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android error FATAL EXCEPTION: AsyncTask #1

Help is needed, I just started learning to code and trying to create a product app but I encountered some errors.
Here is my class:
public class AllProductsActivity extends ListActivity {
// Progress Dialog
private ProgressDialog pDialog;
// Creating JSON Parser object
JSONParser jParser = new JSONParser();
ArrayList<HashMap<String, String>> productsList;
// url to get all products list
private static String url_all_products = "http://127.0.0.1/android_connect2/get_all_products.php";
// JSON Node names
private static final String TAG_SUCCESS = "success";
private static final String TAG_PRODUCTS = "products";
private static final String TAG_PID = "pid";
private static final String TAG_NAME = "name";
// products JSONArray
JSONArray products = null;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.all_products);
// Hashmap for ListView
productsList = new ArrayList<HashMap<String, String>>();
// Loading products in Background Thread
new LoadAllProducts().execute();
// Get listview
ListView lv = getListView();
// on seleting single product
// launching Edit Product Screen
lv.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// getting values from selected ListItem
String pid = ((TextView) view.findViewById(R.id.pid)).getText()
.toString();
// Starting new intent
Intent in = new Intent(getApplicationContext(),
EditProductActivity.class);
// sending pid to next activity
in.putExtra(TAG_PID, pid);
// starting new activity and expecting some response back
startActivityForResult(in, 100);
}
});
}
// Response from Edit Product Activity
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
// if result code 100
if (resultCode == 100) {
// if result code 100 is received
// means user edited/deleted product
// reload this screen again
Intent intent = getIntent();
finish();
startActivity(intent);
}
}
/**
* Background Async Task to Load all product by making HTTP Request
* */
class LoadAllProducts extends AsyncTask<String, String, String[]> {
/**
* Before starting background thread Show Progress Dialog
* */
#Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(AllProductsActivity.this);
pDialog.setMessage("Loading products. Please wait...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(false);
//pDialog.show();
}
/**
* getting All products from url
* */
protected String[] doInBackground(String... args) {
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
// getting JSON string from URL
JSONObject json = jParser.makeHttpRequest(url_all_products, "GET", params);
// Check your log cat for JSON response
Log.d("All Products: ", json.toString());
try {
// Checking for SUCCESS TAG
int success = json.getInt(TAG_SUCCESS);
if (success == 1) {
// products found
// Getting Array of Products
products = json.getJSONArray(TAG_PRODUCTS);
// looping through All Products
for (int i = 0; i < products.length(); i++) {
JSONObject c = products.getJSONObject(i);
// Storing each json item in variable
String id = c.getString(TAG_PID);
String name = c.getString(TAG_NAME);
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put(TAG_PID, id);
map.put(TAG_NAME, name);
// adding HashList to ArrayList
productsList.add(map);
}
} else {
// no products found
// Launch Add New product Activity
Intent i = new Intent(getApplicationContext(),
NewProductActivity.class);
// Closing all previous activities
i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(i);
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
/**
* After completing background task Dismiss the progress dialog
* **/
protected void onPostExecute(String file_url) {
// dismiss the dialog after getting all products
pDialog.dismiss();
// updating UI from Background Thread
runOnUiThread(new Runnable() {
public void run() {
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(
AllProductsActivity.this, productsList,
R.layout.list_item, new String[] { TAG_PID,
TAG_NAME},
new int[] { R.id.pid, R.id.name });
// updating listview
setListAdapter(adapter);
}
});
}
}
And my JSON parser:
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.equals("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.equals("GET")){
// request method is GET
DefaultHttpClient httpClient = new DefaultHttpClient();
String paramString = URLEncodedUtils.format(params, "utf-8");
url += "?" + paramString;
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();
} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
// try parse the string to a JSON object
try {
jObj = new JSONObject(json);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
// return JSON String
return jObj;
}
}
This is the error I'm getting:
E/Buffer Error: Error converting result java.lang.NullPointerException
E/JSON Parser: Error parsing data org.json.JSONException: End of input at character 0 of
E/AndroidRuntime: FATAL EXCEPTION: AsyncTask #1
Process: com.example.androidhive, PID: 3761
java.lang.RuntimeException: An error occurred while executing doInBackground()
at android.os.AsyncTask$3.done(AsyncTask.java:318)
at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:354)
at java.util.concurrent.FutureTask.setException(FutureTask.java:223)
at java.util.concurrent.FutureTask.run(FutureTask.java:242)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607)
at java.lang.Thread.run(Thread.java:761)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String org.json.JSONObject.toString()' on a null object reference
at com.example.androidhive.AllProductsActivity$LoadAllProducts.doInBackground(AllProductsActivity.java:130)
at com.example.androidhive.AllProductsActivity$LoadAllProducts.doInBackground(AllProductsActivity.java:105)
at android.os.AsyncTask$2.call(AsyncTask.java:304)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133) 
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607) 
at java.lang.Thread.run(Thread.java:761) 
Any help is appreciated, I have searched this site for solutions but each question is answered code-specific. Cheers

Because this line returns null JSONObject
JSONObject json = jParser.makeHttpRequest(url_all_products, "GET", params);
So check first that it's has null value or not before changing it into string
Like..
if (json != null && json.getInt(TAG_SUCCESS) != 0/*or failed value
*/){
// ALSO PARSE RESULT HERE
// Check your log cat for JSON response
Log.d("All Products: ", json.toString());
}else{
// SHOW NOTIFICIATION: URL/SERVER NOT REACHABLE
}
Hope this will help you.

How to pass Array as parameters with okhttp Library

I am using OKHttp dependency.I am not able to pass array to server in NamvaluePair paramenters.
This my function to send parameter in POST and Getting jSON in response.
public JSONObject getJSONFromUrl(String url, List<NameValuePair> params) throws IOException, JSONException {
OkHttpClient client = new OkHttpClient();
Log.i("PARAMETERS", "PARAMETERS ::" + params);
FormEncodingBuilder builder = new FormEncodingBuilder();
for (NameValuePair valuePair : params) {
builder.add(valuePair.name, URLEncoder.encode(valuePair.value, "UTF-8"));
}
Request request = new Request.Builder().url(url).post(builder.build()).build();
Log.i("Registration Request::", request.toString());
Response response = client.newCall(request).execute();
Log.i("REGISTRATION RESPONSE::", response.toString());
JSONObject jObj= new JSONObject(response.body().string()) ;
return jObj;
}
This is my Funtion to Call Action.
public JSONObject getShopCategory(String jsonArray) throws IOException {
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new NameValuePair("tag", categoryShopTag));
params.add(new NameValuePair(categoryShopTag, jsonArray));
// params.add(new BasicNameValuePair("buyer_id", buyer_id));
// params.add(new BasicNameValuePair("last_sync_date", last_sync_date));
Log.i("CATEGORY REQUEST::", params.toString());
// getting JSON Object
JSONObject json = null;
try {
json = jsonParser.getJSONFromUrl(UrlMap.urlPath, params);
} catch (JSONException e) {
e.printStackTrace();
}
return json;
}
This is from where i am calling the funtion.
for (int i = 0; i < sellerId.size(); i++) {
lastdateCat = "2011-02-11 18:57:25";
buyerCategoryFunction = new BuyerCategoryFunction();
JSONObject jsonObjectCategory = new JSONObject();
try {
jsonObjectCategory.put("shop_id", sellerId.get(i));
jsonObjectCategory.put("last_sync_date", lastdateCat);
jsonObjectCategory.put("buyer_id", CommonUtilities
.getSellerId(getApplicationContext()));
} catch (JSONException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
jsonCategoryArray.put(jsonObjectCategory);
}
JSONObject jsonCategory = buyerCategoryFunction
.getShopCategory(jsonCategoryArray.toString();
Issue is not from web service because its working fine with HttpClient.
Please help me to go thought.

JSONObject parsing

Here is the way i was going to do it but I get an error in the line JSONObject c = orders.getJSONObject(i);:
Error:(95, 57) error: incompatible types: int cannot be converted to String
Maybe there is a better way of doing this process , please help
#Override
protected String doInBackground(String... params) {
try {
List<NameValuePair> param = new ArrayList<NameValuePair>();
JSONObject json = jsonParser.makeHttpRequest(URL_ORDERS, "GET",
param, token);
JSONObject data = json.getJSONObject("data");
JSONObject orders = data.getJSONObject("orders");
Log.d("JSON DATA", data.toString());
Log.d("JSON ORDERS", orders.toString());
for (int i = 0; i < orders.length(); i++) {
JSONObject c = orders.getJSONObject(i);
imageurl = c.getString(TAG_IMAGE);
Log.d("IDK", imageurl);
title = c.getString(TAG_TITLE).substring(0, 20);
price = c.getString(TAG_PRICE);
status = c.getString(TAG_PSTATUS);
symbol = c.getString(TAG_PRICESYMBOL);
HashMap<String, String> map = new HashMap<String, String>();
map.put(TAG_TITLE, title);
map.put(TAG_PRICE, price);
map.put(TAG_PSTATUS, status);
map.put(TAG_PRICESYMBOL, symbol);
map.put(TAG_IMAGE, imageurl);
orderList.add(map);
}
} catch (JSONException e) {
e.printStackTrace();
}
}

Your orders object is a JSONObject (with the order IDs being used as keys and the complete order objects as values), but in your code you're treating it as a JSONArray.
You probably want to change your loop as follows:
Iterator<String> orderIterator = orders.keys();
while (orderIterator.hasNext()) {
JSONObject c = orders.getJSONObject(orderIterator.next());
// ...
}
The call to keys() will return an iterator over the object's keys (in this case order IDs). Then it's just a matter of using the iterator to loop over all the keys, and retrieve each order object using getJSONObject.

how to display graph in android using MySQL database

I can't get data from MySQL database for graphics. I found an example code for create graph but I want to put x axis data and y axis data from database
My example codes are:
public class Graph extends Activity {
private XYPlot xyPlot;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.graph);
// initialize our XYPlot reference:
xyPlot = (XYPlot) findViewById(R.id.xyplot);
Number[] income = {2000, 2500, 2700, 3000, 2800, 3500, 3700, 3800 };
Number[] expense = {2200, 2700, 2900, 2800, 2600, 3000, 3300, 3400 };
final String[] mMonths = new String[] {
"Jan","Feb", "Mar","Apr", "May","Jun",
"Jul", "Aug","Sep","Oct", "Nov","Dec"
};
// Converting the above income array into XYSeries
XYSeries incomeSeries = new SimpleXYSeries(
Arrays.asList(income), // array => list
SimpleXYSeries.ArrayFormat.Y_VALS_ONLY , // Y_VALS_ONLY means use the element index as the x value
"Income"); // Title of this series
// Converting the above expense array into XYSeries
XYSeries expenseSeries = new SimpleXYSeries(
Arrays.asList(expense), // array => list
SimpleXYSeries.ArrayFormat.Y_VALS_ONLY, // Y_VALS_ONLY means use the element index as the x value
"Expense"); // Title of this series
// Create a formatter to format Line and Point of income series
LineAndPointFormatter incomeFormat = new LineAndPointFormatter(
Color.rgb(0, 0, 255), // line color
Color.rgb(200, 200, 200), // point color
null ); // fill color (none)
// Create a formatter to format Line and Point of expense series
LineAndPointFormatter expenseFormat = new LineAndPointFormatter(
Color.rgb(255, 0, 0), // line color
Color.rgb(200, 200, 200), // point color
null); // fill color (none)
// add expense series to the xyplot:
xyPlot.addSeries(expenseSeries,expenseFormat);
// add income series to the xyplot:
xyPlot.addSeries(incomeSeries, incomeFormat);
// Formatting the Domain Values ( X-Axis )
xyPlot.setDomainValueFormat(new Format() {
#Override
public StringBuffer format(Object obj, StringBuffer toAppendTo, FieldPosition pos) {
return new StringBuffer( mMonths[ ( (Number)obj).intValue() ] );
}
#Override
public Object parseObject(String source, ParsePosition pos) {
return null;
}
});
xyPlot.setDomainLabel("");
xyPlot.setRangeLabel("Amount in Dollars");
// Increment X-Axis by 1 value
xyPlot.setDomainStep(XYStepMode.INCREMENT_BY_VAL, 1);
xyPlot.getGraphWidget().setRangeLabelWidth(50);
// Reduce the number of range labels
xyPlot.setTicksPerRangeLabel(2);
// Reduce the number of domain labels
xyPlot.setTicksPerDomainLabel(2);
// Remove all the developer guides from the chart
xyPlot.disableAllMarkup();
}
Get Database Codes:
public class AllProductsActivity extends ListActivity {
// Progress Dialog
private ProgressDialog pDialog;
// Creating JSON Parser object
JSONParser jParser = new JSONParser();
ArrayList<HashMap<String, String>> productsList;
// url to get all products list
private static String url_all_products = "http://10.0.2.2/android_connect/get_all_products.php";
// JSON Node names
private static final String TAG_SUCCESS = "success";
private static final String TAG_DEGERLER = "degerler";
private static final String TAG_SICAKLIK = "Sicaklik";
private static final String TAG_GERILIM = "Gerilim";
private static final String TAG_AKIM = "Akim";
private static final String TAG_REEL = "Reel Guc";
private static final String TAG_REAKTIF = "Reaktif Guc";
// products JSONArray
JSONArray products = null;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.all_products);
// Hashmap for ListView
productsList = new ArrayList<HashMap<String, String>>();
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
// getting JSON string from URL
JSONObject json = jParser.makeHttpRequest(url_all_products, "GET", params);
// Check your log cat for JSON response
Log.d("All Products: ", json.toString());
try {
// Checking for SUCCESS TAG
int success = json.getInt(TAG_SUCCESS);
if (success == 1) {
// products found
// Getting Array of Products
products = json.getJSONArray(TAG_DEGERLER);
// looping through All Products
for (int i = 0; i < products.length(); i++) {
JSONObject c = products.getJSONObject(i);
// Storing each json item in variable
String sicaklik = c.getString(TAG_SICAKLIK);
String gerilim = c.getString(TAG_GERILIM);
String akim = c.getString(TAG_AKIM);
String reel = c.getString(TAG_REEL);
String reaktif = c.getString(TAG_REAKTIF);
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put(TAG_SICAKLIK, sicaklik);
map.put(TAG_GERILIM, gerilim);
map.put(TAG_AKIM, akim);
map.put(TAG_REEL, reel);
map.put(TAG_REAKTIF, reaktif);
// adding HashList to ArrayList
productsList.add(map);
}
} else {
}
} catch (JSONException e) {
e.printStackTrace();
}
ListAdapter adapter = new SimpleAdapter(
AllProductsActivity.this, productsList,
R.layout.list_item, new String[] { TAG_SICAKLIK,
TAG_GERILIM,TAG_AKIM,TAG_REEL,TAG_REAKTIF},
new int[] { R.id.sicaklik, R.id.gerilim, R.id.akim, R.id.reel, R.id.reaktif});
// updating listview
setListAdapter(adapter);
}
}
JSON Parser Codes:
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 method
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;
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();
} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
// try parse the string to a JSON object
try {
jObj = new JSONObject(json);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
// return JSON String
return jObj;
}
}

Yeah, this just isn't going to work. Activity.onCreate is not main(). You can't just put your application there.
I'm sure this isn't what you want to hear, by you really need to go all the way back to the drawing board. You are going to want to put the code that requests the JSON object into a Service.
The code that does the actual graphing looks pretty good. You will need to set it up so that when the Service succeeds in retrieving the JSON, and then parsing it, it notifies the Activity that there is something to graph.
Step back from the code and brush up on Android architecture for a couple days. It isn't hard, but it is different.

Yes.It will be possible. you can follow my example
Bar Chart in Android With out any Built in jars. Here you can get data from database and try to set the results in the arrays(Say grossSal,netSal,datelabel arrays)
Here is the simple logic with no jars needed. you can implement bar charts with your own coding from this example

Issue in passing a string from one activity to another

Background : I am trying to develop my first android application which is a student discussion panel. I am good with PHP and MySQL but don't have much experience in android Java.
Issue:
In SelectedQuestionActivity class, if I simply give the URL as http://thewbs.getfreehosting.co.uk/talky/fetchans.php?qid=3, it works just fine and it fetches the corresponding answer to the question.
But if I do it the way I have shown in the code below, the application crashes. I am not sure where I am wrong.
CODE:
AllQuestionActivity.java
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// getting values from selected ListItem
String pid = ((TextView) view.findViewById(R.id.qid)).getText()
.toString();
//pid is the value of the selected question for example www.example.com/fetchans?qid=3 so here pid value is supposed to be 3.
// Starting new intent
Intent in = new Intent(getApplicationContext(),
SelectedQuestionActivity.class);
// sending pid to next activity
in.putExtra(TAG_PID, pid);
startActivity(in);
}
});
Now in SelectedQuestionActivity.java
code:
public class SelectedQuestionActivity extends ListActivity {
// Progress Dialog
private ProgressDialog pDialog;
// Creating JSON Parser object
JSONParser jParser = new JSONParser();
ArrayList<HashMap<String, String>> productsList;
Intent intent = getIntent();
String qid = intent.getExtras().getString(TAG_PID);
// url to get all products list
private String url_all_products = "http://thewbs.getfreehosting.co.uk/talky/fetchans.php?qid="+qid;
// JSON Node names
private static final String TAG_SUCCESS = "success";
private static final String TAG_PRODUCTS = "ques";
private static final String TAG_PID = "aid";
private static final String TAG_NAME = "aname";
private static final String TAG_INFO = "answer";
private static final String TAG_DATE = "date";
// products JSONArray
JSONArray products = null;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.all_ans);
// Hashmap for ListView
productsList = new ArrayList<HashMap<String, String>>();
// Loading products in Background Thread
new LoadAllProducts().execute();
// Get listview
ListView lv = getListView();
}
class LoadAllProducts extends AsyncTask<String, String, String> {
/**
* Before starting background thread Show Progress Dialog
* */
#Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(SelectedQuestionActivity.this);
pDialog.setMessage("Loading Answers. Please wait...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(false);
pDialog.show();
}
protected String doInBackground(String... args) {
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
// getting JSON string from URL
JSONObject json = jParser.makeHttpRequest(url_all_products, "GET", params);
// Check your log cat for JSON reponse
Log.d("All Answers: ", json.toString());
try {
// Checking for SUCCESS TAG
int success = json.getInt(TAG_SUCCESS);
if (success == 1) {
// products found
products = json.getJSONArray(TAG_PRODUCTS);
// looping through All Products
for (int i = 0; i < products.length(); i++) {
JSONObject c = products.getJSONObject(i);
// Storing each json item in variable
String id = c.getString(TAG_PID);
String name = c.getString(TAG_NAME);
String info = c.getString(TAG_INFO);
String date = c.getString(TAG_DATE);
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put(TAG_PID, id);
map.put(TAG_NAME, name);
map.put(TAG_INFO, info);
map.put(TAG_DATE, date);
// adding HashList to ArrayList
productsList.add(map);
}
}
else {
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
/**
* After completing background task Dismiss the progress dialog
* **/
protected void onPostExecute(String file_url) {
// dismiss the dialog after getting all products
pDialog.dismiss();
// updating UI from Background Thread
runOnUiThread(new Runnable() {
public void run() {
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(
SelectedQuestionActivity.this, productsList,
R.layout.list_selected_ques, new String[] { TAG_PID,
TAG_NAME, TAG_INFO, TAG_DATE },
new int[] { R.id.aid, R.id.aname, R.id.answer, R.id.date});
// updating listview
setListAdapter(adapter);
}
});
}
}
}
JSONparser.java
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 method
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;
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();
} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
// try parse the string to a JSON object
try {
jObj = new JSONObject(json);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
// return JSON String
return jObj;
}
}

Currently you are trying to getIntent outside onCreate of ListActivity so move it inside onCreate method as :
Intent intent;
String qid;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.all_ans);
// get Intent here
intent = getIntent();
qid = intent.getExtras().getString(TAG_PID);
// your code here
and also no need to use runOnUiThread method for updating UI from onPostExecute because onPostExecute method called on Ui thread we can access UI elements in it
EDIT:-
you are not adding any paramter to NameValuePair inside doInBackground . add quid before sending it to makeHttpRequest as :
protected String doInBackground(String... args) {
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
add quid param here
params.add(new BasicNameValuePair("qid",qid)); //<<<< add here
// getting JSON string from URL
JSONObject json = jParser.makeHttpRequest(
url_all_products,
"GET",
params);
// your code here

You are passing a string from one activity object to another , while you didn't write code to receive it on the new activity in the right place.
To solve this you should add some code to your onCreate:
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.all_ans);
String url = getIntent().getStringExtra(TAG_PID);
if (url != null)
url_all_products = url;

You should need to get your intent values in onCreate() as below :
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.all_ans);
Intent intent = getIntent();
String qid = intent.getExtras().getString(TAG_PID);
}