I'm trying to download images for each artist that has music on my phone, then show these images in a GridView. I'm using the lastfm-java library that Last.fm recommends using. The method you call to fetch an artists image is getImageURL(ImageSize size), but before you do this, you need to tell it which artist you want to reference with a String parameter. So, in full it would be something like this:
#Override
protected String doInBackground(Object... arg0) {
Artist artist = Artist.getInfo(artistOrMbid, LASTFM_API_KEY);
return artist.getImageURL(ImageSize.EXTRALARGE);
}
Getting all the artists that are on my phone isn't a problem, you just reference MediaStore. You would do something like this:
private void getArtists() {
String[] projection = new String[] {
MediaStore.Audio.Artists._ID, MediaStore.Audio.Artists.ARTIST,
};
String sortOrder = MediaStore.Audio.Artists.DEFAULT_SORT_ORDER;
Cursor c = getActivity().getContentResolver().query(
MediaStore.Audio.Artists.EXTERNAL_CONTENT_URI, projection, null, null, sortOrder);
if (c != null) {
int count = c.getCount();
if (count > 0) {
final int ARTIST_IDX = c.getColumnIndex(MediaStore.Audio.Artists.ARTIST);
for (int i = 0; i < count; i++) {
c.moveToPosition(i);
}
}
c.close();
c = null;
}
}
The Adapter for my GridView isn't anything special, it simply extends BaseAdapter.
Note AQuery is a library I'm using that helps cache and load a Bitmap from a URL.
public class GridViewAdapter extends BaseAdapter {
private final String[] imageURLs;
private final LayoutInflater mInflater;
private final Activity mActivity;
public GridViewAdapter(String[] urls, Activity activity) {
imageURLs = urls;
mActivity = activity;
mInflater = (LayoutInflater)mActivity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
#Override
public int getCount() {
return imageURLs.length;
}
#Override
public Object getItem(int position) {
return position;
}
#Override
public long getItemId(int position) {
return position;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder viewholder = null;
// Inflate GridView items
if (convertView == null) {
convertView = mInflater.inflate(R.layout.gridview_items, null);
viewholder = new ViewHolder();
viewholder.mImage = (ImageView)convertView.findViewById(R.id.gridview_image);
convertView.setTag(viewholder);
} else {
viewholder = (ViewHolder)convertView.getTag();
}
AQuery aq = new AQuery(convertView);
aq.id(viewholder.mImage).image(imageURLs[position], false, false, 0, 0, null, 0, 0.75f);
return convertView;
}
}
class ViewHolder {
public ImageView mImage;
}
So in full, my AsyncTask is as follows:
public class LastfmArtistGetImageURL extends AsyncTask<Object, Integer, String[]> implements
Constants {
private static final String tag = LastfmArtistGetImageURL.class.getSimpleName();
private GridViewAdapter mGridAdapter;
// Test
private final String[] imageIds = {
"http://userserve-ak.last.fm/serve/252/71875544.png",
"http://userserve-ak.last.fm/serve/252/6258507.jpg",
"http://userserve-ak.last.fm/serve/252/51274303.png",
"http://userserve-ak.last.fm/serve/252/58672183.png",
"http://userserve-ak.last.fm/serve/252/72029714.png",
"http://userserve-ak.last.fm/serve/252/17666215.jpg",
"http://userserve-ak.last.fm/serve/252/63247381.png",
"http://userserve-ak.last.fm/serve/252/33665463.jpg"
};
private final String artistOrMbid;
private final GridView mGridView;
private final Activity mActivity;
public LastfmArtistGetImageURL(String name, GridView gv, Activity activity) {
artistOrMbid = name;
mGridView = gv;
mActivity = activity;
}
#Override
protected String[] doInBackground(Object... arg0) {
Artist artist = Artist.getInfo(artistOrMbid, LASTFM_API_KEY);
Collection<String> col = new ArrayList<String>();
col.add(artist.getImageURL(ImageSize.EXTRALARGE));
return col.toArray(new String[0]);
}
#Override
protected void onPostExecute(String[] result) {
if (result != null)
mGridAdapter = new GridViewAdapter(imageIds, mActivity);
mGridView.setAdapter(mGridAdapter);
super.onPostExecute(result);
}
}
When I call my AsyncTask, I call it in my getArtists() method like this:
new LastfmArtistGetImageURL(c.getString(ARTIST_IDX), mGridView, getActivity())
.execute();
Problem
When I call this, all of the artists images download, but they download one after the other at position 0 of my GridViewAdapter. In other words, one image loads, then next, and so on all in the first position when I need them to be placed into each available position in the GridView. When I return my test String[] in my AsyncTask everything works like it should. All of the images are placed in order in each available space in the GridView.
Question
My question is, how do I return each artist image I download into my GridView correctly and why are the images currently only being loaded at the first position in my GridViewAdapter?
Edit - Shubhayu's answer
I moved setting my GridViewAdapter into my getArtists() method like so. This results in all the images being downloaded (As says LogCat), but only the last one being set in my GridView.
String[] test = new LastfmArtistGetImageURL(c.getString(ARTIST_IDX),
mGridView, getActivity()).execute().get();
mGridAdapter = new GridViewAdapter(test, getActivity());
mGridView.setAdapter(mGridAdapter);
smoak's answer
This results in only the last artist image (by the default order) being downloaded and applied in my GridView.
String[] test = {c.getString(ARTIST_IDX)};
new LastfmArtistGetImageURL(test, mGridView, getActivity()).execute();
Your AsyncTask looks like you are executing it each time for each Artist. Thus, your AsyncTask returns only one Artist's image and your GridView gets that Artists image, then you run the AsyncTask for the next Artist, GridView gets updated with new image and so on. What you need to do is modify your AsyncTask to take a String array of Artist names and loop over them in the doInBackground to get their image's.
// ... SNIPPED
public LastfmArtistGetImageURL(String[] names, GridView gv, Activity activity) {
artistsOrMbids = names;
mGridView = gv;
mActivity = activity;
}
#Override
protected String[] doInBackground(Object... arg0) {
Collection<String> col = new ArrayList<String>();
for (String nameOrMbid : this.artistsOrMbids) {
Artist artist = Artist.getInfo(artistOrMbid, LASTFM_API_KEY);
col.add(artist.getImageURL(ImageSize.EXTRALARGE));
}
return col.toArray(new String[0]);
}
// .... SNIPPED
And pass in all the artist names:
String[] artists = { "The Black Keys", "Rush", "The Allman Brothers" };
new LastfmArtistGetImageURL(artists, mGridView, getActivity()).execute();
here's what is happening, when you pass the test string it has a list of images and hence the gridview shows them properly. but when you use it to download an image for each artist, things go wrong.
Every time you call
new LastfmArtistGetImageURL(c.getString(ARTIST_IDX), mGridView, getActivity()).execute();
it runs the doInBackground(), completes it and then immediately calls the onPostExecute() where it creates a new adapter and passes your result which basically contains a single image of the single call.
So what u need to do is in your asynctask download all the images and then create a single adapter and pass all the images to it. That is not happening currently.
EDIT
If you see the AsyncTask, you will realize that everytime you call it, the string array returns only one image. So instead of returning a string array, return a string.
Next, I would suggest you use an ArrayList in your Adapter instead of a String array.
In your getArtists(), create an ArrayList and everytime you call
new LastfmArtistGetImageURL(test, mGridView, getActivity()).execute();
add the result to your ArrayList. Once you have looped through all the artists, your ArrayList will contain all the images.
Now set it to the Adapter. (You would have t change the adapter a bit if you change it from string to arraylist.)
Related
I am working on a project where I have a let's say 5x5 grid of TextViews and I want to check if an entire row or column has equal elements. I am using an Adapter class to inflate my gridview with simply one textview element. Here is the code that I have tried but I cannot seem to make it work:
final int size = gridView.getCount(); //25
int temp = 0;
for (int i = 0; i < size; i++) {
ViewGroup gridChild = (ViewGroup) gridView.getChildAt(i);
childSize = gridChild.getChildCount();
for (int j = 0; j < childSize; j++) {
if (gridChild.getChildAt(j) instanceof TextView &&
((TextView) gridChild.getChildAt(j)).getText().toString().equals("x")) {
temp++;
}
The thing is when i tried to debug, debugger showed null values for childSize variable and could not properly get the value from getChildAt. Basically, what I am trying to do is get inside the if statement. Also this is the first time I am working with ViewGroup calss, and the methods that I call. Any help would be appreciated.
Edit:I am looking for a way to do this outside the getView method in the adapter class and not in a onClick method as well. (Code sample answers would be highly appreciated). Also, the getChildAt method call returns null so the code I have shown would not work because I am assigning a null value to the gridChild.
This is the onClick that I use for the TextViews:
`
public void numberFill(View view) {
if (((TextView) view).getText().toString().isEmpty()) {
((TextView) view).setText(String.valueOf(numbCounter + 1));
numbCounter++;
}
else if (!((TextView) view).getText().toString().isEmpty() && numbCounter >= 16) {
((TextView) view).setText("x");
}
}
This is my adapter class:
public class GridAdapter extends BaseAdapter {
private final Context mContext;
private String[] numbers;
public GridAdapter(Context context, String[] numbers) {
this.mContext = context;
this.numbers = numbers;
}
#Override
public int getCount() {
return numbers.length;
}
#Override
public long getItemId(int position) {
return 0;
}
#Override
public Object getItem(int position) {
return numbers[position];
//return null;
}
#Override
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);
gridView = inflater.inflate(R.layout.textview_layout, null);
TextView textView = (TextView) gridView.findViewById(R.id.cell);
textView.setText(numbers[position]);
} else {
gridView = (View) convertView;
}
return gridView;
}
}
numberFill reworked:
public void numberFill(View view) {
int index = (Integer) view.getTag();
if (numbers[index].toString().isEmpty()) {
numbers[index] = String.valueOf(numbCounter + 1);
numbCounter++;
}
else if (!numbers[index].toString().isEmpty() && numbCounter >= 25) {
numbers[index] = "x";
}
gridAdapter.notifyDataSetChanged();
}
`
When using an AdapterView – such as your GridView – you generally don't want to directly access and manipulate its child Views outside of its Adapter. Instead, the dataset backing the Adapter should be updated, and the GridView then refreshed.
In your case, you presumably have a setup similar to this in your Activity:
private GridAdapter gridAdapter;
private String[] numbers;
#Override
protected void onCreate(Bundle savedInstanceState) {
...
numbers = new String[25];
gridAdapter = new GridAdapter(this, numbers);
}
Here, the numbers array is what you want to directly modify, rather than the text on the GridView's child TextViews. That array is then easily iterated over to do your row and column value checks.
Since the array will be modified in the Activity, we need a way to pass the clicked TextView's position in the Adapter to the Activity's click method, as we'll need it to access the correct array element. For this, we can utilize the tag property available on all View's, via the setTag() and getTag() methods. For example, in GridAdapter's getView() method:
...
TextView textView = (TextView) gridView.findViewById(R.id.cell);
textView.setText(numbers[position]);
textView.setTag(position);
...
In the click method, the position can be easily retrieved with getTag(), and used as the index to get the clicked TextView's text from the numbers array. You can then do the necessary processing or calculation with that text, set the modified value back to the array element, and trigger a refresh on the Adapter.
public void numberFill(View view) {
int index = (Integer) view.getTag();
// Do your processing with numbers[index]
numbers[index] = "new value";
gridAdapter.notifyDataSetChanged();
}
The notifyDataSetChanged() call will cause the GridView to update its children, and your new value will be set in the appropriate TextView. The numbers array now also has the current values, and is readily available in the Activity to perform the necessary checks there.
I'm writing a simple program to request a JOSN request of a list of earthquakes to display for users. I use Asynctask to put the request in the background thread and use an ArrayList Adaptor to display the relevant information. I declare an empty ArrayList and then extract the JOSN request and put them in a temporary list and then assign the temporary list to the empty ArrayList.
I use a debugger tool to see that in the updateEarthquakeList method. I set the break point in the updateEarthquakeList method. this.earthquak and earthquakes both have 10 elements. Pics are as follow:
But when I set the break point after task.execute(USGS_REQUEST_URL) in the onCreate method, I got this:
As the pics shown after execute the AsyncTask the ArrayList is empty. But inside the AsyncTask The array was actually updated. (To do a little experiment I create an int haha as 0 and change it to 1 in the Asynctask, but it changed back to 0 afterwards)
How is this happen and how do I supposted to make it right?
public class EarthquakeActivity extends AppCompatActivity {
public static final String LOG_TAG = EarthquakeActivity.class.getName();
ArrayList<Earthquake> earthquak = new ArrayList<Earthquake>();
int haha = 0;
private static final String USGS_REQUEST_URL = "http://earthquake.usgs.gov/fdsnws/event/1/query?format=geojson&eventtype=earthquake&orderby=time&minmag=6&limit=10";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.earthquake_activity);
EarthquakeAsyncTask task = new EarthquakeAsyncTask();
task.execute(USGS_REQUEST_URL);
// Create a fake list of earthquake locations.
// Find a reference to the {#link ListView} in the layout
ListView earthquakeListView = (ListView) findViewById(R.id.list);
// Create a new {#link ArrayAdapter} of earthquakes
EarthquakeAdapter adapter = new EarthquakeAdapter(this, earthquak);
// Set the adapter on the {#link ListView}
// so the list can be populated in the user interface
earthquakeListView.setAdapter(adapter);
//OPEN a web page of a specific when textview is clicked.
earthquakeListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
Intent intent = new Intent(Intent.ACTION_VIEW, earthquak.get(position).getUrl());
if (intent.resolveActivity(getPackageManager()) != null) {
startActivity(intent);
}
}
});
}
private void updateEarthquakeList(ArrayList<Earthquake> earthquake) {
this.earthquak = earthquake;
haha = 1;
}
private class EarthquakeAsyncTask extends AsyncTask<String, Void, ArrayList<Earthquake>> {
#Override
protected ArrayList<Earthquake> doInBackground(String... urls) {
if (urls.length < 1 || urls[0] == null) {
return null;
}
ArrayList<Earthquake> earthquakes = QueryUtils.fetchEarthquakeData(urls[0]);
return earthquakes;
}
#Override
protected void onPostExecute(ArrayList<Earthquake> earthquakes) {
updateEarthquakeList(earthquakes);
}
}
This question has been answered before, but the solutions doesn't seem to work for me. I would like to know what the best way is to save an ArrayList.
I generate an ArrayList with all the installed applications on the phone. This list is shown in a ListView where the user can (de)select apps. This is all working fine. What I would like is that the Arraylist gets saved when the user presses a save button or when the activity calls onPause().
When the user returns to the list the user will see the list the way he saved/left it.
Here is my code:
onCreate
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_app_list);
loadApps();
loadListView();
addClickListener();
}
loadApps
private void loadApps(){
manager = getPackageManager();
apps = new ArrayList<AppDetail>();
if(apps.size()==0) {
Intent i = new Intent(Intent.ACTION_MAIN, null);
i.addCategory(Intent.CATEGORY_LAUNCHER);
List<ResolveInfo> availableActivities = manager.queryIntentActivities(i, 0);
for (ResolveInfo ri : availableActivities) {
AppDetail app = new AppDetail();
app.label = ri.loadLabel(manager);
app.name = ri.activityInfo.packageName;
app.icon = ri.activityInfo.loadIcon(manager);
app.allowed = false;
apps.add(app);
}
Log.i("applist", apps.toString());
}
}
AppDetail.class
public class AppDetail {
CharSequence label;
CharSequence name;
Drawable icon;
Boolean allowed;
loadListView
private void loadListView(){
list = (ListView)findViewById(R.id.apps_list);
adapter = new ArrayAdapter<AppDetail>(this, R.layout.list_item, apps) {
#Override
public View getView(int position, View convertView, ViewGroup parent) {
if(convertView == null){
convertView = getLayoutInflater().inflate(R.layout.list_item, null);
}
ImageView appIcon = (ImageView)convertView.findViewById(R.id.item_app_icon);
appIcon.setImageDrawable(apps.get(position).icon);
TextView appLabel = (TextView)convertView.findViewById(R.id.item_app_label);
appLabel.setText(apps.get(position).label);
TextView appName = (TextView)convertView.findViewById(R.id.item_app_name);
appName.setText(apps.get(position).name);
if(list.isItemChecked(position)){convertView.setBackgroundColor(getResources().getColor(R.color.green));}
if(!list.isItemChecked(position)){convertView.setBackgroundColor(getResources().getColor(R.color.white));}
return convertView;
}
};
list.setAdapter(adapter);
list.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
}
addClickListener
private void addClickListener() {
list.setOnItemClickListener(new AdapterView.OnItemClickListener() {
public void onItemClick(AdapterView<?> av, View v, int pos,
long id) {
checked = list.getCheckedItemPositions();
ArrayList<AppDetail> allowedApps = new ArrayList<>();
for (int i = 0; i < checked.size(); i++) {
// Item position in adapter
int position = checked.keyAt(i);
// Add sport if it is checked i.e.) == TRUE!
if (checked.valueAt(i)) {
allowedApps.add(adapter.getItem(position));
}
}
adapter.notifyDataSetChanged();
Log.i("", allowedApps.toString());
}
});
}
At this moment I'm creating two lists:
List: list of all apps
AllowedApps: list of checked (allowed) apps, to use in an other activity
If you need saving your list when activity is paused, you have several ways to do it. First you need define the private list field in your activity.
private ArrayList<AppDetail> allowedApps;
1) Make AppDetail serializable and use onSaveInstanceState
public class AppDetail implements Serializable {
CharSequence label;
CharSequence name;
Drawable icon;
Boolean allowed;
}
---------------- EDIT -----------------
I would change Drawable icon field for int icon.
In your loadApps() method change the setence app.icon = ri.activityInfo.getIconResource();
In yout loadListView method change the setence appIcon.setImageResource(apps.get(position).icon);
#Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putSerializable("allowedApps", allowedApps);
}
Retrieve the list in onCreate method
if (savedInstanceState != null) {
allowedApps = (List<AppDetail>)savedInstanceState.getSerializable("allowedApps");
}else{
allowedApps = new ArrayList<AppDetail>();
}
2) Use onRetainCustomNonConfigurationInstance
Return the list in onRetainCustomNonConfigurationInstance
#Override
public Object onRetainCustomNonConfigurationInstance() {
return allowedApps;
}
Retrieve the list in onCreate method
Object allowedApps= getLastCustomNonConfigurationInstance();
if (allowedApps != null) {
this.allowedApps = (List<AppDetail>) allowedApps;
}else{
this.allowedApps = new ArrayList<AppDetail>();
}
I think you are looking for something like "Parcelable". It can save any ArrayList and retrieve back when you need it just like the Shared Preferences.
Please have a look here,
How to save custom ArrayList on Android screen rotate?
ArrayList is serializable. Save it as a serializable object in file on storage
I've searched all the posts I can find, and none seem to help with my situation. I have an android project that uses web services to pull down hourly weather data and populate a listView with the results.
The weird problem I'm having is that when I debug the project on my android phone, the main activity is blank and the listView isn't populated. If I run the project from android studio with my phone locked, and then unlock my phone the app opens on my phone with all of the listView properly formatted and populated.
I feel like it's a race condition issue between the asynctask and the adapter, but I can't seem to resolve it. I tried making my asyncTask an inner private class and calling notifyDataSetChanged on the adapter inside the onPostExecute method, but to no avail. I feel it must be something simple, but I'm relatively new to Android dev, so I'm stuck.
I have three classes that I'll post the pertinent code from
MainActivity.java (onCreate)
public class MainActivity extends ActionBarActivity {
ArrayList<Weather> w = new ArrayList<Weather>();
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
DownloadWeatherTask myTask = new DownloadWeatherTask(w);
WeatherAdapter myAdapter = new WeatherAdapter(this,w);
ListView l = (ListView) findViewById(R.id.weatherList);
l.setAdapter(myAdapter);
myTask.execute();
}
}
WeatherAdapter.java
public class WeatherAdapter extends ArrayAdapter<Weather>{
public WeatherAdapter(Context context, ArrayList<Weather> weather) {
super(context, R.layout.item_weather, weather);
}
public View getView(int position, View convertView, ViewGroup parent) {
// Get the data item for this position
Weather forecast = getItem(position);
// Check if an existing view is being reused, otherwise inflate the view
if (convertView == null) {
convertView = LayoutInflater.from(getContext()).inflate(R.layout.item_weather, parent, false);
}
// Lookup view for data population
TextView tvTime = (TextView) convertView.findViewById(R.id.listTime);
TextView tvDescr = (TextView) convertView.findViewById(R.id.listDescr);
TextView tvTemp = (TextView) convertView.findViewById(R.id.listTemp);
TextView tvHumid = (TextView) convertView.findViewById(R.id.listHumid);
ImageView ivWeather = (ImageView) convertView.findViewById(R.id.weatherImg);
// Populate the data into the template view using the data object
tvTime.setText(forecast.time);
tvDescr.setText(forecast.description);
tvTemp.setText(forecast.temperature+"°(F)");
tvHumid.setText(forecast.humidity+"% humidity");
ivWeather.setImageBitmap(forecast.weatherImg);
// Return the completed view to render on screen
return convertView;
}
}
DownloadWeatherTask.java
public class DownloadWeatherTask extends AsyncTask<Void,Void,Void>{
ArrayList<Weather> data;
public DownloadWeatherTask(ArrayList<Weather> a){
data = a;
}
public ArrayList<Weather> getData() {
return data;
}
protected Void doInBackground(Void...params) {
try {
String website = "http://api.wunderground.com/api/1111111111111/geolookup/q/autoip.json";
URL site = new URL(website);
HttpURLConnection weatherUnderground = (HttpURLConnection) site.openConnection();
weatherUnderground.connect();
JsonParser weatherParser = new com.google.gson.JsonParser();
JsonElement weatherJson = weatherParser.parse(new InputStreamReader((InputStream) weatherUnderground.getContent()));
JsonObject weatherObj = weatherJson.getAsJsonObject();
String zip = weatherObj.get("location").getAsJsonObject().get("zip").getAsString();
String city = weatherObj.get("location").getAsJsonObject().get("city").getAsString();
String state = weatherObj.get("location").getAsJsonObject().get("state").getAsString();
String hourly = "http://api.wunderground.com/api/111111111111/hourly/q/" + state + "/" + city + ".json";
URL hourlySite = new URL(hourly);
HttpURLConnection hourlyConnection = (HttpURLConnection) hourlySite.openConnection();
hourlyConnection.connect();
com.google.gson.JsonParser hourlyParser = new com.google.gson.JsonParser();
JsonElement hourlyWeatherJson = weatherParser.parse(new InputStreamReader((InputStream) hourlyConnection.getContent()));
JsonArray weatherArr = hourlyWeatherJson.getAsJsonObject().get("hourly_forecast").getAsJsonArray();
int l = weatherArr.size();
for (int i = 0; i < l; i++) {
String date = weatherArr.get(i).getAsJsonObject().get("FCTTIME").getAsJsonObject().get("pretty").getAsString();
String temp = weatherArr.get(i).getAsJsonObject().get("temp").getAsJsonObject().get("english").getAsString();
String condition = weatherArr.get(i).getAsJsonObject().get("condition").getAsString();
String humidity = weatherArr.get(i).getAsJsonObject().get("humidity").getAsString();
String iconUrl = weatherArr.get(i).getAsJsonObject().get("icon_url").getAsString();
Bitmap icon = getBitmapFromURL(iconUrl);
data.add(new Weather(date, condition, temp, humidity, icon));
}
} catch (IOException e) {
Log.e("Error: ",e.toString());
}
return null;
}
protected void onPostExecute(Void...params){
}
}
Below are links to my screenshots showing the app not populating the listView, and the app working properly when the program is run while the phone is initially locked.
Any help would be greatly appreciated!!
Thanks
In postExecute(), you need to update the adapter's List and then invoke its notifyDataSetChanged method. I suspect that you were forgetting to update the adapter's data.
The other option is to create a new adapter with the new data, and set the new adapter on the ListView.
I figured out what the issue was! I hadn't added #Override to my onPostExecute() method so it was never being called.
I added the notifyDataSetChanged to my onPostExecute as suggested, which worked once I added the #override to my method.
In one of my android activity, I've a ListView lvFeedsList.
Each row element in the listView will contain 3 textViews - RSSFeedName, publishDate & feedLength
The contents of the feeds is retrived from a HTTPRsponse.
I'm fetching this response in an AsyncTask.
So, in the doInBackground(), I've send the HTTPRequest & received & parsed the response & prepared the ArrayList containing 3 above mentioned information.
Then inside the doInBackground() only, I'm creating the customized ArrayAdapter for forming the 3 TextViews in row element.
My intetions are to set this adapter on ListView in onPostExecute().
But, when I run the application, the ListView does not display anything.
I tried to debug & it seems like getView() in the ArrayAdapter class is not getting called. (But I'm not sure if this is the reason).
Here is the code, sorry for the length...it seemed necessary.
Activity Code:
public class GenericFeedsActivity extends Activity{
private ListView lvFeedsList;
private ArrayList<FeedsClass> feedList;
protected void onCreate(Bundle savedInstanceState) {
...
lvFeedsList = (ListView) findViewById(R.id.lvFeedsList);
lvFeedsList.setOnItemClickListener(this);
lvFeedsList.setEnabled(false);
...
new AsyncResponseHandler(this).execute();
}
class AsyncResponseHandler extends AsyncTask {
Context context;
FeedListAdapter adapter;
public AsyncResponseHandler(Context c) {
this.context = c;
}
#Override
protected Object doInBackground(Object... params) {
...
/*
* Sending HTTPRequest to a URL & getting list of feeds
* Saving this list of feeds in a ArrayList -feedList, containing elements of type FeedsClass (declared above)
* Below line parses the HTTPResponse XML & stores various information in feedList.
*/
feedList = utils.parseRssResponseXML(in); // Working fine, geeting elements
adapter = new FeedListAdapter(
GenericFeedsActivity.this, feedList);
in.close();
return null;
}
protected void onPostExecute(Object e) {
// Setting Arrayadapter
lvFeedsList.setAdapter(adapter);
lvFeedsList.setEnabled(true);
}
}
}
Adapter Code:
public class FeedListAdapter extends ArrayAdapter {
private Context context;
private ArrayList<FeedsClass> feedList;
public FeedListAdapter(Context c, ArrayList<FeedsClass> data) {
super(c, R.layout.rowlayout);
this.context = c;
this.feedList = data;
}
class ViewHolder {
TextView tvFeedName;
TextView tvFeedPubDate;
TextView tvFeedLength;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
View row = convertView;
ViewHolder holder = null;
if (row == null) {
LayoutInflater inflator = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
row = inflator.inflate(R.layout.rowlayout, null);
holder = new ViewHolder();
holder.tvFeedName = (TextView) row.findViewById(R.id.tvFeedName);
holder.tvFeedPubDate = (TextView) row.findViewById(R.id.tvFeedPubDate);
holder.tvFeedLength = (TextView) row.findViewById(R.id.tvFeedLength);
row.setTag(holder);
} else {
holder = (ViewHolder) row.getTag();
}
// Getting values of feedName, publishDate & feedLength
String feedName = feedList.get(position).getTitle();
String feedDate = feedList.get(position).getPublishDate();
String feedLength = feedList.get(position).getStreamLength();
holder.tvFeedName.setText(feedName);
holder.tvFeedPubDate.setText(feedDate);
holder.tvFeedLength.setText(feedLength);
}
return row;
}
}
The issue is that you are subclassing ArrayAdapter. This doesn't work because ArrayAdapter internally thinks you do not have any elements in your data; it doesn't just magically know to look in the lvFeedsList variable because the data set it uses is internal.
Instead, in your constructor make sure to call this constructor instead:
Adapter code:
public FeedListAdapter(Context c, ArrayList<FeedsClass> data) {
super(c, R.layout.rowlayout, data); // add 'data'
this.context = c;
this.feedList = data;
}
Which will make everything work correctly.
adapter.notifyDataSetChanged()
could help at the end on of AsyncResponseHandler.onPostExecute(). If not - check whether ArrayList which hold data for adapter is empty or not.