Develop Reference

Android - Listview adapter with asynctask to load images

I'm trying to handle an image loading at the background.
Now, I've look at the next link - here
And I've got few things I don't understand -
1) I've made the next CursorAdapter for the listview items-
public class ChatCursorAdapter extends CursorAdapter implements OnClickListener {
public ChatCursorAdapter(Context context, Cursor c) {
super(context, c, 0);
}
#Override
public int getCount() {
return getCursor() == null ? 0 : super.getCount();
}
#Override
public int getViewTypeCount() {
return 2;
}
#Override
public int getItemViewType(int _position) {
Cursor cursor = (Cursor) getItem(_position);
return getItemViewType(cursor);
}
private int getItemViewType(Cursor cursor) {
String sender = cursor.getString(2);
SharedPreferences userPref = PreferenceManager
.getDefaultSharedPreferences(MainChat.this);
String saveUser = userPref.getString("user", "");
if (saveUser.equalsIgnoreCase(sender)){
return 0;
}else{
return 1;
}
}
#Override
public void bindView(View view, Context context, Cursor cursor) {
holder = (ViewHolder) view.getTag();
holder.mesg.setText(getSmiledText(MainChat.this,msg));
holder.mesg2.setText(getSmiledText(MainChat.this,msg2));
holder.myImage.setTag(picPath);
holder.myImage.setImageBitmap(setImageToImageView(picPath));
}
#Override
public View newView(Context context, Cursor cursor, ViewGroup parent) {
ViewHolder holder = new ViewHolder();
View itemLayout = null;
switch(getItemViewType(cursor)){
case 0:
itemLayout = getLayoutInflater().inflate(R.layout.msg_item1,parent, false);
break;
case 1:
itemLayout = getLayoutInflater().inflate(R.layout.msg_item13, parent,false);
break;
}
itemLayout.setTag(holder);
holder.mesg = (TextView) itemLayout.findViewById(R.id.text_start);
holder.mesg2 = (TextView) itemLayout.findViewById(R.id.text_end);
holder.myImage = (ImageView) itemLayout.findViewById(R.id.imageView_msgpic);
return itemLayout;
}
Now i wnat to use the info from the link.
But i don't understand - What i need to pass into the and what to AsyncTask leave at CursorAdapter?
Also the sample code uses -
.execute(holder);
Can't I call to the AsyncTask like this -
new AsyncTask().execute();
And how and where should i call the AsyncTask, I don't understand it?
Thanks for any kind of help

You could always use an external lib like Universal-Image-Loader or Picasso to achieve what you are trying to do =)

Take a look at AsyncTask. You must Override doInBackground method. You may define a constructor to supply view in which you want to put downloaded image.
public class ImageDownloader extends AsyncTask<String, Void, List<Bitmap>> {
private ImageView ivImageHolder;
private Context context;
public ImageDownloader(Context context, ImageView imageHolder) {
this.ivImageHolder = imageHolder;
this.context = context;
}
...
#Override
protected List<Bitmap> doInBackground(String... params) {
//This happens in background
List<Bitmap> bitmaps = new ArrayList<Bitmap>();
for (String url : params) {
Bitmap bitmap = DownloadImage(url);
bitmaps.add(bitmap);
}
return bitmaps;
}
....
private Bitmap DownloadImage(String URL) {
Bitmap bitmap = null;
InputStream in = null;
try {
in = OpenHttpConnection(URL);
bitmap = BitmapFactory.decodeStream(in);
in.close();
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
return bitmap;
}
...
private InputStream OpenHttpConnection(String urlString) throws IOException {
InputStream in = null;
int response = -1;
URL url = new URL(urlString);
URLConnection conn = url.openConnection();
if (!(conn instanceof HttpURLConnection))
throw new IOException("Not an HTTP connection");
try {
HttpURLConnection httpConn = (HttpURLConnection) conn;
httpConn.setAllowUserInteraction(false);
httpConn.setInstanceFollowRedirects(true);
httpConn.setRequestMethod("GET");
httpConn.connect();
response = httpConn.getResponseCode();
if (response == HttpURLConnection.HTTP_OK) {
in = httpConn.getInputStream();
}
} catch (Exception ex) {
throw new IOException("Error connecting");
}
return in;
}
#Override
protected void onPostExecute(List<Bitmap> bitmaps) {
super.onPostExecute(bitmaps);
for (int i = 0; i < bitmaps.size(); i++) {
final Bitmap bitmap = bitmaps.get(i);
ivImageHolder.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
new ImageViewActivity(context, bitmap).show();
}
});
// iv.setImageBitmap(bitmap);
ivImageHolder.setImageBitmap(bitmap);
ivImageHolder.setVisibility(ImageView.VISIBLE);
}
}

if you write your asyntask method I can say how can you use it, If it need to string value
you can use like this:
new your_async(context).execute(url) ;
But in my advice : you should use lazyadapter to use bitmaps on listview because there is a mermory issue if you do not pay attention properties of images.
here is link : stackoverfow

image display as gridview

i want to display images from mysql server(testing in localhost) using imageurl,i have images in a filder on my server,in an android client app as gridview along with text.how do i use imageurl in my code?
mymainmenu.java
public class MainMenu extends Activity {
GridView gridView;
static final String[] MOBILE_OS = new String[] {
"Android", "iOS","Windows", "Blackberry" };
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.mainmenu_list);
gridView = (GridView) findViewById(R.id.gridView1);
gridView.setAdapter(new ImageAdapter(this, MOBILE_OS));
gridView.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View v,
int position, long id) {
Toast.makeText(
getApplicationContext(),
((TextView) v.findViewById(R.id.grid_item_label))
.getText(), Toast.LENGTH_SHORT).show();
}
});
}
}
my imageadapter.java:
public class ImageAdapter extends BaseAdapter {
private Context context;
private final String[] mobileValues;
public ImageAdapter(Context context, String[] mobileValues) {
this.context = context;
this.mobileValues = mobileValues;
}
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View gridView;
if (convertView == null) {
gridView = new View(context);
// get layout from list.xml
gridView = inflater.inflate(R.layout.list, null);
// set value into textview
TextView textView = (TextView) gridView
.findViewById(R.id.grid_item_label);
textView.setText(mobileValues[position]);
// set image based on selected text
ImageView imageView = (ImageView) gridView
.findViewById(R.id.grid_item_image);
String mobile = mobileValues[position];
if (mobile.equals("Windows")) {
imageView.setImageResource(R.drawable.imggrid);
} else if (mobile.equals("iOS")) {
imageView.setImageResource(R.drawable.imggrid);
} else if (mobile.equals("Blackberry")) {
imageView.setImageResource(R.drawable.imggrid);
} else {
imageView.setImageResource(R.drawable.imggrid);
}
} else {
gridView = (View) convertView;
}
return gridView;
}
#Override
public int getCount() {
return mobileValues.length;
}
#Override
public Object getItem(int position) {
return null;
}
#Override
public long getItemId(int position) {
return 0;
}
}
I dnt know how to use the following in my code:
try {
URL url = new URL(imageFileURL);
URLConnection conn = url.openConnection();
HttpURLConnection httpConn = (HttpURLConnection)conn;
httpConn.setRequestMethod("GET");
httpConn.connect();
if (httpConn.getResponseCode() == HttpURLConnection.HTTP_OK) {
InputStream inputStream = httpConn.getInputStream();
Bitmap bitmap = BitmapFactory.decodeStream(inputStream);
inputStream.close();
img.setImageBitmap(bitmap);
}
} catch (MalformedURLException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

Put the image downloading code in a AsyncTask. Here is the explanation.
Execute one instance of asynctask in your getView method, i.e to fetch one image everytime.
private class DownloadImageTask extends AsyncTask<String, Void, Bitmap> {
ImageView mImageView;
public void setImageView(ImageView img) {
mImageView = img;
}
protected Bitmap doInBackground(String... urls) {
return loadImageFromNetwork(urls[0]);
}
protected void onPostExecute(Bitmap result) {
mImageView.setImageBitmap(result);
}
}
Call task.setImageView(yourImageViewinGrid) before executing your AsyncTask to let it know where to set the image after downloading.

To get the image, you have to do something like :
URL new_url = new URL("your url");
Bitmap image_bitmap = BitmapFactory.decodeStream(newurl.openConnection() .getInputStream()); ImageView image_view = new ImageView(this);
image_view.setImageBitmap(image_bitmap);
Anyway, it's better to download the image as background task. What I actually do is to create a custom view with one private inner class that extend AsyncTask to download the image for you.

I dnt know how to use the following in my code:
that code will download the image for you, you can place in separate thread either AsyncTask or Thread and set the downloaded image in the imageview... simple as that. There are so many example on the web you can google it out
EIDTED
code to download the image
public class AsyncFetchImage extends AsyncTask<String, Void, Bitmap>{
private WeakReference<ImageView> imageReference;
// private WeakReference<Dialog> dialogReferance;
public AsyncFetchImage(ImageView imageview) {
imageReference = new WeakReference<ImageView>(imageview);
// dialogReferance = new WeakReference<Dialog>(dialog);
}
#Override
protected Bitmap doInBackground(String... s) {
return downloadImage(s[0]);
}
private Bitmap downloadImage(String url) {
final AndroidHttpClient client = AndroidHttpClient.newInstance("Nixit");
final HttpGet getRequest = new HttpGet(url);
try {
HttpResponse response = client.execute(getRequest);
final int statusCode = response.getStatusLine().getStatusCode();
if(statusCode != HttpStatus.SC_OK){
Log.w("ImageDownloader", "Error " + statusCode + " while retrieving bitmap from " + url);
return null;
}
final HttpEntity entity = response.getEntity();
if(entity != null){
InputStream is = null;
try{
is = entity.getContent();
final Bitmap bit = BitmapFactory.decodeStream(is);
return bit;
}finally{
if(is != null)
is.close();
entity.consumeContent();
}
}
} catch (IOException e) {
e.printStackTrace();
return null;
} finally{
if(client != null){
client.close();
}
}
Log.i("Image Fetch","Image Fetch Complete");
return null;
}
#Override
protected void onPostExecute(Bitmap result) {
if(isCancelled()){
result = null;
}
if(imageReference != null){
ImageView imageView = imageReference.get();
// Dialog di = dialogReferance.get();
if (imageView != null) {
imageView.setImageBitmap(result);
// di.show();
}
}
}
}
How to use:-
imageView = (ImageView)dialog.findViewById(R.id.imageView1);
AsyncFetchImage fetchImage = new AsyncFetchImage(imageView);
fetchImage.execute(url);
You can use this in getview method of adapter
Hope that help

Android - GridView's onResume

I am developing Android apps,
once part of this apps is creating a GridView that contain some image (the image is loaded from URL),
then another activity that show the selected image in full screen will be appeared when one of image in GridView is onClick.
Problem:
When I enter the GridView activity, it takes some second to load all image in gridview normally.
Then I click one of image to enter the full screen activity and click back button to go back to GridView,
but, it takes some second to loading when go back to gridview, just like loading all image again.
I wonder why the gridview activity will loading for a few second when onResume?
For example, in Google Play, the full screen view of sample image in any apps can be back to previous view immediately.
Enclosed code:
GridView:
public class ManagePhoto extends Activity {
ImageAdapter ia;
GridView gridview;
InputStream inputStream;
private static final int SELECT_PICTURE = 1;
private String selectedImagePath;
TextView tvRunningMark;
boolean bRunning;
String[] purl;
Bitmap[] bm;
String the_string_response;
TouchImageView touch;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.photo_manage);
//gv is Gobal Value
final Gvalue gv = ((Gvalue) getApplicationContext());
gridview = (GridView) findViewById(R.id.gv_photo);
gridview.setOnItemClickListener(new GridView.OnItemClickListener() {
public void onItemClick(AdapterView adapterView, View view,int position, long id) {
gv.setbm(bm[position]);
Intent myIntent = new Intent(adapterView.getContext(), FullScreenImage.class);
startActivityForResult(myIntent, 0);
}
});
new GridTask().execute();
}
public class ImageAdapter extends BaseAdapter {
private Context mContext;
public ImageAdapter(Context c) {
mContext = c;
}
public int getCount() {
return purl.length;
}
public Object getItem(int position) {
return null;
}
public long getItemId(int position) {
return 0;
}
// create a new ImageView for each item referenced by the Adapter
public View getView(int position, View convertView, ViewGroup parent) {
ImageView imageView;
if (convertView == null) { // if it's not recycled, initialize some
// attributes
imageView = new ImageView(mContext);
imageView.setLayoutParams(new GridView.LayoutParams(200,200));
imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
imageView.setPadding(8, 8, 8, 8);
} else {
imageView = (ImageView) convertView;
}
try {
bm[position] = loadBitmap(purl[position]);
imageView.setImageBitmap(bm[position]);
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return imageView;
}
}
class GridTask extends AsyncTask<Void, String, Void> {
#Override
protected void onPostExecute(Void result) {
gridview.setAdapter(ia);
final LinearLayout llo_probar = (LinearLayout)findViewById(R.id.llo_probar);
llo_probar.setVisibility(LinearLayout.GONE);
gridview.setVisibility(GridView.VISIBLE);
}
#Override
protected void onPreExecute() {
}
#Override
protected void onProgressUpdate(String... values) {
}
#Override
protected Void doInBackground(Void... params) {
getphoto();
bm = new Bitmap[purl.length];
ia = new ImageAdapter(ManagePhoto.this);
return null;
}
}
private Bitmap loadBitmap(String url) throws MalformedURLException,IOException {
return BitmapFactory.decodeStream(new FlushedInputStream(
(InputStream) new URL(url).getContent()));
}
class FlushedInputStream extends FilterInputStream {
public FlushedInputStream(final InputStream inputStream) {
super(inputStream);
}
#Override
public long skip(final long n) throws IOException {
long totalBytesSkipped = 0L;
while (totalBytesSkipped < n) {
long bytesSkipped = in.skip(n - totalBytesSkipped);
if (bytesSkipped == 0L) {
int bytesRead = read();
if (bytesRead < 0) { // we reached EOF
break;
}
bytesSkipped = 1;
}
totalBytesSkipped += bytesSkipped;
}
return totalBytesSkipped;
}
}
public void getphoto(){
final Gvalue gv = ((Gvalue) getApplicationContext());
final TextView tv_fn = (TextView) findViewById(R.id.tv_fn);
String result = "";
ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
nameValuePairs.add(new BasicNameValuePair("sql",
("select * from personal_photo where member_id = " + gv.getuid())));
InputStream is = null;
// http post
try {
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost("http://" + gv.getserverIP()
+ "/android_getdata.php");
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
is = entity.getContent();
} catch (Exception e) {
Log.e("log_tag", "Error in http connection " + e.toString());
}
// convert response to string
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(
is, "iso-8859-1"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
result = sb.toString();
} catch (Exception e) {
Log.e("log_tag", "Error converting result " + e.toString());
}
// parse json data
try {
List url = new ArrayList();
JSONArray jArray = new JSONArray(result);
for (int i = 0; i < jArray.length(); i++) {
JSONObject json_data = jArray.getJSONObject(i);
url.add(json_data.getString("save_location"));
}
int size = url.size();
purl = new String[size];
for (int j = 0; j < size; j++) {
purl[j] = (String) url.get(j);
}
} catch (JSONException e) {
Log.e("log_tag", "Error parsing data " + e.toString());
}
}
public void toast(String text) {
Toast.makeText(ManagePhoto.this, text, 5).show();
}
}
Full screen:
public class FullScreenImage extends Activity {
TouchImageView touch;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);
requestWindowFeature(Window.FEATURE_NO_TITLE);
new ShowPhotoTask().execute();
}
class ShowPhotoTask extends AsyncTask<Void, String, Void> {
#Override
protected void onPostExecute(Void result) {
setContentView(touch);
}
#Override
protected void onPreExecute() {
setContentView(R.layout.full_image);
}
#Override
protected void onProgressUpdate(String... values) {
}
#Override
protected Void doInBackground(Void... params) {
final Gvalue gv = ((Gvalue) getApplicationContext());
touch = new TouchImageView(FullScreenImage.this);
touch.setMaxZoom(4f); // change the max level of zoom, default is 3f
touch.setImageBitmap(gv.getbm());
return null;
}
}
}

From your getView code in your ImageAdapter, everytime you will load the image from the internet again.
You should download the image to local, next time, when your set the image, you try to get it from local firstly.
As well you should put the get bitmap in the thread as you have putting the parse JSON in the thread.
Here is an demo, i think it will help you.

In your gridview onclick you are starting activity with startActivityForResults(intent,0); replace it with startActivity(intent);
also when you are finishing the FullScreenActivity just use finish();
might solve your problem

It's so slow because you don't perform your operations with background threads, caching..
A simple and better solution could be a collection that contains all your bitmaps inserted by AsyncTasks that you'll execute to download the pictures.
There are better solutions but they are more difficult to implement.
For example you can consider the possibility to keep a thread pool that resolves your runnables represented by "download the http://jhon.doe.jpg" and then "show now on the UI thread".

As you have written below function inside the getView() method:
bm[position] = loadBitmap(purl[position]);
I would say you should implement code to load Image Asynchronously. In this logic, image is synced in your memory card once its downloading is done. So next time it will load directly from memory card instead of loading it from web again.
Here is a code example you can give a try: Android - Universal Image Loader

android:load images from url and show in gridview

i am making an app in which i have to get response from xml and i get image urls .Now i want to put images from urls into gridview but i dnt know how to extract images from urls and put in gridview.Any help will be appreciated.My code is as follows:
public class GalleryNewActivity extends Activity {
private ProgressDialog dialog;
GridView ga;
Element e;
Node elem;
public List<Drawable> pictures;
ImageView imageView;
static final String PREFS_NAME = "MyPrefs";
static final String USER_KEY = "user";
static final String Name = "name";
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
if(isNetworkconn()){
new GetSPCAsyncTask().execute("");
}else{
showDialogOnNoInternet();
}
ga = (GridView)findViewById(R.id.Gallery01);
ga.setAdapter(new ImageAdapter(this));
imageView = (ImageView)findViewById(R.id.ImageView01);
}
public class ImageAdapter extends BaseAdapter {
private Context mContext;
public ImageAdapter(Context c) {
mContext = c;
}
public int getCount() {
return pictures.size();
}
public Object getItem(int position) {
return null;
}
public long getItemId(int position) {
return 0;
}
// create a new ImageView for each item referenced by the Adapter
public View getView(int position, View convertView, ViewGroup parent) {
View v;
if (convertView == null) { // if it's not recycled, initialize some
// attributes
LayoutInflater li = getLayoutInflater();
v = li.inflate(R.layout.galleryitem, null);
imageView = (ImageView)v.findViewById(R.id.thumbImage);
imageView.setLayoutParams(new GridView.LayoutParams(200, 250));
// imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
imageView.setPadding(2, 5, 2, 5);
} else {
imageView = (ImageView) convertView;
}
imageView.setImageDrawable(pictures.get(position));
imageView.setTag(pics[position]);
return imageView;
}
private class GetPicsToNextPage extends AsyncTask<String, String, String>{
#Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
dialog = ProgressDialog.show(GalleryNewActivity.this, "Please wait", "Loading...");
}
#Override
protected String doInBackground(String... params) {
// TODO Auto-generated method stub
String str = null;
try {
Thread.sleep(2000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return str;
}
#Override
protected void onPostExecute(String result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
dialog.dismiss();
Intent intent = new Intent(getApplicationContext(), Flip3d.class);
startActivity(intent);
}
}
private boolean isNetworkconn(){
ConnectivityManager conMgr = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
if (conMgr.getActiveNetworkInfo() != null && conMgr.getActiveNetworkInfo().isAvailable() && conMgr.getActiveNetworkInfo().isConnected()) {
return true;
}else{
return false;
}
}
private void showDialogOnNoInternet(){
AlertDialog.Builder alt_bld = new AlertDialog.Builder(GalleryNewActivity.this);
alt_bld.setTitle("Error.");
alt_bld.setMessage("Your phone is not connected to internet.");
alt_bld.setCancelable(false);
alt_bld.setNeutralButton("OK", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
// TODO Auto-generated method stub
dialog.dismiss();
}
});
alt_bld.show();
}
//loader for dynamic starts
private class GetSPCAsyncTask extends AsyncTask<String, String, String>{
#Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
dialog = ProgressDialog.show(GalleryNewActivity.this, "Please wait", "Loading...");
}
#Override
protected String doInBackground(String... params) {
// TODO Auto-generated method stub
ArrayList<HashMap<String, String>> mylist = new ArrayList<HashMap<String, String>>();
String xml = XMLfunctions.getXML();
Document doc = XMLfunctions.XMLfromString(xml);
NodeList nodes = doc.getElementsByTagName("Image");
for (int i = 0; i < nodes.getLength(); i++) {
HashMap<String, String> map = new HashMap<String, String>();
e = (Element)nodes.item(i);
//map.put("Image", XMLfunctions.getValue(e, "Image"));
map.put("ImagePath", "Naam:" + XMLfunctions.getValue(e, "ImagePath"));
map.put("ImageHeadline", "Headline: " + XMLfunctions.getValue(e, "ImageHeadline"));
System.out.println(map.put("ImageHeadline", "Headline: " + XMLfunctions.getValue(e, "ImageHeadline")));
map.put("ImageDesc", "Desc: " + XMLfunctions.getValue(e, "ImageDesc"));
System.out.println(map.put("ImageDesc", "Desc: " + XMLfunctions.getValue(e, "ImageDesc")));
mylist.add(map);
Drawable d=LoadImageFromWebOperations();
pictures.add(d);
}
return xml;}
#Override
protected void onPostExecute(String result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
dialog.dismiss();
}
private Drawable LoadImageFromWebOperations()
{
String path=XMLfunctions.getValue(e, "ImagePath");
try{
InputStream is = (InputStream) new URL(path).getContent();
Drawable d = Drawable.createFromStream(is, "src name");
Log.w("CREADO","CREADO");
return d;
}catch (Exception e) {
System.out.println("Exc="+e);
return null;
}
}
}
}

I would suggest you to check below solutions for loading images from URL:
Android - Universal Image loader by Nostra
Lazy load of images in ListView
Result you can get if you use Universal image loader:

call this function with url you will get Drawable , and then store this drawables into custom class and then place in grid view.
call function like this
ImageOperations(this, imageurl)
public Object fetch(String address) throws MalformedURLException, IOException {
URL url = new URL(address);
Object content = url.getContent();
return content;
}
private Drawable ImageOperations(Context ctx, String url) {
try {
InputStream is = (InputStream) this.fetch(url);
Drawable d = Drawable.createFromStream(is, "src");
return d;
} catch (MalformedURLException e) {
return null;
} catch (IOException e) {
return null;
}
}

https://github.com/koush/UrlImageViewHelper
UrlImageViewHelper will fill an ImageView with an image that is found at a URL.
The sample will do a Google Image Search and load/show the results asynchronously.
UrlImageViewHelper will automatically download, save, and cache all the image urls the BitmapDrawables. Duplicate urls will not be loaded into memory twice. Bitmap memory is managed by using a weak reference hash table, so as soon as the image is no longer used by you, it will be garbage collected automatically.
else use this,
public static Bitmap loadBitmap(String url) {
Bitmap bitmap = null;
InputStream in = null;
BufferedOutputStream out = null;
try {
in = new BufferedInputStream(new URL(url).openStream(), IO_BUFFER_SIZE);
final ByteArrayOutputStream dataStream = new ByteArrayOutputStream();
out = new BufferedOutputStream(dataStream, IO_BUFFER_SIZE);
copy(in, out);
out.flush();
final byte[] data = dataStream.toByteArray();
BitmapFactory.Options options = new BitmapFactory.Options();
//options.inSampleSize = 1;
bitmap = BitmapFactory.decodeByteArray(data, 0, data.length,options);
} catch (IOException e) {
Log.e(TAG, "Could not load Bitmap from: " + url);
} finally {
closeStream(in);
closeStream(out);
}
return bitmap;
}

FATAL Exception main while displaying images in listview

I am at beginner level, i am populating listview with different remote images and text in an android app. I am using adapter to populate listview and AsynTask to load images. But i am facing two problems and tried most since many days but unfortunately can't success. First problem is that first image and text appears in first row of listview and disappears than second row being populated with second image and text and also disappears and similarly each rows appears with images and text and disappears. Second problem is that when final row appears than app crashes and stopped running giving below exception:
11-01 20:03:56.449: ERROR/AndroidRuntime(29665): FATAL EXCEPTION: main
11-01 20:03:56.449: ERROR/AndroidRuntime(29665): java.lang.NullPointerException
This is my main class:
public class ParseImagesActivity extends ListActivity {
String myURL;
String xml;
Document doc;
NodeList nodes;
//int i=5;
int j=0;
int equal;
int h;
String[] length = {"1","2","3","4","5","6","7","8","9",null};
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//setContentView(R.layout.main);
xml = XmlParser.getXML("http://url.com");
doc = XmlParser.XMLfromString(xml);
nodes = doc.getElementsByTagName("item");
Element g = (Element)nodes.item(j);
startParsing(XmlParser.getValue(g,"thumb"));
}
In main class i am calling startParsing method passing it a url..1 to access first image by function XmlParser.getValue(g,"thumb") which return url from XmlParser class. startParsing method is:
private void startParsing(String url) {
new backgroundLoadListView().execute(url);
}
public class backgroundLoadListView extends
AsyncTask<String, Void, String> {
#Override
protected void onPostExecute(String unused) {
// TODO Auto-generated method stub
if(j<nodes.getLength()){
setListAdapter(new MyCustomAdapter(ParseImagesActivity.this, R.layout.row, length));
Log.e("post Execute","post execute="+j);
equal=j;
j++;
Element h = (Element)nodes.item(j);
startParsing(XmlParser.getValue(h,"thumb"));
}
}
#Override
protected void onPreExecute() {
}
#Override
protected String doInBackground(String... params) {
// TODO Auto-generated method stub
//Log.e("do in back","do in back="+j);
String url = params[0];
preLoadSrcBitmap(url);
return null;
}
}
Here i am calling MyCustomerAdapter constructor and in postExecute method i am calling startParsing method passing url2,3,4,...etc to access other images. MyCustomAdapter class and preloadSrcBitmap method are:
public class MyCustomAdapter extends ArrayAdapter<String> {
Bitmap bm;
public MyCustomAdapter(Context context, int textViewResourceId,
String[] objects) {
//
super(context, textViewResourceId, objects);
// TODO Auto-generated constructor stub
bm = srcBitmap;
Log.e("my customer adapter","my adapter"+j);
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
//return super.getView(position, convertView, parent);
View row = convertView;
if(row==null){
LayoutInflater inflater=getLayoutInflater();
row=inflater.inflate(R.layout.row, parent, false);
}
Log.e("getview",j+"calls");
TextView label=(TextView)row.findViewById(R.id.weekofday);
ImageView icon=(ImageView)row.findViewById(R.id.icon);
if(j<nodes.getLength())
{
if(equal==position)
{
Log.e("text view calls",""+equal);
Element f = (Element)nodes.item(equal);
label.setText(XmlParser.getValue(f, "title"));
icon.setImageBitmap(bm);
}
}
return row;
}
}
Bitmap srcBitmap;
private void preLoadSrcBitmap(String url){
//Log.e("preloadsrcbitmap","preloadsrcbitmap="+j);
BitmapFactory.Options bmOptions;
bmOptions = new BitmapFactory.Options();
bmOptions.inSampleSize = 1;
srcBitmap = LoadImage(url, bmOptions);
}
/** Called when the activity is first created. */
#Override
protected void onListItemClick(ListView l, View v, int position, long id) {
String selection = l.getItemAtPosition(position).toString();
Toast.makeText(this, selection, Toast.LENGTH_LONG).show();
}
private Bitmap LoadImage(String URL, BitmapFactory.Options options)
{
Bitmap bitmap = null;
InputStream in = null;
try {
in = OpenHttpConnection(URL);
bitmap = BitmapFactory.decodeStream(in, null, options);
in.close();
} catch (IOException e1) {
}
return bitmap;
}
private InputStream OpenHttpConnection(String strURL) throws IOException{
InputStream inputStream = null;
URL url = new URL(strURL);
URLConnection conn = url.openConnection();
try{
HttpURLConnection httpConn = (HttpURLConnection)conn;
httpConn.setRequestMethod("GET");
httpConn.connect();
if (httpConn.getResponseCode() == HttpURLConnection.HTTP_OK) {
inputStream = httpConn.getInputStream();
}
}
catch (Exception ex){
}
return inputStream;
}
And thanks very much to the peoples helping me with mentioned problems. I can't figure them out.

Anything that updates the UI (interacts with the Activity) with an AsyncTask needs to have the following structure (outline because I haven't done this in awhile :P):
//AsyncTask starts here
//code that doesn't run on the UI thread
myASyncTask.runOnUiThread(new Runnable() {
//update your UI stuff here
};
//do more non-UI stuff here
It looks like you're trying to update ImageViews and TextViews synchronously within an AsyncTask method. This will cause Fatal Errors. Try the code above :)
Hope this helps! Let me know if you need more clarification.
Thanks