Develop Reference

Json file data parsing from URL in Android Studio

I have a problem with this Json file. I am trying to do a Parser that shows in a textview the results after a button is pressed. I wonna parse the "firstName" tag but to do this, I need to pass through the others tags like "league" and "standard". I don't know how to parse them in this Json file.
The Json file is structured like this:
{
"_internal":{
"pubDateTime":"2017-06-23 03:21:52.076",
"xslt":"xsl/league/roster/marty_active_players.xsl",
"eventName":"league_roster"
},
"league":{
"standard":[
{
"firstName":"Alex",
"lastName":"Abrines",
"personId":"203518",
"teamId":"1610612760 1610612760",
"jersey":"8",
"pos":"G-F",
"heightFeet":"6",
"heightInches":"6",
"heightMeters":"1.98",
"weightPounds":"190",
"weightKilograms":"86.2",
"dateOfBirthUTC":"1993-08-01",
"teams":[
{
"teamId":"1610612760",
"seasonStart":"2016",
"seasonEnd":"2016"
}
],
"draft":{
"teamId":"1610612760",
"pickNum":"32",
"roundNum":"2",
"seasonYear":"2013"
},
"nbaDebutYear":"2016",
"yearsPro":"0",
"collegeName":"",
"lastAffiliation":"Spain/Spain",
"country":"Spain"
},
This is my Java code:
public class MainActivity extends AppCompatActivity {
Button btnHit;
TextView txtJson;
ProgressDialog pd;
String Players[] = new String[100];
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btnHit = (Button) findViewById(R.id.btn);
txtJson = (TextView) findViewById(R.id.tvJsonItem);
btnHit.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
new JsonTask().execute("http://data.nba.net/10s/prod/v1/2016/players.json");
}
});
}
private class JsonTask extends AsyncTask<String, String, String> {
protected void onPreExecute() {
super.onPreExecute();
pd = new ProgressDialog(MainActivity.this);
pd.setMessage("Please wait");
pd.setCancelable(false);
pd.show();
}
protected String doInBackground(String... params) {
HttpURLConnection connection = null;
BufferedReader reader = null;
try {
URL url = new URL(params[0]);
connection = (HttpURLConnection) url.openConnection();
connection.connect();
InputStream stream = connection.getInputStream();
reader = new BufferedReader(new InputStreamReader(stream));
StringBuffer buffer = new StringBuffer();
String line = "";
while ((line = reader.readLine()) != null) {
buffer.append(line + "\n");
Log.d("Response: ", "> " + line); //here u ll get whole response...... :-)
}
return buffer.toString();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (connection != null) {
connection.disconnect();
}
try {
if (reader != null) {
reader.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
return null;
}
#Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
try {
JSONObject jsonObject = new JSONObject(result);
String DataPlayers = jsonObject.getString("standard");
JSONArray jsonArray = new JSONArray(DataPlayers);
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject JO = jsonArray.getJSONObject(i);
Players[i] = JO.getString("firstName");
txtJson.append(Players[i] + "\n");
}
} catch (JSONException e) {
e.printStackTrace();
}
if (pd.isShowing()) {
pd.dismiss();
}
}
}

Wrong:
JSONObject jsonObject = new JSONObject(result);
String DataPlayers = jsonObject.getString("standard");
Correct:
JSONObject jsonObject = new JSONObject(result);
JsonObject objStandard = jsonObject.getJSONObject("league");
Now from objStandard object, you can retrieve the json array and iterate through the sub json objects.
JSONArray jsonArray = objStandard.getJSONArray("standard");
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject JO = jsonArray.getJSONObject(i);
Players[i] = JO.getString("firstName");
txtJson.append(Players[i] + "\n");
}
2 cents suggestion :)
It seems you have just started exploring android development, saying based on you are using a legacy method of json parsing, I would suggest you to check out GSON library, which is a Java serialization/deserialization library to convert Java Objects into JSON and back. In short, you will not be needed to parse JSON response manually but rather you will be having normal java class objects and members/methods to deal with.

Your code should be like this
try {
String result = "your_json_string";
JSONObject jsonObject = new JSONObject(result);
JSONObject leagueObject = jsonObject.getJSONObject("league");
JSONArray standardArray = leagueObject.getJSONArray("standard");
for (int i = 0; i < standardArray.length(); i++) {
JSONObject standardObject = standardArray.getJSONObject(i);
String name = standardObject.getString("firstName");
}
} catch (Exception e) {
System.out.println(e);
}

android jsonObject Null Pointer Exception [duplicate]

This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 6 years ago.
I am new to JSON. I need help. My android studio keeps on telling me that my jsonobject is NULL. I can parse and display my jsonarray into a listview. But when i click the page where i displayed it, my app crashes.
Parser
class BgTask extends AsyncTask<Void, Void, String> {
String json_url;
#Override
protected void onPreExecute() {
json_url = "http://10.0.2.2/result/hehe.php";
}
#Override
protected String doInBackground(Void... params) {
try {
URL url = new URL(json_url);
HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
InputStream inputstream = httpURLConnection.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputstream));
StringBuilder stringBuilder = new StringBuilder();
while ((JSON_STRING = bufferedReader.readLine()) != null) {
stringBuilder.append(JSON_STRING + "\n");
}
bufferedReader.close();
inputstream.close();
httpURLConnection.disconnect();
return stringBuilder.toString().trim();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
#Override
protected void onProgressUpdate(Void... values) {
super.onProgressUpdate(values);
}
#Override
protected void onPostExecute(String result) {
json_string = result;
}
}
public void publishGame(View view)
{
if(json_string == null)
{
Toast.makeText(getApplicationContext(), "Get Data First",Toast.LENGTH_SHORT).show();
}
else
{
Intent intent = new Intent(this, Games.class);
intent.putExtra("json_data", json_string);
startActivity(intent);
}
}
}
code that posts
Bundle intent=getIntent().getExtras();
if(intent !=null) {
json_string = intent.getString("json_data");
json_string = getIntent().getExtras().getString("json_data");
}
try {
jsonObject = new JSONObject(json_string);
jsonArray = jsonObject.getJSONArray("server_response");
int count = 0;
String team1, score1, team2, score2, Type;
while (count < jsonArray.length()) {
JSONObject JO = jsonArray.getJSONObject(count);
team1 = JO.getString("team1");
score1 = JO.getString("score1");
team2 = JO.getString("team2");
score2 = JO.getString("score2");
Type = JO.getString("Type");
Downloader downloader = new Downloader(team1, score1, team2, score2, Type);
gamesAdapter.add(downloader);
count++;
}
} catch (JSONException e) {
e.printStackTrace();
}
}
The error pointing is here try {
jsonObject = new JSONObject(json_string);

The error is because you are trying to parse "json_data" to JSONObject which is not a valid json. Perhaps you are having server response in a variable called json_data which is of String type if that is the case you need to pass that variable instead of passing String literal into JSONObject constructor.

how to fetch json object from url in android

I want to fetch json data from json object.
My json data is:{"avg":2.5} and my android code is
public class AsyncTaskParseJson extends AsyncTask < String, String, String > {
final String TAG = "AsyncTaskParseJson.java";
// set your json string url here
String yourJsonStringUrl = "http://www.bsservicess.com/photoUpload/star_avg.php?bookName=" + book_name;
// contacts JSONArray
#Override
protected void onPreExecute() {}
#Override
protected String doInBackground(String...arg0) {
try {
JSONParser jParser = new JSONParser();
// get json string from url
JSONObject json = jParser.getJSONFromUrl(yourJsonStringUrl);
// get the array of users
JSONObject dataJsonArr = json.getJSONObject(str);
String c = dataJsonArr.getString("avg");
na = c;
starts = Float.parseFloat(c);
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(String strFromDoInBg) {
super.onPostExecute(strFromDoInBg);
netRate.setRating(starts);
Toast.makeText(mybookview.this, Float.toString(starts), Toast.LENGTH_SHORT).show();
}
But somehow its not working.I have trie every tutorial and evrything but nothing works.plz help me

your getting the json data in response is as {"avg":2.5}
simple remove the below code
JSONObject dataJsonArr = json.getJSONObject(str);
String c = dataJsonArr.getString("avg");
with below line
String c = json.getString("avg");

this is for simple get data from url example:
Parse JSON from HttpURLConnection object
and if you want use library then try Volley:
tutorial link:
http://www.androidhive.info/2014/05/android-working-with-volley-library-1/

A very simple solution to your problem
String str = "{ \"avg\" :0 }";
JsonParser parser = new JsonParser();
JsonObject object = (JsonObject) parser.parse(str);
String value = object.get("avg").getAsString();
But first of all you have to correct the warning in your backend.
EDIT the complete solution
public class AsyncTaskParseJson extends AsyncTask < String, String, String > {
HttpURLConnection urlConnection;
#Override
protected String doInBackground(String...args) {
StringBuilder result = new StringBuilder();
try {
URL url = new URL("http://www.bsservicess.com/photoUpload/star_avg.php?bookName=" + book_name);
urlConnection = (HttpURLConnection) url.openConnection();
InputStream in = new BufferedInputStream(urlConnection.getInputStream());
BufferedReader reader = new BufferedReader(new InputStreamReader( in ));
String line;
while ((line = reader.readLine()) != null) {
result.append(line);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
urlConnection.disconnect();
}
return result.toString();
}
#Override
protected void onPostExecute(String result) {
JsonParser parser = new JsonParser();
JsonObject object = (JsonObject) parser.parse(result);
String value = object.get("avg").getAsString();
}
}
But first of all remove the warning from the web response!

Android - retrieving json via HTTPS

I've a problem with parsing json from facebook graph api.
When I'm using facebook URL:https://graph.facebook.com/interstacjapl/feed?access_token=MyTOKEN to grab json it's no working, but when I copied that json (it works in browser) and paste to my webiste http://mywebsite/fb.json and change site URL in the code, it works good.
When I'm using fb graph URL it shows error:
W/System.err(5534): org.json.JSONException: No value for data
Is this problem with parsing from https or URL or code?
JSONParser.java
public class JSONParser {
static InputStream is = null;
static JSONObject jObj = null;
static String json = "";
// constructor
public JSONParser() {
}
public JSONObject getJSONFromUrl(String url) {
// Making HTTP request
try {
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
HttpResponse httpResponse = httpClient.execute(httpPost);
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;
}
}
MainActivity
public class MainActivity extends Activity {
ListView list;
TextView ver;
TextView name;
TextView api;
Button Btngetdata;
ArrayList<HashMap<String, String>> oslist = new ArrayList<HashMap<String, String>>();
//URL to get JSON Array
private static String url = "https://graph.facebook.com/interstacjapl/feed?access_token=CAACEdEose0cBANLR...";
//JSON Node Names
private static final String TAG = "data";
private static final String TAG_ID = "id";
private static final String TAG_NAME = "message";
private static final String TAG_API = "type";
JSONArray android = null;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
oslist = new ArrayList<HashMap<String, String>>();
Btngetdata = (Button)findViewById(R.id.getdata);
Btngetdata.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
new JSONParse().execute();
}
});
}
private class JSONParse extends AsyncTask<String, String, JSONObject> {
private ProgressDialog pDialog;
#Override
protected void onPreExecute() {
super.onPreExecute();
ver = (TextView)findViewById(R.id.vers);
name = (TextView)findViewById(R.id.name);
api = (TextView)findViewById(R.id.api);
pDialog = new ProgressDialog(MainActivity.this);
pDialog.setMessage("Getting Data ...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}
#Override
protected JSONObject doInBackground(String... args) {
JSONParser jParser = new JSONParser();
// Getting JSON from URL
JSONObject json = jParser.getJSONFromUrl(url);
return json;
}
#Override
protected void onPostExecute(JSONObject json) {
pDialog.dismiss();
try {
// Getting JSON Array from URL
android = json.getJSONArray(TAG);
for(int i = 0; i < android.length(); i++){
JSONObject c = android.getJSONObject(i);
// Storing JSON item in a Variable
String ver = c.getString(TAG_ID);
String name = c.getString(TAG_NAME);
String api = c.getString(TAG_API);
// Adding value HashMap key => value
HashMap<String, String> map = new HashMap<String, String>();
map.put(TAG_ID, ver);
map.put(TAG_NAME, name);
map.put(TAG_API, api);
oslist.add(map);
list=(ListView)findViewById(R.id.list);
ListAdapter adapter = new SimpleAdapter(MainActivity.this, oslist,
R.layout.list_v,
new String[] { TAG_ID,TAG_NAME, TAG_API }, new int[] {
R.id.vers,R.id.name, R.id.api});
list.setAdapter(adapter);
list.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
Toast.makeText(MainActivity.this, "You Clicked at "+oslist.get(+position).get("name"), Toast.LENGTH_SHORT).show();
}
});
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
}

This works
String reply = "";
BufferedReader inStream = null;
HttpClient httpClient = new DefaultHttpClient();
HttpGet httpRequest = new HttpGet(url);
try {
HttpResponse response = httpClient.execute(httpRequest);
inStream = new BufferedReader(
new InputStreamReader(
response.getEntity().getContent()));
StringBuffer buffer = new StringBuffer("");
String line = "";
while ((line = inStream.readLine()) != null) {
buffer.append(line);
}
inStream.close();
reply = buffer.toString();
} catch (Exception e) {
//Handle Execptions
}

How to make onPostExecute() or Json parsing work?

I am a beginner in Android, and I am writing a short program to download a JSON feed from URL and parse it. I use AsyncTask to do the downloading.
The doInBackground() part seems to work well. Then I set my breakpoint to onPostExecute(), it can even stop at parseJSON(result), and 'result' is showing the correct json string downloaded. But when I try to step into parseJSON(result), it will NOT step into the function correctly(either throw JSONException directly or go to some random lines within parseJSON(result)).
From DDMS log it's not showing any valuable information as well.
How might I find what the problem is? Is it because I used onPostExecute() incorrectly, or parseJSON() has some problem?
public class MainActivity extends Activity {
private listItem[] items;
public class listItem {
String title;
String description;
String imageHref;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
items = new listItem[50];
new DownloadJsonFeed().execute("http://dl.dropbox.com/u/10168342/facts.json");
}
private class DownloadJsonFeed extends AsyncTask<String, Void, String> {
#Override
protected String doInBackground(String... params) {
try {
return downloadUrl(params[0]);
} catch (IOException e) {
return "Unable to retrieve json feed. URL may be invalid.";
}
}
#Override
protected void onPostExecute(String result) {
try {
parseJSON(result); // Here !!!!!!
} catch (JSONException e) {
}
}
}
private String downloadUrl(String myurl) throws IOException {
InputStream is = null;
try {
URL url = new URL(myurl);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setReadTimeout(10000 /* milliseconds */);
conn.setConnectTimeout(15000 /* milliseconds */);
conn.setRequestMethod("GET");
conn.setDoInput(true);
conn.connect();
is = conn.getInputStream();
// Convert the InputStream into a string
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line);
}
is.close();
return sb.toString();
} finally {
if (is != null) {
is.close();
}
}
}
private void parseJSON(String feed) throws JSONException {
JSONObject json_obj = new JSONObject(feed);
title = json_obj.getString("title");
String rows = json_obj.getString("rows");
JSONArray jArray = new JSONArray(rows);
for (int i = 0; i < jArray.length(); i++) {
JSONObject tmp = jArray.getJSONObject(i);
items[i].title = tmp.getString("title");
items[i].description = tmp.getString("description");
items[i].imageHref = tmp.getString("imageHref");
}
}

JSONObject.getString() will try to get String type value, but what you want is array type.

I think you didn't get the JSON array right. The json_obj.getString will give you an String instead an array.
Try to change as follows:
private void parseJSON(String feed) throws JSONException {
JSONObject json_obj = new JSONObject(feed);
title = json_obj.getString("title");
String rows = json_obj.getString("rows");
JSONArray jArray = json_obj.getJSONArray("rows"); //<---- change this line
for (int i = 0; i < jArray.length(); i++) {
JSONObject tmp = jArray.getJSONObject(i);
items[i].title = tmp.getString("title");
items[i].description = tmp.getString("description");
items[i].imageHref = tmp.getString("imageHref");
}
}