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);
}
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 want to get Google spreadsheet data to my Android app.
I have looked for some example.
https://www.telerik.com/blogs/google-spreadsheet-as-data-source-android
This is a sample that I found.
It can run, but when I change his spreadsheet to my spreadsheet.
It will fail.
I do not know what's wrong.
This is my sheet:
https://docs.google.com/spreadsheets/d/1pIj08MUjTNZscHbKkbJJ2eNR1RYlhJLW7qDrcWRnJMM/edit?usp=sharing
This is my Code:
AsyncResult.java
interface AsyncResult
{ void onResult(JSONObject object);
}
DownloadWebpageTask.java
public class DownloadWebpageTask extends AsyncTask<String, Void, String> {
AsyncResult callback;
public DownloadWebpageTask(AsyncResult callback) {
this.callback = callback;
}
#Override
protected String doInBackground(String... urls) {
// params comes from the execute() call: params[0] is the url.
try {
return downloadUrl(urls[0]);
} catch (IOException e) {
return "Unable to download the requested page.";
}
}
// onPostExecute displays the results of the AsyncTask.
#Override
protected void onPostExecute(String result) {
// remove the unnecessary parts from the response and construct a JSON
int start = result.indexOf("{", result.indexOf("{") + 1);
int end = result.lastIndexOf("}");
String jsonResponse = result.substring(start, end);
try {
JSONObject table = new JSONObject(jsonResponse);
callback.onResult(table);
} catch (JSONException e) {
e.printStackTrace();
}
}
private String downloadUrl(String urlString) throws IOException {
InputStream is = null;
try {
URL url = new URL(urlString);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setReadTimeout(10000 /* milliseconds */);
conn.setConnectTimeout(15000 /* milliseconds */);
conn.setRequestMethod("GET");
conn.setDoInput(true);
// Starts the query
conn.connect();
int responseCode = conn.getResponseCode();
is = conn.getInputStream();
String contentAsString = convertStreamToString(is);
return contentAsString;
} finally {
if (is != null)
is.close();
}
}
private String convertStreamToString(InputStream is) {
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
StringBuilder sb = new StringBuilder();
String line = null;
try {
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
} catch (IOException e) {}
return sb.toString();
}
}
Team.java
public class Team {
private String position;
public Team(String position)
{
this.setPosition(position);
}
public String getPosition() {
return position;
}
public void setPosition(String position) {
this.position = position;
}
}
TeamsAdapter.java
public class TeamsAdapter extends ArrayAdapter<Team> {
Context context;
private ArrayList<Team> teams;
public TeamsAdapter(Context context, int textViewResourceId, ArrayList<Team>
items) {
super(context, textViewResourceId, items);
this.context = context;
this.teams = items;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
View v = convertView;
if (v == null) {
LayoutInflater vi = (LayoutInflater)
context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = vi.inflate(R.layout.team, null);
}
Team o = teams.get(position);
if (o != null) {
TextView pos = (TextView) v.findViewById(R.id.position);
pos.setText(String.valueOf(o.getPosition()));
}
return v;
}
}
mainactivity.java
public class MainActivity extends AppCompatActivity {
private static final String DEBUG_TAG = "HttpExample";
ArrayList<Team> teams = new ArrayList<Team>();
ListView listview;
Button btnDownload;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listview = (ListView) findViewById(R.id.listview);
btnDownload = (Button) findViewById(R.id.btnDownload);
ConnectivityManager connMgr = (ConnectivityManager)
getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();
if (networkInfo != null && networkInfo.isConnected()) {
btnDownload.setEnabled(true);
} else {
btnDownload.setEnabled(false);
}
}
public void buttonClickHandler(View view) {
new DownloadWebpageTask(new AsyncResult() {
#Override
public void onResult(JSONObject object) {
processJson(object);
}
}).execute("https://spreadsheets.google.com/tq?
key=1pIj08MUjTNZscHbKkbJJ2eNR1RYlhJLW7qDrcWRnJMM");
}
private void processJson(JSONObject object) {
try {
JSONArray rows = object.getJSONArray("rows");
for (int r = 0; r < rows.length(); ++r) {
JSONObject row = rows.getJSONObject(r);
JSONArray columns = row.getJSONArray("c");
String position = columns.getJSONObject(0).getString("v");
Team team = new Team(position);
teams.add(team);
}
final TeamsAdapter adapter = new TeamsAdapter(this, R.layout.team,
teams);
listview.setAdapter(adapter);
} catch (JSONException e) {}
}
}
That's the link you should be using
https://spreadsheets.google.com/feeds/list/1pIj08MUjTNZscHbKkbJJ2eNR1RYlhJLW7qDrcWRnJMM/od6/public/values?alt=json
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'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);
}
I'm new to making android apps. I'm trying to make a simple app that pulls movie data from themoviedb.org and displays the posters from the movie on the main page. I'm using GridView and ImageView with a custom adapter but the screen shows up blank. I'm not sure what I need to do to get the images to show up.
Custom adapter:
public class CustomImageAdapter extends BaseAdapter {
private Context mContext;
private String[] inputs;
private List<ImageView> imageList;
LayoutInflater inflater;
public CustomImageAdapter(Context c, String[] inputs) {
mContext = c;
this.inputs = inputs;
inflater = (LayoutInflater) this.mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
public int getCount() {
return inputs.length;
}
public Object getItem(int position) {
return imageList.get(position);
}
public long getItemId(int position) {
return position;
}
public void add(String[] results) {
inputs = results;
imageList = new ArrayList<ImageView>();
for (int i = 0; i < inputs.length; i++){
ImageView imageView = new ImageView(mContext);
Picasso.with(mContext)
.load(inputs[i])
.into(imageView);
imageList.add(imageView);
}
}
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = (LayoutInflater) mContext
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View gridView;
if (convertView == null) {
gridView = new View(mContext);
convertView = inflater.inflate(R.layout.grid_layout, null);
ImageView imageView = (ImageView) gridView.findViewById(R.id.grid_layout_image_view);
imageView = imageList.get(position);
} else {
gridView = (View) convertView;
}
return gridView;
}
}
Main Fragment:
public class GridFragment extends Fragment {
private static ImageView imageView;
private static String[] jsonStringHolder = new String[1];
private static CustomImageAdapter customImageAdapter;
private static GridView gridView;
public GridFragment() {
}
#Override
public void onStart() {
super.onStart();
FetchMovieTask fetchMovieTask = new FetchMovieTask();
fetchMovieTask.execute();
}
private void loadImageView(String[] result) {
try {
getMovieDataFromJson(result);
} catch (JSONException e) {
Log.e("LOG_TAG", e.getMessage(), e);
e.printStackTrace();
}
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
//customImageAdapter = new CustomImageAdapter(getContext(), null);
gridView = (GridView) rootView.findViewById(R.id.grid_view);
//gridView.setAdapter(customImageAdapter);
return rootView;
}
private void getMovieDataFromJson(String[] jsonStringHolder)
throws JSONException {
final String OWM_POSTER_PATH = "poster_path";
final String OWM_RESULTS = "results";
String movieJsonStr = jsonStringHolder[0];
JSONObject movieJsonObject = new JSONObject(movieJsonStr);
JSONArray movieJsonArray = movieJsonObject.getJSONArray(OWM_RESULTS);
String[] resultStrs = new String[movieJsonArray.length()];
for (int i = 0; i < movieJsonArray.length(); i++) {
JSONObject movieDescriptionJsonObject = movieJsonArray.getJSONObject(i);
String posterPathPlaceholder =
movieDescriptionJsonObject.getString(OWM_POSTER_PATH);
final String FORECAST_BASE_URL =
"http://api.themoviedb.org/3/movie/";
final String SIZE = "w185";
resultStrs[i] = FORECAST_BASE_URL + SIZE + posterPathPlaceholder;
}
customImageAdapter = new CustomImageAdapter(getContext(), null);
customImageAdapter.add(resultStrs);
gridView.setAdapter(customImageAdapter);
}
public class FetchMovieTask extends AsyncTask<Void, Void, String[]> {
private final String LOG_TAG = FetchMovieTask.class.getSimpleName();
#Override
protected String[] doInBackground(Void... params) {
HttpURLConnection urlConnection = null;
BufferedReader reader = null;
// Will contain the raw JSON response as a string.
String movieJsonStr = null;
// String format = "json";
//String units = "metric";
//int numDays = 7;
try {
// Construct the URL for the OpenWeatherMap query
// Possible parameters are avaiable at OWM's forecast API page, at
// http://openweathermap.org/API#forecast
final String FORECAST_BASE_URL =
"http://api.themoviedb.org/3/movie/";
final String PREFERENCE = "now_playing?";
final String API_KEY = "api_key=e0cbb327025cf835dfc53ca51d11db68";
//final String UNITS_PARAM = "units";
//final String DAYS_PARAM = "cnt";
String urlString = FORECAST_BASE_URL + PREFERENCE + API_KEY;
URL url = new URL(urlString);
// 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.
return 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.
return null;
}
movieJsonStr = buffer.toString();
} catch (IOException e) {
Log.e(LOG_TAG, "Error pits", e);
// If the code didn't successfully get the weather data, there's no point in attemping
// to parse it.
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);
}
}
}
String[] movieJsonStrArray = new String[1];
movieJsonStrArray[0] = movieJsonStr;
return movieJsonStrArray;
}
#Override
protected void onPostExecute(String[] result) {
if (result != null) {
jsonStringHolder[0] = result[0];
}
loadImageView(result);
}
}
XML:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
android:paddingBottom="#dimen/activity_vertical_margin" tools:context=".MainActivityFragment">
<GridView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="#+id/grid_view"
android:layout_alignParentBottom="true"
android:layout_centerInParent="true">
</GridView>
<ImageView xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/grid_layout_image_view" />
</RelativeLayout>
if you are trying to fill a list with rows, and you are new to android, perhaps, you should try extending from ListActivity or FragmentList, see the google guide at http://developer.android.com/guide/topics/ui/layout/listview.html , ListActivity and FragmentList are helper clases, they have a method "setListAdapter" that do the trick.