I'm using recyclerView in my app in which I'm calculating the route distance between the cities in other thread than UI thread. Now I want to refresh the recyclerView's distance field only whenever the distance is calculated.
TIA
public class DashboardAdapter extends RecyclerView.Adapter<DashboardAdapter.ListItemViewHolder> {
private List<DashBoardData> dashBoardData;
private Context context;
public DashboardAdapter(List<DashBoardData> dashBoardData, Context context) {
if (dashBoardData == null) {
throw new IllegalArgumentException("Data must not be null");
}
this.dashBoardData = dashBoardData;
this.context = context;
}
#NonNull
#Override
public ListItemViewHolder onCreateViewHolder(#NonNull ViewGroup viewGroup, int i) {
View itemView = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.item_layout, viewGroup, false);
return new ListItemViewHolder(itemView);
}
#Override
public void onBindViewHolder(#NonNull ListItemViewHolder holder, int position) {
holder.tvSource.setText(dashBoardData.get(position).getSource());
holder.tvDestination.setText(dashBoardData.get(position).getDestination());
getDistance(context,
dashBoardData.get(position).getStartLocation(),
dashBoardData.get(position).getEndLocation());
holder.tvDistance.setText("");
}
#Override
public int getItemCount() {
return dashBoardData.size();
}
public final static class ListItemViewHolder extends RecyclerView.ViewHolder {
TextView tvSource, tvDestination, tvDistance;
public ListItemViewHolder(View itemView) {
super(itemView);
tvSource = (TextView) itemView.findViewById(R.id.tv_from_source);
tvDestination = (TextView) itemView.findViewById(R.id.tv_to_destination);
tvDistance = itemView.findViewById(R.id.tv_distance);
}
}
public static void getDistance(Context context, String srcLocation, String destLocation) {
String url = getDirectionsUrl(context, srcLocation, destLocation);
DownloadTask downloadTask = new DownloadTask();
downloadTask.execute(url);
}
public static class DownloadTask extends AsyncTask<String, Void, String> {
// Downloading data in non-ui thread
#Override
protected String doInBackground(String... url) {
String data = "";
try {
// Fetching the data from web service
String urlEncoded = (url[0]).replaceAll(" ", "");
data = downloadUrl(urlEncoded);
} catch (Exception e) {
Log.d("Background Task", e.toString());
}
return data;
}
// Executes in UI thread, after the execution of
// doInBackground()
#Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
ParserTask parserTask = new ParserTask();
// Invokes the thread for parsing the JSON data
parserTask.execute(result);
}
}
private static String downloadUrl(String strUrl) throws IOException {
String data = "";
InputStream iStream = null;
HttpURLConnection urlConnection = null;
try {
URL url = new URL(strUrl);
urlConnection = (HttpURLConnection) url.openConnection();
// Connecting to url
urlConnection.connect();
// Reading data from url
iStream = urlConnection.getInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(iStream));
StringBuffer sb = new StringBuffer();
String line = "";
while ((line = br.readLine()) != null) {
sb.append(line);
}
data = sb.toString();
br.close();
} catch (Exception e) {
Log.d("Exception downloading url", e.toString());
} finally {
if (iStream != null) {
iStream.close();
}
if (urlConnection != null) {
urlConnection.disconnect();
}
}
return data;
}
private static class ParserTask extends AsyncTask<String, Integer, String> {
#Override
protected String doInBackground(String... jsonData) {
JSONObject jObject;
String distance = "0 Mt";
try {
jObject = new JSONObject(jsonData[0]);
JSONArray jRoutes = null;
JSONArray jLegs = null;
jRoutes = jObject.getJSONArray("routes");
for (int i = 0; i < jRoutes.length(); i++) {
jLegs = ((JSONObject) jRoutes.get(i)).getJSONArray("legs");
for (int j = 0; j < jLegs.length(); j++) {
distance = (String) ((JSONObject)((JSONObject) jLegs.get(j)).get("distance")).get("text");
}
}
} catch (Exception e) {
e.printStackTrace();
}
return distance;
}
#Override
protected void onPostExecute(String result) {
//update ui
}
}
}
this is my adapter and I'm passing a dashboard list to this. After parsing the json data for distance I want to notify the distance field in onPostExecute() method.
The easiest way of doing that is once you are done updating all your data you call notify dataset changed on your adapter something like this:
//Some Code
mAdapter.notifyDataSetChanged();
Where mAdapter is the reference for your RecyclerView Adapter.
Related
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'
I am have sql DB and I am trying to display queried values in a listView. I created a custom adapter for the listView. problem is
I am not able to see any data displayed on my listView.
code of main
public class _songs_playlist extends AppCompatActivity {
ArrayList<songsarray> listofsoongs = new ArrayList<songsarray>();
private static int SPLASH_TIME_OUT=2000;
AlertDialog alertDialog;
private boolean loggedIn = false;
String type;
String result;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity__songs_playlist);
new JSONParse().execute();
MyCustomAdapterSongs itemsAdapter = new MyCustomAdapterSongs(this, listofsoongs);
ListView listView = (ListView) findViewById(R.id.listView1);
listView.setAdapter(itemsAdapter);
itemsAdapter.notifyDataSetChanged();
}
private class JSONParse extends AsyncTask<String, String, JSONObject> {
private ProgressDialog pDialog;
#Override
protected void onPreExecute() {
super.onPreExecute();
alertDialog=new AlertDialog.Builder(_songs_playlist.this).create();
alertDialog.setTitle("Upadting Data");
pDialog = new ProgressDialog(_songs_playlist.this);
pDialog.setMessage("Getting Data ...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}
#Override
protected JSONObject doInBackground(String... args) {
HTTPHandler sh = new HTTPHandler();
String login_URL = "http://2f179dfb.ngrok.io/getsong.php";
try {
//Fetching the boolean value form sharedpreferences
URL url = new URL(login_URL);
HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
httpURLConnection.setRequestMethod("POST");
httpURLConnection.setDoOutput(true);
httpURLConnection.setDoInput(true);
InputStream inputStream = httpURLConnection.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream, "iso-8859-1"));
result = "";
String line = "";
while ((line = bufferedReader.readLine()) != null) {
result += line;
}
bufferedReader.close();
inputStream.close();
httpURLConnection.disconnect();
Log.e("RESULT", result);
JSONObject jsonObject = new JSONObject(result);
JSONArray result1 = jsonObject.getJSONArray("result");
for (int i = 0; i < result1.length(); i++) {
JSONObject c = result1.getJSONObject(i);
String id = c.getString("songID");
String names = c.getString("songName");
String ss = c.getString("singerName");
listofsoongs.add(new songsarray(ss,id,names));
}
return jsonObject;
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(JSONObject json) {
pDialog.dismiss();
if(true)
{
}
else
{
}
}
}
}
code of custom array adapter
public class MyCustomAdapterSongs extends ArrayAdapter<songsarray> {
Context context;
ArrayList<songsarray> items;
public MyCustomAdapterSongs(Activity context, ArrayList<songsarray> songsarrays) {
super(context, 0, songsarrays);
this.context=context;
this.items=songsarrays;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
View listItemView = convertView;
if (listItemView == null) {
listItemView = LayoutInflater.from(getContext()).inflate(
R.layout.itemlist, parent, false);
}
TextView nameTextView = (TextView) listItemView.findViewById(R.id.textView1);
nameTextView.setText(currentAndroidFlavor.getSingername());
Log.e("hhhh", nameTextView.getText().toString());
TextView numberTextView = (TextView) listItemView.findViewById(R.id.textView2);
numberTextView.setText(currentAndroidFlavor.getSongname());
Log.e("jjjj", numberTextView.getText().toString());
CheckBox ch=(CheckBox)listItemView.findViewById(R.id.checkBox1);
ch.setSelected(currentAndroidFlavor.isSelected());
return listItemView;
}
#Override
public int getCount() {
if(items == null)
return 0;
return items.size();
}
#Override
public songsarray getItem(int i) {
return items.get(i);
}
}
Call itemsAdapter.notifyDataSetChanged() within onPostExecute.
Your list is empty until the AsyncTask finishes there.
You'll have to make the adapter a member variable of the Activity class
As in your code I can see you are updating the list in doInBackground but you are not notifying the adapter for the changes.
In onPostExecute method you need to call itemsAdapter.notifyDataSetChanged() and make sure it you are not calling it inside doInBackground as in background thread you can't to UI related work.
Check the EDITS in this code snippet
`
public class _songs_playlist extends AppCompatActivity {
ArrayList<songsarray> listofsoongs = new ArrayList<songsarray>();
private static int SPLASH_TIME_OUT=2000;
AlertDialog alertDialog;
private boolean loggedIn = false;
String type;
String result;
//EDIT 1: Make these member variables
MyCustomAdapterSongs itemsAdapter;
ListView listView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity__songs_playlist);
//EDIT 2: get references your views before AsyncTask
listView = (ListView) findViewById(R.id.listView1);
new JSONParse().execute();
}
private class JSONParse extends AsyncTask<String, String, JSONObject> {
private ProgressDialog pDialog;
#Override
protected void onPreExecute() {
super.onPreExecute();
alertDialog=new AlertDialog.Builder(_songs_playlist.this).create();
alertDialog.setTitle("Upadting Data");
pDialog = new ProgressDialog(_songs_playlist.this);
pDialog.setMessage("Getting Data ...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}
#Override
protected JSONObject doInBackground(String... args) {
HTTPHandler sh = new HTTPHandler();
String login_URL = "http://2f179dfb.ngrok.io/getsong.php";
try {
//Fetching the boolean value form sharedpreferences
URL url = new URL(login_URL);
HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
httpURLConnection.setRequestMethod("POST");
httpURLConnection.setDoOutput(true);
httpURLConnection.setDoInput(true);
InputStream inputStream = httpURLConnection.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream, "iso-8859-1"));
result = "";
String line = "";
while ((line = bufferedReader.readLine()) != null) {
result += line;
}
bufferedReader.close();
inputStream.close();
httpURLConnection.disconnect();
Log.e("RESULT", result);
JSONObject jsonObject = new JSONObject(result);
JSONArray result1 = jsonObject.getJSONArray("result");
for (int i = 0; i < result1.length(); i++) {
JSONObject c = result1.getJSONObject(i);
String id = c.getString("songID");
String names = c.getString("songName");
String ss = c.getString("singerName");
listofsoongs.add(new songsarray(ss,id,names));
}
return jsonObject;
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(JSONObject json) {
pDialog.dismiss();
//EDIT 3: set your adapter here as this method will be called on the UI Thread
itemsAdapter = new MyCustomAdapterSongs(this, listofsoongs);
listView.setAdapter(itemsAdapter);
}
}
}
}
`
i have classes in my projects that only does the server operations such as getting and putting data. i have class which populating list and then method to get this list. the problem is that i'm calling the "getList" method and the background operation hasent finished then i get null from the "getList" method
this is my AsyncTask class, as you can see the "getList" suppose to give me the list completed
public class GetRoomatesListActivity extends AsyncTask<String, String, String> {
private ArrayList<RoomateModel> tmpList;
private ArrayList<RoomateModel> completeList;
DBHelper db;
Context context;
public GetRoomatesListActivity(Context context){
this.context = context;
}
#Override
protected String doInBackground(String... params) {
db = DBHelper.getInstance(context);
HttpURLConnection connection = null;
BufferedReader reader = null;
tmpList = new ArrayList<RoomateModel>();
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);
}
String finalJson = buffer.toString();
JSONObject parentObject = new JSONObject(finalJson);
JSONArray parentArray = parentObject.getJSONArray("result");//creates array of Roomates of the selected apartment
for (int i = 0; i < parentArray.length(); i++) {
JSONObject finalObject = parentArray.getJSONObject(i);//get the cuttent json object which is representaion of roomate object
String Fname = finalObject.getString("firstName");
String Lname = finalObject.getString("lastName");
String phone = finalObject.getString("phone");
RoomateModel item = new RoomateModel(Fname, Lname, phone);//creates roomates model with the current item data from the array
tmpList.add(item);//adds the roomate to the list of roomates
//add the roomates to local data base
db.addRoomate(item,apartment);
}
return null;
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException 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 s) {
super.onPostExecute(s);
completeList = tmpList;
}
public ArrayList<RoomateModel> getList(){
return completeList;
}
}
and this is the class which im trying to get the list to in order to use it but its retrieving null
public class roomatesScreen extends Activity {
ListView items;
ArrayList<RoomateModel> list; //list to compare with the list rerived from GetRoomatesListActivity
RoomatesAdapter adapter;
DBHelper db;
ApartmentModel apartment;
SharedPreferences preferences;
GetRoomatesListActivity r;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.roomates_list);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
items = (ListView) findViewById(R.id.roomatesList);
db = DBHelper.getInstance(this);
Bundle bundle = getIntent().getExtras();
int number = bundle.getInt("number");
apartment = new ApartmentModel(number);// creates apartment model with the user's apartment number
final String num = Integer.toString(number);
r = new GetRoomatesListActivity(this);
r.execute("this is the link to my query" + num);
list = r.getList(); //here list is null
adapter = new RoomatesAdapter(roomatesScreen.this, list);
items.setAdapter(adapter);//here application crushes because of nullPointerExpeption
The best way is to perform the update on UI is in PostExecute method of AsyncTask..
At the time you are accessing it, the control is in the doInBackground method. So your list is null at that time.
put this
#Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
adapter = new RoomatesAdapter(roomatesScreen.this, tmpList);
items.setAdapter(adapter);/
}
into the onPostExecute().
2nd solution
Initialize the list when you are setting it to adapter. like:
list = new ArrayList();
and rest work (update the list and call notifyDataSetChanged() on adapter object) in onPostExecute().
Change doInBackground() method return type
public class GetRoomatesListActivity extends AsyncTask<String, String, ArrayList<Object>> {
private ArrayList<RoomateModel> tmpList;
private ArrayList<RoomateModel> completeList;
DBHelper db;
Context context;
public GetRoomatesListActivity(Context context){
this.context = context;
}
#Override
protected ArrayList<Object> doInBackground(String... params) {
db = DBHelper.getInstance(context);
HttpURLConnection connection = null;
BufferedReader reader = null;
tmpList = new ArrayList<RoomateModel>();
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);
}
String finalJson = buffer.toString();
JSONObject parentObject = new JSONObject(finalJson);
JSONArray parentArray = parentObject.getJSONArray("result");//creates array of Roomates of the selected apartment
for (int i = 0; i < parentArray.length(); i++) {
JSONObject finalObject = parentArray.getJSONObject(i);//get the cuttent json object which is representaion of roomate object
String Fname = finalObject.getString("firstName");
String Lname = finalObject.getString("lastName");
String phone = finalObject.getString("phone");
RoomateModel item = new RoomateModel(Fname, Lname, phone);//creates roomates model with the current item data from the array
tmpList.add(item);//adds the roomate to the list of roomates
//add the roomates to local data base
db.addRoomate(item,apartment);
}
return null;
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException 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 s) {
super.onPostExecute(s);
completeList = tmpList;
}
public ArrayList<RoomateModel> getList(){
return completeList;
}
}
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);
}
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);
}
}