Android Async Task Freezes UI Completely

Android Async Task Freezes UI Completely - android

I have an Async task that loads information from the server and displays data on the UI. Suddenly the async task downloads the data and formats the JSON data fine but it would freeze the UI completely.
Here is the base download class
public class GetRawData {
private static String LOG_TAG = GetRawData.class.getSimpleName();
private String mRawURL;
private List<NameValuePair> mRawParams = null;
private String mRawData;
private DownloadStatus mDownloadStatus;
public GetRawData(String mRawURL) {
this.mRawURL = mRawURL;
this.mRawParams = null;
this.mDownloadStatus = DownloadStatus.IDLE;
}
public String getRawData() {
return mRawData;
}
public void setRawURL(String mRawURL) {
this.mRawURL = mRawURL;
}
public List<NameValuePair> getRawParams() {
return mRawParams;
}
public void setRawParams(List<NameValuePair> mParams) {
this.mRawParams = mParams;
}
public DownloadStatus getDownloadStatus() {
return mDownloadStatus;
}
public void reset() {
this.mRawURL = null;
this.mRawData = null;
this.mDownloadStatus = DownloadStatus.IDLE;
}
public void execute() {
this.mDownloadStatus = DownloadStatus.PROCESSING;
DownloadRawData mDownloadRawData = new DownloadRawData();
mDownloadRawData.execute(mRawURL);
}
public class DownloadRawData extends AsyncTask<String, Void, String> {
#Override
protected String doInBackground(String... params) {
// Create URL and Reader instances.
HttpURLConnection urlConnection = null;
BufferedReader reader = null;
//If no parameter has been provided, return null.
if (params == null)
return null;
try {
// Get URL entered by the user.
URL mURL = new URL(params[0]);
urlConnection = (HttpURLConnection) mURL.openConnection();
urlConnection.setDoOutput(true);
urlConnection.setRequestMethod("POST");
urlConnection.setUseCaches(false);
urlConnection.setConnectTimeout(10000);
urlConnection.setReadTimeout(10000);
urlConnection.setRequestProperty("Content-Type","application/json");
//urlConnection.setRequestProperty("Host", "android.schoolportal.gr");
urlConnection.connect();
// validate and add parameters if available.
if (mRawParams != null && mRawParams.size()>0){
JSONObject jsonParam = new JSONObject();
for (NameValuePair pair : mRawParams) {
jsonParam.put(pair.getName().toString(), pair.getValue().toString());
}
String jsonparams = jsonParam.toString();
// Send POST output.
DataOutputStream printout;
printout = new DataOutputStream(urlConnection.getOutputStream());
printout.writeBytes(jsonparams);
printout.flush();
printout.close();
}
int HttpResult =urlConnection.getResponseCode();
StringBuffer buffer = new StringBuffer();
if(HttpResult ==HttpURLConnection.HTTP_OK){
InputStream inputStream = urlConnection.getInputStream();
if (inputStream == null) {
return null;
}
reader = new BufferedReader(new InputStreamReader(inputStream));
String line;
while ((line = reader.readLine()) != null) {
buffer.append(line + "\n");
}
System.out.println(""+buffer.toString());
}else{
InputStream errorStream = urlConnection.getErrorStream();
if (errorStream == null) {
return null;
}
reader = new BufferedReader(new InputStreamReader(errorStream));
String line;
while ((line = reader.readLine()) != null) {
buffer.append(line + "\n");
}
System.out.println(urlConnection.getResponseMessage());
}
return buffer.toString();
} catch (IOException e) {
Log.d("IOException", e.toString());
return null;
} catch (JSONException j) {
Log.d("JSONException", j.toString());
return null;
} finally {
if (urlConnection != null) {
urlConnection.disconnect();
}
if (reader != null) {
try {
reader.close();
} catch (IOException e) {
Log.d("IOException", "unable to close the reader");
}
}
}
}
#Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
mRawData = result;
//Log.d("onPostExecute", result);
if (mRawData == null) {
if (mRawURL == null) {
mDownloadStatus = DownloadStatus.NOT_INITIALIZED;
} else {
mDownloadStatus = DownloadStatus.FAILED_OR_EMPTY;
}
} else {
mDownloadStatus = DownloadStatus.PROCESSED;
}
}
private String getQuery(List<NameValuePair> params) throws UnsupportedEncodingException {
StringBuilder result = new StringBuilder();
boolean first = true;
for (NameValuePair pair : params) {
if (first)
first = false;
else
result.append("&");
result.append(URLEncoder.encode(pair.getName(), "UTF-8"));
result.append("=");
result.append(URLEncoder.encode(pair.getValue(), "UTF-8"));
}
return result.toString();
}
}
}
enum DownloadStatus {
IDLE,
PROCESSING,
NOT_INITIALIZED,
FAILED_OR_EMPTY,
PROCESSED
}
Here is the specific data formatting class the extends above class
public class GetJobCardJsonData extends GetRawData {
private static String LOG_TAG = GetAuthenticationJsonData.class.getSimpleName();
private static String JOBCARD_SERVICE_URL = "http://www.appservice.com/appservice/jobcardinfoservice.asmx/GetJobCardInfo";
private List<JobCard> mJobCardList;
private CarcalDownloadListener mListener;
public GetJobCardJsonData(String CurrentDate, int DealershipID) {
super(null);
List<NameValuePair> mParams = new ArrayList<NameValuePair>();
mParams.add(new BasicNameValuePair("JobCardDate", CurrentDate));
mParams.add(new BasicNameValuePair("DealershipID", String.valueOf(DealershipID)));
this.setRawParams(mParams);
}
public List<JobCard> getJobCardList() {
return mJobCardList;
}
public void getjobcards() {
super.setRawURL(JOBCARD_SERVICE_URL);
DownloadJobCardJsonData mDownloadJobCardJsonData = new DownloadJobCardJsonData();
mDownloadJobCardJsonData.execute(JOBCARD_SERVICE_URL);
}
public void setOnCarcalDownloadListener(CarcalDownloadListener onCarcalDownloadListener) {
this.mListener = onCarcalDownloadListener;
}
private void processResult() {
if (getDownloadStatus() != DownloadStatus.PROCESSED) {
Log.e(LOG_TAG, "Error Downloading the raw file.");
return;
}
if (mJobCardList == null){
mJobCardList = new ArrayList<JobCard>();
}
final String JOBCARD_JOBCARDID = "JobCardID";
final String JOBCARD_GETSTOCKNUMBER_WITH_DELIVERYTIME = "StockNumberWithDeliveryTime";
final String JOBCARD_CUSTOMERNAME = "CustomerName";
final String JOBCARD_MODELNUMBER = "ModelNumber";
final String JOBCARD_COLOR = "Color";
final String JOBCARD_SALEEXECUTIVE = "SaleExecutive";
final String JOBCARD_ORDERSTATUS = "OrderStatus";
final String JOBCARD_SHOWROOMSTATUS = "ShowRoomStatus";
try {
JSONArray jsonArray = new JSONArray(getRawData());
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject jobcarditem = jsonArray.optJSONObject(i);
Long JOBCARDID = jobcarditem.getLong(JOBCARD_JOBCARDID);
String STOCKWITHDELIVERY = jobcarditem.getString(JOBCARD_GETSTOCKNUMBER_WITH_DELIVERYTIME);
String CUSTOMERNAME = jobcarditem.getString(JOBCARD_CUSTOMERNAME);
String MODELNUMBER = jobcarditem.getString(JOBCARD_MODELNUMBER);
String COLOR = jobcarditem.getString(JOBCARD_COLOR);
String SALEEXECUTIVE = jobcarditem.getString(JOBCARD_SALEEXECUTIVE);
int ORDERSTATUS = jobcarditem.getInt(JOBCARD_ORDERSTATUS);
int SHOWROOMSTATUS = jobcarditem.getInt(JOBCARD_SHOWROOMSTATUS);
JobCard mJobCard = new JobCard(JOBCARDID, STOCKWITHDELIVERY, CUSTOMERNAME, MODELNUMBER, COLOR, SALEEXECUTIVE, ORDERSTATUS, SHOWROOMSTATUS);
mJobCardList.add(mJobCard);
}
} catch (JSONException jsone) {
jsone.printStackTrace();
Log.e(LOG_TAG, "Error processing json data.");
}
}
public class DownloadJobCardJsonData extends DownloadRawData {
#Override
protected String doInBackground(String... params) {
return super.doInBackground(params[0]);
}
#Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
processResult();
mListener.OnDownloadCompleted();
}
}
}
Here is the code that is called on the activity
private JobCardRecyclerViewAdapter mJobCardRecyclerViewAdapter;
private GetJobCardJsonData mGetJobCardJsonData;
SessionManager session;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_job_card_calender);
activateToolbarWithHomeEnabled();
String formattedDate="";
if (session.getCurrentDate() == ""){
Calendar c = Calendar.getInstance();
SimpleDateFormat df = new SimpleDateFormat("MM/dd/yyyy");
formattedDate = df.format(c.getTime());
currentDateTextView.setText(formattedDate);
}else {
formattedDate = session.getCurrentDate();
currentDateTextView.setText(formattedDate);
}
// Fetch data for current date.
mGetJobCardJsonData = new GetJobCardJsonData(formattedDate, session.getDealershipID());
mGetJobCardJsonData.getjobcards();
mGetJobCardJsonData.setOnCarcalDownloadListener(new CarcalDownloadListener() {
#Override
public void OnDownloadCompleted() {
List<JobCard> mJobCards = mGetJobCardJsonData.getJobCardList();
mJobCardRecyclerViewAdapter = new JobCardRecyclerViewAdapter(mJobCards, JobCardCalenderActivity.this);
mRecyclerView.setAdapter(mJobCardRecyclerViewAdapter);
}
});
}
Can anyone help on what i am doing wrong that is freezing the UI. It was working fine before and has started to freeze the UI suddenly.

I was able to fix the issue, the problem was not with Async task but with the layout. I accidently wrapped the recycler view with scroll view. which was causing the UI to freeze. Looks weird that a scroll view caused the whole UI thread to freeze. but here is my solution
<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent">
<view
android:id="#+id/jobCardRecyclerView"
class="android.support.v7.widget.RecyclerView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="#id/jobCardHeader"
android:scrollbars="vertical"></view>
</ScrollView>
Changed it to
<view
android:id="#+id/jobCardRecyclerView"
class="android.support.v7.widget.RecyclerView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="#id/jobCardHeader"
android:scrollbars="vertical"></view>
hope it will be helpful for others facing same problem.

Related

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'

Android, Handling multiple URL for parsing

I am making a simple news reader app. The news need to be shown in one RecyclerView, like a list of news. The problem is that there are a multiple URLs from whom i extract data and i know only how to parse one but dont know how to handle more of them. Here is my code:
public class NewsActivity extends AppCompatActivity {
public static final String LOG_TAG = NewsActivity.class.getSimpleName();
public static final String newsUrl1 = "http://tests.intellex.rs/api/v1/news/list?page=1";
public static final String newsUrl2 = "http://tests.intellex.rs/api/v1/news/list?page=2";
public static final String newsUrl3 = "http://tests.intellex.rs/api/v1/news/list?page=3";
public static final String newsUrl4 = "http://tests.intellex.rs/api/v1/news/list?page=4";
private NewsAdapter adapter;
private RecyclerView recyclerView;
private ArrayList<NewsModel> newsArray;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.a_news_recycler_view__);
newsArray = new ArrayList<>();
adapter = new NewsAdapter(this, newsArray);
RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(getApplicationContext());
recyclerView = (RecyclerView) findViewById(R.id.newsRecyclerView);
recyclerView.setLayoutManager(mLayoutManager);
recyclerView.addItemDecoration(new SimpleDividerItemDecoration(getApplicationContext()));
recyclerView.setAdapter(adapter);
recyclerView.setHasFixedSize(true);
NewsAsyncTask task = new NewsAsyncTask();
task.execute();
}
private class NewsAsyncTask extends AsyncTask<URL, Void, ArrayList<NewsModel>> {
#Override
protected ArrayList<NewsModel> doInBackground(URL... urls) {
URL url = createUrl(newsUrl1);
String jsonResponse = "";
try {
jsonResponse = makeHttpRequest(url);
} catch (IOException e) {
e.printStackTrace();
}
return extractFeatureFromJson(jsonResponse);
}
#Override
protected void onPostExecute(ArrayList<NewsModel> news) {
if (news == null) {
return;
}
adapter.addAll(news);
}
private URL createUrl(String stringUrl) {
URL url = null;
try {
url = new URL(stringUrl);
} 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();
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 JSON results.", e);
} finally {
if (urlConnection != null) {
urlConnection.disconnect();
}
if (inputStream != null) {
// function must handle java.io.IOException here
inputStream.close();
}
}
return jsonResponse;
}
private 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();
}
private ArrayList<NewsModel> extractFeatureFromJson(String newsJson) {
if (TextUtils.isEmpty(newsJson)) {
return null;
}
ArrayList<NewsModel> news_information = new ArrayList<>();
try {
JSONObject baseJsonResponse = new JSONObject(newsJson);
JSONArray newsArray = baseJsonResponse.getJSONArray("list");
for (int i = 0; i < newsArray.length(); i++) {
JSONObject news = newsArray.getJSONObject(i);
try {
news = newsArray.getJSONObject(i);
String newsImage = news.getString("image");
String newsTitle = news.getString("title");
String newsPublished = news.getString("published");
String newsAuthor = news.getString("author");
String newsID = news.getString("id");
NewsModel newsModel = new NewsModel(newsImage, newsTitle, newsPublished, newsAuthor, newsID);
news_information.add(newsModel);
} catch (JSONException e) {
e.printStackTrace();
}
}
} catch (JSONException e) {
e.printStackTrace();
}
return news_information;
}
}
}
Any help would be appreciated. Thanks in advance.

Why don't you use "links" as array ?
In case you will use an array:
JSONObject jsonObject = new JSONObject();
JSONArray keys = jsonObject.getJSONArray("links");
int length = keys.length();
for (int i = 0; i < length; i++) {
new ReadJSON().execute(keys.getString(i));
}
Anyway, you take all the keys and go one after the other, and then query each
EDIT:
JSONObject jsonObject = new JSONObject(/*Your links json*/);
JSONObject links = jsonObject.get("links");
Iterator<String> keys = links.keys();
while (keys.hasNext()) {
new ReadJSON().execute(links.getString(keys.next()));
}

ArrayAdapter is null even after getting a string array as a parameter

I'm working on the Sunshine app in the Developing Android App course by Udacity. Currently stuck in lesson 2. I've listed down the MainActivity.java that contains a listview that is populated by a network call in the AsyncTask as an inner class in the MainActivity.java. But the application crashes, due to a null pointer exception, as the array adapter is null. I've tried debugging, and the weekForecast (i.e., the ArrayList that stores the parsed data, and is a parameter to the creation of the ArrayAdapter) does have valid parsed data. Thanks for the help in advance.
public class MainActivity extends AppCompatActivity {
ListView listView;
ArrayAdapter<String> arrayAdapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView=(ListView)findViewById(R.id.listview_forecast);
GettingWeatherFromNetwork gettingWeatherFromNetwork = new GettingWeatherFromNetwork();
gettingWeatherFromNetwork.execute("94043");
listView.setAdapter(arrayAdapter);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.main,menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
switch(id) {
case R.id.action_settings : return true;
case R.id.action_refresh : GettingWeatherFromNetwork gettingWeatherFromNetwork = new GettingWeatherFromNetwork();
gettingWeatherFromNetwork.execute("94043");
return true;
}
return super.onOptionsItemSelected(item);
}
public class GettingWeatherFromNetwork extends AsyncTask<String, Void, String[]> {
private final String LOG_TAG = GettingWeatherFromNetwork.class.getSimpleName();
//Removed API KEY. But it is a part of the main code I'm running.
private final String API_KEY = " ";
#Override
protected String[] doInBackground(String... params) {
HttpURLConnection urlConnection = null;
BufferedReader reader = null;
String forecastJsonStr = null;
String format = "json";
String units = "metric";
int noOfDays = 7;
try {
final String BASE_URL = "http://api.openweathermap.org/data/2.5/forecast/daily?";
final String QUERY_PARAM = "q";
final String MODE_PARAM = "mode";
final String UNITS_PARAM = "units";
final String COUNT_PARAM = "cnt";
final String KEY_PARAM = "appid";
Uri builtURI = Uri.parse(BASE_URL).buildUpon()
.appendQueryParameter(QUERY_PARAM,params[0])
.appendQueryParameter(MODE_PARAM,format)
.appendQueryParameter(UNITS_PARAM,units)
.appendQueryParameter(COUNT_PARAM, String.valueOf(noOfDays))
.appendQueryParameter(KEY_PARAM,API_KEY)
.build();
String Url = builtURI.toString();
URL url = new URL(Url);
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.connect();
InputStream inputStream = urlConnection.getInputStream();
StringBuffer buffer = new StringBuffer();
if (inputStream == null) {
return null;
}
reader = new BufferedReader(new InputStreamReader(inputStream));
String line;
while ((line = reader.readLine()) != null) {
buffer.append(line + "\n");
}
if (buffer.length() == 0) {
return null;
}
forecastJsonStr = buffer.toString();
} catch (IOException e) {
Log.e(LOG_TAG, String.valueOf(e));
return null;
} finally{
if (urlConnection != null) {
urlConnection.disconnect();
}
if (reader != null) {
try {
reader.close();
} catch (final IOException e) {
Log.e(LOG_TAG, String.valueOf(e));
}
}
}
String [] weatherForecast = new String[0];
WeatherParser weatherParser = new WeatherParser();
try {
weatherForecast = weatherParser.getWeatherDataFromJson(forecastJsonStr,7);
} catch (JSONException e) {
e.printStackTrace();
}
return weatherForecast;
}
#Override
protected void onPostExecute(String[] s) {
List<String> weekForecast = new ArrayList<String>(Arrays.asList(s));
arrayAdapter = new ArrayAdapter<String>(getApplicationContext(),R.layout.list_item_forecast,R.id.list_item_forecast_textview,weekForecast);
}
}
}

Try removing the line
listView.setAdapter(arrayAdapter);
from onCreate method and add it in onPostExecute() method of AsyncTask, after initialising the arrayAdapter.
#Override
protected void onPostExecute(String[] s) {
List<String> weekForecast = new ArrayList<String>(Arrays.asList(s));
arrayAdapter = new ArrayAdapter<String>(getApplicationContext(),R.layout.list_item_forecast,R.id.list_item_forecast_textview,weekForecast);
//set adapter set to listview after initialzing it.
listView.setAdapter(arrayAdapter);
}

Imageview not showing unless rotate or resume

I am working on my movie project which fetch movie poster from URL, and then putting them into a gridview. I use asynctask to fetch JSON and the parse the url within the json file. However, when I launch my app, the grid is all empty and doing nothing until I rotate my screen or resume my app. Once I rotate my screen or resume my app. It shows all picture. I remove my api key on my code here.
public class FetchMovieTask extends AsyncTask<Void, Void, ArrayList<String>> {
private final String LOG_TAG = FetchMovieTask.class.getSimpleName();
#Override
protected ArrayList<String> doInBackground(Void... params) {
String api_key = "";
HttpURLConnection urlConnection = null;
BufferedReader reader = null;
String movieJsonStr = null;
try {
Uri.Builder builder = new Uri.Builder();
builder.scheme("http")
.authority("api.themoviedb.org")
.appendPath("3")
.appendPath("discover")
.appendPath("movie")
.appendQueryParameter("api_key", api_key);
String myUrl = builder.build().toString();
URL Url = new URL(myUrl);
Log.v(LOG_TAG, myUrl);
// Create the request to OpenWeatherMap, and open the connection
urlConnection = (HttpURLConnection) Url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.connect();
// Read the input stream into a String
InputStream inputStream = urlConnection.getInputStream();
StringBuffer buffer = new StringBuffer();
if (inputStream == null) {
// Nothing to do.
movieJsonStr = null;
}
reader = new BufferedReader(new InputStreamReader(inputStream));
String line;
while ((line = reader.readLine()) != null) {
// Since it's JSON, adding a newline isn't necessary (it won't affect parsing)
// But it does make debugging a *lot* easier if you print out the completed
// buffer for debugging.
buffer.append(line + "\n");
}
if (buffer.length() == 0) {
// Stream was empty. No point in parsing.
movieJsonStr = null;
}
movieJsonStr = buffer.toString();
Log.v("KPN", movieJsonStr);
} catch (IOException e) {
Log.e(LOG_TAG, "Error ", e);
// If the code didn't successfully get the weather data, there's no point in attempting
// to parse it.
movieJsonStr = null;
return null;
} finally {
if (urlConnection != null) {
urlConnection.disconnect();
}
if (reader != null) {
try {
reader.close();
} catch (final IOException e) {
Log.e(LOG_TAG, "Error closing stream", e);
}
}
}
try {
MovieURL = getPosterUrlFromJson(movieJsonStr);
} catch (JSONException e) {
Log.e(LOG_TAG, e.getMessage(), e);
e.printStackTrace();
}
return null;
}
}
private ArrayList<String> getPosterUrlFromJson(String forcastMovieStr)
throws JSONException {
final String OWM_PosterUrl = "poster_path";
final String OWM_releaseDate = "release_date";
final String OWM_overview = "overview";
final String OWM_vote_average = "vote_average";
final String OWM_original_title = "original_title";
final String OWM_results = "results";
JSONObject movieJson = new JSONObject(forcastMovieStr);
JSONArray movieArray = movieJson.getJSONArray(OWM_results);
ArrayList<String> resultStrs = new ArrayList<>();
String posterurl = "http://image.tmdb.org/t/p/w185/";
for (int i = 0; i < movieArray.length(); i++) {
// For now, using the format "Day, description, hi/low"
String title;
String overview;
String poster;
// Get the JSON object for movie poster
JSONObject moveposter = movieArray.getJSONObject(i);
poster = moveposter.getString(OWM_PosterUrl);
resultStrs.add(i,posterurl + poster);
}
return resultStrs;
}
protected void onPostExecute(ArrayList<String> strings) {
MovieURL.clear();
for (String s : strings) {
MovieURL.add(s);
}
}
Main:
public class MainActivity extends AppCompatActivity {
public static ArrayList<String> MovieURL = new ArrayList();
public static ImageListAdapter mImageListAdapter;
public GridView gridview;
#Override
protected void onStart() {
super.onStart();
new FetchMovieTask().execute();
mImageListAdapter = new ImageListAdapter(this,MovieURL);
gridview.setAdapter(mImageListAdapter);
gridview.invalidateViews();
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
gridview = (GridView) findViewById(R.id.gridview);
}
private void updateMovieURL(){
new FetchMovieTask().execute();
gridview.invalidateViews();
}
ImagelistAdapter class
public class ImageListAdapter extends ArrayAdapter {
private Context context;
private LayoutInflater inflater;
private ArrayList<String> imageUrls;
public ImageListAdapter(Context context, ArrayList <String> imageUrls) {
super(context, R.layout.image_view, imageUrls);
this.context = context;
this.imageUrls = imageUrls;
inflater = LayoutInflater.from(context);
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
if (null == convertView) {
convertView = inflater.inflate(R.layout.image_view, parent, false);
}
Picasso.with(context).load(imageUrls.get(position))
.placeholder(R.drawable.loading)
.into((ImageView) convertView);
return convertView;
}
}
THanks guys

In postExecute do this:
protected void onPostExecute(ArrayList<String> strings) {
MovieURL.clear();
for (String s : strings) {
MovieURL.add(s);
}
mImageListAdapter.notifyDataSetChanged();
}

I found my problem on the asynctask, I didnt override the onPostExecute method. After I override my onPostExecute, I initial my grid view
#Override
protected void onPostExecute(ArrayList<String> strings) {
super.onPostExecute(strings);
mImageListAdapter = new ImageListAdapter(MainActivity.this, MovieURL);
gridview.setAdapter(mImageListAdapter);
}

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

Develop Reference

The Android operating system is a mobile operating system that was developed by Google (GOOGL?) to be primarily used for touchscreen devices, cell phones, and tablets.

Android Async Task Freezes UI Completely - android

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ArrayAdapter is null even after getting a string array as a parameter

Imageview not showing unless rotate or resume

AsyncTask to fetch global game scores from a server

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