Retrieving JSON Data using extras as a parameter of a constructor

Retrieving JSON Data using extras as a parameter of a constructor - android

Hi guys I am trying to retrieve some movie information in JSON format but I cannot seem to work out what the problem of my code is. The data retrieving and processing itself all works but the problem is that when I pass my title input in the EditText and retrieve that data from another activity, I cannot seem to be able to utilize it. I passed the extra retrieved into the parameter of my data processing class ParseJsonData. However, I get a null pointer exception at where I set title.setText(parseJsonData.getMovie().getTitle()). The strange aspect of this is that if I just run ParseJsonData in the MainActivity by passing in the title myself, I am able to retrieve the title of the data, observed through log. Is there anything that I should be aware of when I am passing an extra as a parameter of a constructor?
public class ResultsPage extends AppCompatActivity {
private final String LOG_TAG = getClass().getSimpleName();
private TextView title;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_results_page);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
setTextViews();
}
private void setTextViews () {
Bundle bundle = getIntent().getExtras();
String movieTitle = bundle.getString("title");
Log.v(LOG_TAG, "title recieved is : " + movieTitle);
ParseJsonData parseJsonData = new ParseJsonData(movieTitle);
parseJsonData.execute();
title.setText(parseJsonData.getMovie().getTitle());
}
}
Below is ParseJsonData
public class ParseJsonData extends GetRawData{
private String mUrl;
private String title;
private static final String LOG_TAG = "ParseJsonData";
private Movie movie;
public ParseJsonData(String title) {
this.title = title;
processUrl();
}
#Override
public void execute() {
super.setUrl(mUrl);
ParseJsonDataBackground parseJsonDataBackground = new ParseJsonDataBackground();
parseJsonDataBackground.execute(mUrl);
}
public Movie getMovie() {
return movie;
}
private void processUrl () {
final String BASE_URL = "http://www.omdbapi.com/";
final String MOVIE_TITLE = "t";
final String MOVIE_YEAR = "y";
final String MOVIE_PLOT = "plot";
final String MOVIE_DATA_TYPE = "r";
mUrl = Uri.parse(BASE_URL).buildUpon().appendQueryParameter(MOVIE_TITLE, title).appendQueryParameter(MOVIE_YEAR, "").appendQueryParameter(MOVIE_PLOT, "short").appendQueryParameter(MOVIE_DATA_TYPE, "json").build().toString();
Log.v(LOG_TAG, "New Url address is : " + mUrl);
}
public class ParseJsonDataBackground extends GetRawDataBackground {
#Override
protected String doInBackground(String... params) {
return super.doInBackground(params);
}
#Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
processData(getmData());
}
private void processData (String mData){
try {
final String MOVIE_TITLE = "Title";
JSONObject jsonObject = new JSONObject(mData);
Log.v(LOG_TAG, mData);
String title = jsonObject.getString(MOVIE_TITLE);
movie = new Movie(title);
Log.v(LOG_TAG, "Title of the movie is " + movie.getTitle());
}catch (JSONException e){
Log.e(LOG_TAG, "Error retrieving JsonData");
e.printStackTrace();
}
}
}
}
This is an extension of GetRawData which is below
public class GetRawData {
private String url;
private String mData;
private static final String LOG_TAG = "GetRawData";
public GetRawData() {
}
public String getmData() {
return mData;
}
public void setUrl(String url) {
this.url = url;
}
public void execute () {
GetRawDataBackground getRawDataBackground = new GetRawDataBackground();
getRawDataBackground.execute(url);
}
public class GetRawDataBackground extends AsyncTask<String, Void, String>{
private StringBuffer stringBuffer;
#Override
protected String doInBackground(String... params) {
mData = processDownloads (params[0]);
if (mData == null){
Log.e(LOG_TAG, "Null returned during processing");
return null;
}
return mData;
}
#Override
protected void onPostExecute(String s) {
Log.v(LOG_TAG, "Data retrieved is : " + s);
super.onPostExecute(s);
}
private String processDownloads (String mUrl){
HttpURLConnection connection = null;
BufferedReader reader = null;
try {
if (mUrl == null){
return null;
}
URL url = new URL(mUrl);
connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("GET");
int responseCode = connection.getResponseCode();
Log.d(LOG_TAG, "Response code is : " + responseCode);
reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
stringBuffer = new StringBuffer();
String line = new String();
while ((line = reader.readLine()) != null) {
stringBuffer.append(line);
}
return stringBuffer.toString();
} catch (MalformedURLException e) {
Log.e(LOG_TAG, "MalformedURLException");
return null;
} catch (IOException e){
Log.e(LOG_TAG, "IOException in making connection");
return null;
} finally {
if (connection != null) {
connection.disconnect();
}
if (reader != null) {
try {
reader.close();
} catch (IOException e) {
Log.e(LOG_TAG, "Error attempting to close reader");
}
}
}
}
}
}

It's because you're instantiating movie in the background task. It happens in a parallel thread (Thread 2). Your main thread calls getMovite().getTitle(); but movie is not set yet as Thread 2 is still running.
You should pass a callback to ParseJsonData from MainActivity and call the callback in onPostExecute. Make sure you return to the MainThread when you update the text view though.
public class ParseJsonDataBackground extends GetRawDataBackground {
public interface ParseJsonCallback{
void onJsonReady(Movie movie);
}
private ParseJsonCallback callback;
ParseJsonDataBackground(ParseJsonCallback callback){
this.callback = callback;
}
.....
#Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
processData(getmData());
callback.onJsonReady(movie);
}
.....
}
And in MainActivity
....
ParseJsonData parseJsonData = new ParseJsonData(movieTitle, new ParseJsonCallback(){
void onJsonReady(Movie movie){
runOnUiThread(new Runnable() {
#Override
public void run() {
title.setText(movie.getTitle());
}
});
}
});
parseJsonData.execute();
....

Related

Error handling of empty json in android studio

I am trying to build a simple news app that fetches news headlines from the internet but I am facing some problems in doing this.
In my app if my if the json is not parsed I just get an empty recycler view. In this case I want to parse the json again can someone please help me in doing this
This is my MainActivity:
public class MainActivity extends AppCompatActivity {
private MainActivityViewModel mainActivityViewModel;
private RecyclerView recyclerView;
private RecyclerViewAdapter adapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
recyclerView = findViewById(R.id.news_view);
mainActivityViewModel = ViewModelProviders.of(this).get(MainActivityViewModel.class);
mainActivityViewModel.init();
mainActivityViewModel.getNews().observe(this, new Observer<List<NewsData>>() {
#Override
public void onChanged(List<NewsData> newsData) {
adapter.notifyDataSetChanged();
}
});
init();
}
private void init(){
Log.d("","=========================intializing Recycler view======================");
System.out.println("executing init()");
adapter = new RecyclerViewAdapter(mainActivityViewModel.mutableLiveData.getValue(), this);
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
recyclerView.setLayoutManager(linearLayoutManager);
recyclerView.setAdapter(adapter);
}
}
This is NewsRepository.java
public class NewsRepository {
MutableLiveData<List<NewsData>> liveNews = new MutableLiveData<>();
private static NewsRepository instance;
public static NewsRepository getInstance(){
if(instance != null)
return instance;
instance = new NewsRepository();
return instance;
}
private static final String LOG_TAG = "NewsRepository";
private static final String newsAPIurl = "https://newsapi.org/v2/top-headlines?sources=google-news-in&apiKey";
List<NewsData> newsDatalist = new ArrayList<>();
public void getLiveNews(){
new FetchJSONAsyncTask().execute();
}
public class FetchJSONAsyncTask extends AsyncTask<Void,Void,Void>{
#Override
protected Void doInBackground(Void... voids) {
Log.d("Backgroumd thread" , "Fetching json");
URL url = createUrl();
String jsonRespone = "";
try {
jsonRespone = makeHttpRequest(url);
}
catch (IOException e) {
Log.d("Background" , "Could not Load url");
}
extractNewsfromJSON(jsonRespone);
return null;
}
}
private URL createUrl() {
URL url = null;
try {
url = new URL(NewsRepository.newsAPIurl);
} catch (MalformedURLException exception) {
Log.e(LOG_TAG, "Error with creating URL", exception);
return null;
}
return url;
}
private String makeHttpRequest(URL url) throws IOException {
String jsonResponse = "";
HttpURLConnection urlConnection = null;
InputStream inputStream = null;
try {
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.setReadTimeout(10000);
urlConnection.setConnectTimeout(15000);
urlConnection.connect();
inputStream = urlConnection.getInputStream();
jsonResponse = readFromStream(inputStream);
} catch (IOException e) {
Log.e(LOG_TAG,"there was an error in makeHTTPRequest" , e);
} finally {
if (urlConnection != null) {
urlConnection.disconnect();
}
if (inputStream != null) {
inputStream.close();
}
}
return jsonResponse;
}
private String readFromStream(InputStream inputStream) throws IOException {
StringBuilder output = new StringBuilder();
if (inputStream != null) {
InputStreamReader inputStreamReader = new InputStreamReader(inputStream, StandardCharsets.UTF_8);
BufferedReader reader = new BufferedReader(inputStreamReader);
String line = reader.readLine();
while (line != null) {
output.append(line);
line = reader.readLine();
}
}
return output.toString();
}
private void extractNewsfromJSON(String newsJSON){
try{
JSONObject jsonObject = new JSONObject(newsJSON);
String a = jsonObject.getString("status");
System.out.println("=================================================");
System.out.println(a);
JSONArray newsArray = jsonObject.getJSONArray("articles");
if(newsArray.length() > 0){
for(int i =0 ;i< newsArray.length();i++){
JSONObject article = newsArray.getJSONObject(i);
String title = article.getString("title");
String desc = article.getString("description");
String urltoimg = article.getString("urlToImage");
String readmore = article.getString("url");
NewsData obj = new NewsData(title , desc, readmore , urltoimg);
newsDatalist.add(obj);
}
}
} catch (JSONException e) {
Log.e(LOG_TAG, "Problem parsing the JSON results", e);
}
}
}
And this is MainActivityViewModel
public class MainActivityViewModel extends ViewModel {
private NewsRepository instance;
MutableLiveData<List<NewsData>> mutableLiveData;
public void init(){
if(instance != null)
return;
instance = NewsRepository.getInstance();
instance.getLiveNews();
mutableLiveData = instance.liveNews;
}
public LiveData<List<NewsData>> getNews(){
return mutableLiveData;
}
public void refreshNews(){
instance.getLiveNews();
}
}

Problem with you code lies in this function:
public MutableLiveData<List<NewsData>> getLiveNews(){
new FetchJSONAsyncTask().execute();
MutableLiveData<List<NewsData>> liveNews = new MutableLiveData<>();
System.out.println("==========================================");
liveNews.setValue(newsData);
return liveNews;
}
FetchJSONAsyncTask is an asynchronous task, you are returning liveNews before the data is fetched from the API. It's blank and hence you are getting empty RecyclerView.
Here is what you can do, Create liveNews a class variable instead of creating a new object each time.
public class NewsRepository {
public MutableLiveData<List<NewsData>> liveNews = new MutableLiveData<>();
//rest of the code
Update your ViewModel to directly get the value from this variable:
public class MainActivityViewModel extends ViewModel {
private NewsRepository instance;
LiveData<List<NewsData>> LiveData;
public void init(){
if(instance != null)
return;
instance = NewsRepository.getInstance();
LiveData = instance.liveNews;
instance.getLiveNews() // call to fetch JSON first time
}
public LiveData<List<NewsData>> getNews(){
return LiveData;
}
//call this function from your activity to refresh the data
public void refreshNews(){
instance.getLiveNews();
}
}
Now you update your getLiveNews method to just call FetchJSONAsyncTask.
public void getLiveNews(){
new FetchJSONAsyncTask().execute();
}
Now in extractNewsfromJSON method set the value of liveNews:
private void extractNewsfromJSON(String newsJSON){
try{
//rest of the code
liveNews.postValue(newsData);
}
} catch (JSONException e) {
System.out.println(newsJSON);
Log.e(LOG_TAG, "Problem parsing the JSON results", e);
}
}

Why is it not showing all the data?

I am creating this app which shows the latest news, which gets data from
https://newsapi.org/s/india-health-news-api
but it doesn't fetch all the data. Sometimes it just shows all but sometimes it just shows 2 or 3 news. Also, I don't see any log error message. What is the problem?
HealthNews.java
public class HealthNews extends AppCompatActivity {
private ArrayList urlList;
private NewsAdapter mNewsAdapter;
private static final String REQUEST_URL ="https://newsapi.org/v2/top-headlines?country=in&category=health&apiKey=3f7d99cdbb004766892bd239a4c099be";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_health_news);
Intent intent = getIntent();
HealthNews.NewsAsyncTask task = new HealthNews.NewsAsyncTask();
task.execute(REQUEST_URL);
urlList = QueryUtils.m;
ListView listView = (ListView)findViewById(R.id.listViewHealthNews);
mNewsAdapter = new NewsAdapter(this, new ArrayList<News>());
listView.setAdapter(mNewsAdapter);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
//Toast.makeText(getApplicationContext(), ""+ a.get(position), Toast.LENGTH_SHORT).show();
Object url = urlList.get(position);
Uri uri = (Uri) Uri.parse((String) url); // missing 'http://' will cause crashed
Intent intent = new Intent(Intent.ACTION_VIEW, uri);
startActivity(intent);
}
});
}
private class NewsAsyncTask extends AsyncTask<String, Void, ArrayList<News>> {
ProgressDialog p;
#Override
protected ArrayList<News> doInBackground(String... urls) {
if (urls.length < 1 || urls[0] == null) {
return null;
}
ArrayList<News> result = QueryUtils.fetchEarthquakeData(urls[0]);
return result;
//return null;
}
#Override
protected void onPostExecute(ArrayList<News> data) {
mNewsAdapter.clear();
if (data != null && !data.isEmpty()) {
p.hide();
mNewsAdapter.addAll(data);
}
}
#Override
protected void onPreExecute() {
super.onPreExecute();
p = new ProgressDialog(HealthNews.this);
p.setMessage("Latest News...");
p.setIndeterminate(false);
p.show();
}
}
}
QueryUtils.java
private static final String LOG_TAG = "";
private QueryUtils(){
}
private static URL createUrl(String stringUrl) {
URL url = null;
try {
url = new URL(stringUrl);
} catch (MalformedURLException e) {
Log.e(LOG_TAG, "Problem building the URL ", e);
}
return url;
}
private static String makeHttpRequest(URL url) throws IOException {
String jsonResponse = "";
// If the URL is null, then return early.
if (url == null) {
return jsonResponse;
}
HttpURLConnection urlConnection = null;
InputStream inputStream = null;
try {
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setReadTimeout(30000 /* milliseconds */);
urlConnection.setConnectTimeout(60000 /* milliseconds */);
urlConnection.setRequestMethod("GET");
urlConnection.connect();
if (urlConnection.getResponseCode() == 200) {
inputStream = urlConnection.getInputStream();
jsonResponse = readFromStream(inputStream);
} else {
Log.e(LOG_TAG, "Error response code: " + urlConnection.getResponseCode());
}
} catch (IOException e) {
Log.e(LOG_TAG, "Problem retrieving the earthquake JSON results.", e);
} finally {
if (urlConnection != null) {
urlConnection.disconnect();
}
if (inputStream != null) {
inputStream.close();
}
}
return jsonResponse;
}
private static String readFromStream(InputStream inputStream) throws IOException {
StringBuilder output = new StringBuilder();
if (inputStream != null) {
InputStreamReader inputStreamReader = new InputStreamReader(inputStream, Charset.forName("UTF-8"));
BufferedReader reader = new BufferedReader(inputStreamReader);
String line = reader.readLine();
while (line != null) {
output.append(line);
line = reader.readLine();
}
}
return output.toString();
}
static ArrayList<String> m = new ArrayList<String>();
public static ArrayList<News> extractNews(String SAMPLE_JSON){
if (TextUtils.isEmpty(SAMPLE_JSON)) {
return null;
}
ArrayList<News> news = new ArrayList<News>();
try {
JSONObject jsonObject1 = new JSONObject(SAMPLE_JSON);
JSONArray baseJSONArray = jsonObject1.getJSONArray("articles");
for (int i = 0; i < baseJSONArray.length(); i++) {
JSONObject jsonObject = baseJSONArray.getJSONObject(i);
JSONObject source = jsonObject.getJSONObject("source");
String name = source.getString("name");
String article = jsonObject.getString("title");
String url1 = jsonObject.getString("url");
String img = jsonObject.getString("urlToImage");
URL url = new URL(img);
Bitmap image = BitmapFactory.decodeStream(url.openConnection().getInputStream());
News a = new News(image, article);
news.add(a);
m.add(url1);
}
} catch (JSONException j) {
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return news;
}
public static ArrayList<News> fetchEarthquakeData(String requestUrl) {
URL url = createUrl(requestUrl);
String jsonResponse = null;
try {
jsonResponse = makeHttpRequest(url);
} catch (IOException e) {
Log.e(LOG_TAG, "Problem making the HTTP request.", e);
}
ArrayList<News> news = extractNews(jsonResponse);
return news;
}

I went though your code and found some issues.
Some bad practices i found in your code are:
You are adding your urls in separate list with static specifier. Instead of this you should add the url variable in your News model directly. And you can directly retrieve the whole News model inside ListView > setOnItemClickListener.
You are creating Bitmap for all your images. It may cause OOM Exception. You should use any Image loading library instead.
I have fixed that all issues and created working code. Please do required changes which you want at your end.
HealthNews.java
public class HealthNews extends AppCompatActivity {
private Context context;
private NewsAdapter mNewsAdapter;
private ArrayList<News> listNews;
private static final String REQUEST_URL = "https://newsapi.org/v2/top-headlines?country=in&category=health&apiKey=3f7d99cdbb004766892bd239a4c099be";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.health_news);
context = this;
ListView list_news = findViewById(R.id.list_news);
listNews = new ArrayList<>();
mNewsAdapter = new NewsAdapter(context, listNews);
list_news.setAdapter(mNewsAdapter);
list_news.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
try {
News selNews = (News) parent.getAdapter().getItem(position);
startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse(selNews.getUrl())));
} catch (Exception e) {
// Missing 'http://' or 'https://' will cause crash
e.printStackTrace();
}
}
});
new NewsAsyncTask().execute(REQUEST_URL);
}
private class NewsAsyncTask extends AsyncTask<String, Void, ArrayList<News>> {
private ProgressDialog p;
#Override
public void onPreExecute() {
super.onPreExecute();
p = new ProgressDialog(context);
p.setMessage("Latest News...");
p.setIndeterminate(false);
p.show();
}
#Override
public ArrayList<News> doInBackground(String... urls) {
return QueryUtils.fetchEarthquakeData(urls[0]);
}
#Override
public void onPostExecute(ArrayList<News> newsList) {
super.onPostExecute(newsList);
listNews.addAll(newsList);
p.hide();
mNewsAdapter.notifyDataSetChanged();
}
}
}
QueryUtils.java
public class QueryUtils {
public static ArrayList<News> fetchEarthquakeData(String apiUrl) {
ArrayList<News> listNews = new ArrayList<>();
try {
URL url = new URL(apiUrl);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setReadTimeout(30000);
conn.setConnectTimeout(60000);
conn.setRequestMethod("GET");
conn.connect();
int responseCode = conn.getResponseCode();
InputStream iStream;
if (responseCode == HttpURLConnection.HTTP_OK)
iStream = conn.getInputStream();
else
iStream = conn.getErrorStream();
BufferedReader br = new BufferedReader(new InputStreamReader(iStream));
StringBuilder response = new StringBuilder();
String line;
while ((line = br.readLine()) != null) {
response.append(line);
}
String jsonResponse = response.toString();
if (TextUtils.isEmpty(jsonResponse))
return null;
JSONObject jsonObject1 = new JSONObject(jsonResponse);
JSONArray baseJSONArray = jsonObject1.getJSONArray("articles");
for (int i = 0; i < baseJSONArray.length(); i++) {
JSONObject jsonObject = baseJSONArray.getJSONObject(i);
JSONObject source = jsonObject.getJSONObject("source");
News news = new News();
news.setArticle(jsonObject.optString("title"));
news.setUrl(jsonObject.optString("url"));
news.setUrlToImage(jsonObject.optString("urlToImage"));
listNews.add(news);
}
} catch (JSONException e) {
e.printStackTrace();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return listNews;
}
}
News.java (Model)
public class News {
private String article;
private String url;
private String urlToImage;
public News() {
this.article = "";
this.url = "";
this.urlToImage = "";
}
public String getArticle() {
return article;
}
public void setArticle(String article) {
this.article = article;
}
public String getUrl() {
return url;
}
public void setUrl(String url) {
this.url = url;
}
public String getUrlToImage() {
return urlToImage;
}
public void setUrlToImage(String urlToImage) {
this.urlToImage = urlToImage;
}
}
NewsAdapter.java (Change your item layout as per your code)
public class NewsAdapter extends BaseAdapter {
private Context context;
private LayoutInflater mInflater;
private List<News> listNews;
public NewsAdapter(Context context, List<News> listNews) {
this.context = context;
this.listNews = listNews;
mInflater = LayoutInflater.from(context);
}
#Override
public int getCount() {
return listNews.size();
}
#Override
public News getItem(int position) {
return listNews.get(position);
}
#Override
public long getItemId(int position) {
return position;
}
private class ViewHolder {
private ImageView item_img_news;
private TextView item_txt_article;
}
#SuppressLint("InflateParams")
#Override
public View getView(final int position, View convertView, ViewGroup parent) {
final ViewHolder holder;
if (convertView == null) {
convertView = mInflater.inflate(R.layout.item_news, null);
holder = new ViewHolder();
holder.item_img_news = convertView.findViewById(R.id.item_img_news);
holder.item_txt_article = convertView.findViewById(R.id.item_txt_article);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
final News news = getItem(position);
holder.item_txt_article.setText(news.getArticle());
Glide.with(context).load(news.getUrlToImage()).into(holder.item_img_news);
return convertView;
}
}
app > build.gradle
implementation 'com.github.bumptech.glide:glide:4.9.0'

JSON returns data in one code and null in other

I have an app that connects to server sends sql request and get JSON answer as JsonArray.
Its Asynktask in seperate class (HTTPRequest.java is my AsyncTask class, Responce.java its my callback interface class) and it works correct.
when I use it in OrderActivity.java like below
#Override //my interface class function
public void onPostExecute(JSONArray Result) {
load(Result);
}
private void load(JSONArray json) {
for(int i=0;i<json.length();i++){
try {
JSONObject jo = json.getJSONObject(i);
Product p = new Product(
jo.getInt("ID"),
jo.getInt("parent"),
jo.getInt("category"),
jo.getString("Item"),
jo.getDouble("Price")
);
products.add(p);
} catch (JSONException e) {
e.printStackTrace();
}
}
it does work and fills product with data, but when I assign to my class variable JSONArray json
JSONArray json = new JSONArray;
.
.
.
#Override
public void onPostExecute(JSONArray Result) {
json = Result;
}
json is null
//HTTPRequest.java
public class HTTPRequest extends AsyncTask<String, Void, Integer> {
private Context context;
private Responce responce;
JSONArray json;
public HTTPRequest(Context context){
this.context = context;
responce = (Responce)context;
}
#Override
protected Integer doInBackground(String... params) {
OutputStream output;
InputStream inputStream = null;
HttpURLConnection connection = null;
String charset = "UTF-8";
Integer result = 0;
try {
URL uri = new URL(params[0]);
connection = (HttpURLConnection) uri.openConnection();
connection.setDoOutput(true);
connection.setRequestProperty("Accept-Charset", charset);
connection.setRequestProperty("Content-Type", "text/plain; charset=" + charset);
output = connection.getOutputStream();
output.write(params[1].getBytes(charset));
output.close();
int statusCode = connection.getResponseCode();
if (statusCode == 200) {
inputStream = new BufferedInputStream(connection.getInputStream());
json = new JSONArray(getJSON(inputStream));
result = 1;
}
} catch (Exception e) {
e.getLocalizedMessage();
}
return result;
}
#Override
protected void onPostExecute(Integer i) {
super.onPostExecute(i);
if(i == 1) {
responce.onPostExecute(json);
} else {
responce.onPostExecute(null);
}
}
private String getJSON(InputStream inputStream) throws IOException, JSONException {
StringBuffer stringBuffer = new StringBuffer();
BufferedReader bufferedReader = new BufferedReader( new InputStreamReader(inputStream));
String line = "";
String result = null;
while((line = bufferedReader.readLine()) != null) {
stringBuffer.append(line.toString());
}
result = stringBuffer.toString();
if(null!=inputStream){
inputStream.close();
}
return result;
}
}
//Responce.java
public interface Responce {
public void onPostExecute(JSONArray Result);
}
//OrderActivity.java
public class OrderActivity extends Activity implements Responce{
ArrayList<Product> products = new ArrayList<Product>();
ProductAdapter productAdapter;
OrderItemAdapter orderItemAdapter;
ListView orderlist;
JSONArray ja;
Button btnBack;
Button btnTakeOrder;
ListView picklist;
HTTPRequest httpRequest;
String url = "http://192.168.3.125:8888/data/";
String query = "select * from vwitems order by category desc";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_order);
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
orderlist =(ListView)findViewById(R.id.orderlist);
orderItemAdapter = new OrderItemAdapter(OrderActivity.this);
btnBack = (Button)findViewById(R.id.btnBack);
btnBack.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
productAdapter.filter(0);
}
});
btnTakeOrder = (Button)findViewById(R.id.btnTakeOrder);
btnTakeOrder.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Integer oid = 0;
Order order = new Order(OrderActivity.this);
oid = order.NewOrder(1, 2, 3);
Toast.makeText(OrderActivity.this," " + order.getCount(), LENGTH_SHORT).show();
}
});
orderlist.setAdapter(orderItemAdapter);
picklist = (ListView) findViewById(R.id.picklist);
picklist.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
int pid = 0;
if (productAdapter.getItem(position).isCategory()) {
pid = productAdapter.getItem(position).getId();
productAdapter.filter(pid);
} else {
OrderItem oi = new OrderItem();
oi.setItemId(productAdapter.getItem(position).getId());
oi.setItem(productAdapter.getItem(position).getItem());
oi.setPrice(productAdapter.getItem(position).getPrice());
search(oi);
}
}
});
httpRequest = new HTTPRequest(this);
httpRequest.execute(url, query);
}
private boolean search(OrderItem oi){
int size = orderItemAdapter.getCount();
int i = 0;
if(size != 0)
for(OrderItem o : orderItemAdapter.getAll()){
if(o.getItemId() == oi.getItemId()){
orderItemAdapter.getItem(i).setQuantity(orderItemAdapter.getItem(i).getQuantity() + 1);
orderItemAdapter.notifyDataSetChanged();
return true;
}
i++;
}
orderItemAdapter.addItem(oi);
orderItemAdapter.notifyDataSetChanged();
return false;
}
private void load(JSONArray json) {
for(int i=0;i<json.length();i++){
try {
JSONObject jo = json.getJSONObject(i);
Product p = new Product(
jo.getInt("ID"),
jo.getInt("parent"),
jo.getInt("category"),
jo.getString("Item"),
jo.getDouble("Price")
);
products.add(p);
} catch (JSONException e) {
e.printStackTrace();
}
}
productAdapter = new ProductAdapter(OrderActivity.this, products);
picklist.setAdapter(productAdapter);
productAdapter.filter(0);
}
#Override
public void onPostExecute(JSONArray Result) {
load(Result);
}
/*
#Override
public void onPostExecute(JSONArray Result) {
json = Result;
}
**/
}
sorry i forgot include this one
//Order.java
public class Order implements Responce{
private Context context;
private JSONArray json = new JSONArray();
private HTTPRequest httpRequest;
private int OrderID;
private Date OrderDate;
private int OrderTable;
private int Waiter;
private byte OrderStatus;
private List<OrderItem> orderItems;
public Order(Context context){
this.context = context;
}
//some code here...
public Integer NewOrder(Integer guests, Integer waiter, Integer ordertable){
String query = "insert into orders(orderdate, guests, waiter, ordertable) VALUES(NOW()," + guests + ", " + waiter + ", " + ordertable + "); SELECT LAST_INSERT_ID() as ID;";
Integer result = 0;
Connect(query);
try {
JSONObject jo = json.getJSONObject(0);
result = jo.getInt("ID");
} catch (JSONException e) {
e.printStackTrace();
}
return result; //here i got 0 if i init result to 0, null or what ever i init my
}
#Override
public void onPostExecute(JSONArray Result) {
json = Result;
}
private void Connect (String query){
httpRequest = new HTTPRequest(context);
httpRequest.execute("http://192.168.3.125:8888/data/", query);
}
}

AsyncTask to fetch global game scores from a server

I am new to android and am completely puzzled by AsyncTasks. I need to create a leaderboard which will pull global leaderboard scores from a server.
I have posted below the two methods that were created in the LeaderboardsFragment which are used to access and display the scores - getGlobalScores and readStream.
I am unsure of how to use these in the AsyncTask - mostly how and what parameters to pass to the AsyncTask - most of the tutorials I have been looking at do not deal with 2D arrays. Any hints would be really appreciated, I am really having trouble understanding the literature surrounding this.
package uk.ni.appidemic.whackamole;
import java.io.BufferedReader;
public class LeaderboardsFragment extends Fragment {
AssetStore AS;
private TextView TopScores;
private String[][] global_scores = new String[10][3];
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_leaderboards, container, false);
//Go and get the asset store from the activity
AS = WhackAMoleActivity.getAssetManager();
TopScores = (TextView) rootView.findViewById(R.id.leaderboards);
// Extract and display the top score text view from the preferences
displayLocalScores();
// this method is used to send a highscore to the server (name and score)
// this method may get pulled out to the gameloop as its the only place it should be used in the final game
// but this can be used for testing purposes atm (Server needs to be on)
// sendScoreGlobal("porter", 1001);
//async Get global scores from the server and display them - new thread
new AsyncOperation().execute();
...................
public void getGlobalScores() {
//gets global score in HTML format to be parsed
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
try {
URL url = new URL("http://62........./high_scores");
HttpURLConnection con = (HttpURLConnection) url.openConnection();
readStream(con.getInputStream());
} catch (Exception e) {
e.printStackTrace();
}
}
/gets the data and stores the global scores in a 2d array
//it then displays to screen
public void readStream(InputStream in) {
BufferedReader reader = null;
try {
StringBuilder htmlIn = new StringBuilder();
StringBuilder globalScoreBuilder = new StringBuilder();
htmlIn.append("");
reader = new BufferedReader(new InputStreamReader(in));
String line = "";
while ((line = reader.readLine()) != null) {
htmlIn.append(line);
}
// String to be scanned to find the pattern.
String html = htmlIn.toString();
String regexPattern = "<td align=\"left\" style=\"padding-left:10px;\">(\\d+?)</td>|<td align=\"right\" style=\"padding-right:10px;\">(\\w+?)</td>";
// Create a Pattern object
Pattern patternObject = Pattern.compile(regexPattern);
// Now create matcher object.
Matcher matcherObject = patternObject.matcher(html);
Log.d(getActivity().getResources().getString(R.string.LOG_TAG), "Trying to find regex matches");
TopScores.append("\n");
int nextFreePointer = 0;
int rowCount = 0;
while (matcherObject.find()) {
if (matcherObject.group(1) != null) {
Log.d(getActivity().getResources().getString(R.string.LOG_TAG), "Regex match : " + matcherObject.group(1));
globalScoreBuilder.append(matcherObject.group(1) + " ");
global_scores[rowCount][nextFreePointer] = matcherObject.group(1);
nextFreePointer++;
}
if (matcherObject.group(2) != null) {
Log.d(getActivity().getResources().getString(R.string.LOG_TAG), "Regex match : " + matcherObject.group(2));
globalScoreBuilder.append(matcherObject.group(2) + " ");
global_scores[rowCount][nextFreePointer] = matcherObject.group(2);
nextFreePointer++;
}
if (nextFreePointer > 2) {
nextFreePointer = 0;
rowCount++;
}
globalScoreBuilder.append("\n");
}
StringBuilder sb = new StringBuilder();
String lineSeparator = System.getProperty("line.separator");
for (String[] row : global_scores) {
sb.append(Arrays.toString(row)).append(lineSeparator);
}
String text = sb.toString();
TopScores.append("Global Top 10 Scores\n");
TopScores.append(text);
} catch (IOException e) {
e.printStackTrace();
} finally {
if (reader != null) {
try {
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
public class AsyncOperation extends AsyncTask<String, Void, Void>{
protected void onPreExecute(){
}//end of onPreExecute
#Override
protected Void doInBackground(Void... values) {
}//doinBackground
protected void onProgressUpdate(Void... values){
}//onProgressUpdate
protected void onPostExecute(Void... result){
}//end of onPostExecute
}//end of AsyncOperation inner class
}//end of Leaderboards class

You should fetch your game score through a WebService class that extentds AsynTask. Below is my class that I am using in order to fetch remote data safely.
CODE:
public class WebServiceRestTask extends AsyncTask<HttpUriRequest, Void, Object> {
private static final String TAG = "WebServiceRestTask";
private AbstractHttpClient mClient;
private WeakReference<WebServiceRestCallback> mCallback;
private int ws_task;
public WebServiceRestTask(int ws_task) {
this(new DefaultHttpClient(), ws_task);
}
public WebServiceRestTask(AbstractHttpClient client, int task_number) {
mClient = client;
this.ws_task = task_number;
}
public interface WebServiceRestCallback {
public void onRequestSuccess(String response);
public void onRequestError(Exception error);
}
public void setResponseCallback(WebServiceRestCallback callback) {
mCallback = new WeakReference<WebServiceRestCallback>(callback);
}
#Override
protected Object doInBackground(HttpUriRequest... params) {
try {
HttpUriRequest request = params[0];
HttpResponse serverResponse = mClient.execute(request);
BasicResponseHandler handler = new BasicResponseHandler();
String response = handler.handleResponse(serverResponse);
return response + ws_task;
} catch (Exception e) {
Log.w(TAG, e);
return e;
}
}
#Override
protected void onPostExecute(Object result) {
if (mCallback != null && mCallback.get() != null) {
if (result instanceof String) {
mCallback.get().onRequestSuccess((String) result);
} else if (result instanceof Exception) {
mCallback.get().onRequestError((Exception) result);
} else {
mCallback.get().onRequestError(
new IOException("Unknown Error Contacting Host"));
}
}
}
}

Not at my workstation but think something like this should work.
public class AsyncOperation extends AsyncTask<String, Void, Void>{
private String[][] global_scores = new String[10][3];
protected void onPreExecute(){
// optionally show loading indicator
TopScores.append("\n");
}//end of onPreExecute
#Override
protected Void doInBackground(Void... values) {
try {
URL url = new URL("http://62........./high_scores");
HttpURLConnection con = (HttpURLConnection) url.openConnection();
readStream(con.getInputStream());
} catch (Exception e) {
e.printStackTrace();
}
}//doinBackground
protected void onProgressUpdate(Void... values){
}//onProgressUpdate
protected void onPostExecute(Void... result){
// optionally hide loading indicator
StringBuilder sb = new StringBuilder();
String lineSeparator = System.getProperty("line.separator");
for (String[] row : global_scores) {
sb.append(Arrays.toString(row)).append(lineSeparator);
}
String text = sb.toString();
TopScores.append("Global Top 10 Scores\n");
TopScores.append(text);
}//end of onPostExecute
private void readStream(InputStream in) {
BufferedReader reader = null;
try {
StringBuilder htmlIn = new StringBuilder();
StringBuilder globalScoreBuilder = new StringBuilder();
htmlIn.append("");
reader = new BufferedReader(new InputStreamReader(in));
String line = "";
while ((line = reader.readLine()) != null) {
htmlIn.append(line);
}
// String to be scanned to find the pattern.
String html = htmlIn.toString();
String regexPattern = "<td align=\"left\" style=\"padding-left:10px;\">(\\d+?)</td>|<td align=\"right\" style=\"padding-right:10px;\">(\\w+?)</td>";
// Create a Pattern object
Pattern patternObject = Pattern.compile(regexPattern);
// Now create matcher object.
Matcher matcherObject = patternObject.matcher(html);
Log.d(getActivity().getResources().getString(R.string.LOG_TAG), "Trying to find regex matches");
int nextFreePointer = 0;
int rowCount = 0;
while (matcherObject.find()) {
if (matcherObject.group(1) != null) {
Log.d(getActivity().getResources().getString(R.string.LOG_TAG), "Regex match : " + matcherObject.group(1));
globalScoreBuilder.append(matcherObject.group(1) + " ");
global_scores[rowCount][nextFreePointer] = matcherObject.group(1);
nextFreePointer++;
}
if (matcherObject.group(2) != null) {
Log.d(getActivity().getResources().getString(R.string.LOG_TAG), "Regex match : " + matcherObject.group(2));
globalScoreBuilder.append(matcherObject.group(2) + " ");
global_scores[rowCount][nextFreePointer] = matcherObject.group(2);
nextFreePointer++;
}
if (nextFreePointer > 2) {
nextFreePointer = 0;
rowCount++;
}
globalScoreBuilder.append("\n");
}
} catch (IOException e) {
e.printStackTrace();
} finally {
if (reader != null) {
try {
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}//end of AsyncOperation inner class

How to show a progress spinner in android, when doInBackground() is being executed

This is my Activity class where i use AsyncTask to get data from a server:
public class UserProfileActivity extends Activity {
private ImageView userImage;
private TextView userName;
private TextView userLocation;
private TextView editInfo;
private TextView chnageImage;
private TextView userScore;
private ListView friendsList;
public ArrayAdapter<String> adapter;
public int score;
public int level;
public String image;
public String fname;
public String lname;
public String city;
public int id;
public String email;
protected Activity activity = this;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.user_profile);
userImage = (ImageView) findViewById(R.id.profileImage);
userName = (TextView) findViewById(R.id.userName_profile);
userLocation = (TextView) findViewById(R.id.userLocation_profile);
editInfo = (TextView) findViewById(R.id.edit_profile);
chnageImage = (TextView) findViewById(R.id.changeImage_profile);
userScore = (TextView) findViewById(R.id.userScore_profile);
friendsList = (ListView) findViewById(R.id.friendsList);
new LongOperation().execute("");
}
private class LongOperation extends AsyncTask<String, Void, String> {
private InputStream is;
private StringBuilder sb;
private String result;
#Override
protected String doInBackground(String... params) {
try {
HttpPost httppost = new HttpPost(
"http://www.xxxxxxxxx.com/mobile/getProfileInfo");
HttpResponse response = SignUpActivity.httpclient
.execute(httppost);
HttpEntity entity = response.getEntity();
is = entity.getContent();
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) {
}
try {
JSONObject jObj = new JSONObject(result);
String status = jObj.getString("status");
score = jObj.getInt("credits");
level = jObj.getInt("level");
image = jObj.getString("image");
fname = jObj.getString("fname");
lname = jObj.getString("lname");
city = jObj.getString("city");
id = jObj.getInt("user_id");
email = jObj.getString("email");
JSONArray friendsJsonArray = jObj.getJSONArray("friends");
int size = friendsJsonArray.length();
ArrayList<String> friendsNames = new ArrayList<String>();
String[] friendsIds = new String[size];
for (int i = 0; i < size; i++) {
friendsNames.add(friendsJsonArray.getJSONObject(i)
.getString("name"));
}
adapter = new ArrayAdapter<String>(getApplicationContext(),
R.layout.simple_listview_item, friendsNames);
} catch (Exception e) {
}
} catch (Exception e) {
}
return "Executed";
}
#Override
protected void onPostExecute(String result) {
friendsList.setAdapter(adapter);
userScore.setText(score + " points" + " level " + level);
userName.setText(fname + " " + lname);
userLocation.setText(city);
Bitmap bitmap = null;
try {
bitmap = BitmapFactory
.decodeStream((InputStream) new URL(image).getContent());
} catch (MalformedURLException e1) {
e1.printStackTrace();
} catch (IOException e2) {
e2.printStackTrace();
}
userImage.setImageBitmap(bitmap);
}
#Override
protected void onPreExecute() {
}
#Override
protected void onProgressUpdate(Void... values) {
}
}
}
when this activity is loaded it shows all the default values and images and then changes when background code execution is competed(as excepted), but this takes 2-3 secs for which user will be seeing default values, which i dont want to. So how can i keep a spinner like this:
for 2-3 secs and then when the spinner disappears the activity must show the actual values.
Thank you

Refer the below code
private class FetchRSSFeeds extends AsyncTask<String, Void, Boolean> {
private ProgressDialog dialog = new ProgressDialog(HomeActivity.this);
/** progress dialog to show user that the backup is processing. */
/** application context. */
#Override
protected void onPreExecute() {
this.dialog.setMessage("Please wait");
this.dialog.show();
}
#Override
protected Boolean doInBackground(final String... args) {
try {
Utilities.arrayRSS = objRSSFeed
.FetchRSSFeeds(Constants.Feed_URL);
return true;
} catch (Exception e) {
Log.e("tag", "error", e);
return false;
}
}
#Override
protected void onPostExecute(final Boolean success) {
if (dialog.isShowing()) {
dialog.dismiss();
}
// Setting data to list adapter
setListData();
}

Do This:-
Declare the ProgressDialog at the Top.
ProgressDialog pd;
Start it in onPreExecute Method of Async Task.
pd=ProgressDialog.show(ActivityName.this,"","Please Wait",false);
Stop it in the onPostExecute Method.
pd.dismiss();

In onCreate method call some like below
mdialog=new Dialog(this);
new LongOperation().execute("");
Then override onPostExecute of AyncTask
#Override
protected void onPostExecute() {
runOnUiThread(new Runnable() {
#Override
public void run() {
// TODO Auto-generated method stub
mdialog.dismiss();
}
});
}

Develop Reference

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AsyncTask to fetch global game scores from a server

How to show a progress spinner in android, when doInBackground() is being executed

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