package com.pizza_final_project_app.pizza_final_project;

public class AppConfig {

public static String URL_Order = "xxxx.";

json parser

package com.pizza_final_project_app.pizza_final_project;

import android.util.Log;

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.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.utils.URLEncodedUtils;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.util.List;

public class JSONParser {

static InputStream is = null;
static JSONObject jObj = null;
static String json = "";

// constructor
public JSONParser() {

}

// function get json from url
// by making HTTP POST or GET mehtod
public JSONObject makeHttpRequest(String url, String method,
List<NameValuePair> params) {

// Making HTTP request
try {

// check for request method
if(method == "POST"){
// request method is POST
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
httpPost.setEntity(new UrlEncodedFormEntity(params));

HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();

}else if(method == "GET"){
// request method is GET
DefaultHttpClient httpClient = new DefaultHttpClient();
String paramString = URLEncodedUtils.format(params, "utf-8");
url += "?" + paramString;
Log.d("data",url);
HttpGet httpGet = new HttpGet(url);

HttpResponse httpResponse = httpClient.execute(httpGet);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
} 


} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}

try {
BufferedReader reader = new BufferedReader(new InputStreamReader(
is, "iso-8859-1"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
json = sb.toString();
Log.d("json","data is "+json);

} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
try {
jObj = new JSONObject(json);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}

// return JSON String
return jObj;

}
}

thank you for reply
the error found in this line
boolean error = jObj.getBoolean("error"); 113
class AddNewOrder extends AsyncTask77
the error show in these two lines
what i make to remove error