Develop Reference

What is the right coding about Image Loading?

I'm solving my problem about Image Loader and I have some problems..
What I want is to show many images (about 400) in GridView(or ListView).
I don't want to use the Library like Picasso, Glide like that.
and Here is the problem.
When I call the method which convert from url to bitmap?
3.1. before setAdapter, then pass the bitmap array.
3.2. while getView.
two things are working well. but too much slow... maybe cuz of the times to call URLConnection..
Could anyone help me about these problem? How can I speed up? or are there any other solution without Open Source.
Here is my Source.
Now, 3-1.
ShowImage
private void showImages(ArrayList<String> imgUrls) {
ArrayList<Bitmap> bitmaps = new ArrayList<>();
for (int i = 0; i < imgUrls.size(); i++) {
try {
String img_path = imgUrls.get(i);
Bitmap bitmap = new UriToBitmapAsyncTask().execute(img_path).get();
bitmaps.add(bitmap);
} catch (Exception e) {
Toast.makeText(this, e.getMessage(), Toast.LENGTH_SHORT).show();
}
}
CustomAdapter adapter = new CustomAdapter(getApplicationContext(),R.layout.row,bitmaps);
gridView.setAdapter(adapter);
}
and This is the customAdapter's GetView
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder viewHolder;
if (convertView == null) {
convertView = inflator.inflate(rowLayout, parent, false);
viewHolder = new ViewHolder();
viewHolder.imageView = (ImageView) convertView.findViewById(R.id.imageView);
convertView.setTag(viewHolder);
} else {
viewHolder = (ViewHolder) convertView.getTag();
}
viewHolder.imageView.setImageBitmap(bitmaps.get(position));
return convertView;
}

You should really take Reinventing the wheel to heart but if you really want to toture yourself an Approach could be:
use a ThreadPoolExecutor to fetch more images at once, you should read up how to use them
implement a way to cancel threads who load a img for a griditem which isn't displayed anymore
use two sets of data a thumbnail which loads faster for the grid view and a real image which gets loaded when the user clicks on the grid
dont't forget to use a LRU caching method or your device will run out of memory depending on the images

Don't use ArrayList to store bitmaps. Bitmaps usually take consumes a lot of memory. Try using LRUCache like this way,
public class TCImageLoader implements ComponentCallbacks2 {
private TCLruCache cache;
public TCImageLoader(Context context) {
ActivityManager am = (ActivityManager) context.getSystemService(
Context.ACTIVITY_SERVICE);
int maxKb = am.getMemoryClass() * 1024;
int limitKb = maxKb / 8; // 1/8th of total ram
cache = new TCLruCache(limitKb);
}
public void display(String url, ImageView imageview, int defaultresource) {
imageview.setImageResource(defaultresource);
Bitmap image = cache.get(url);
if (image != null) {
imageview.setImageBitmap(image);
}
else {
new SetImageTask(imageview).execute(url);
}
}
private class TCLruCache extends LruCache<String, Bitmap> {
public TCLruCache(int maxSize) {
super(maxSize);
}
#Override
protected int sizeOf(ImagePoolKey key, Bitmap value) {
int kbOfBitmap = value.getByteCount() / 1024;
return kbOfBitmap;
}
}
private class SetImageTask extends AsyncTask<String, Void, Integer> {
private ImageView imageview;
private Bitmap bmp;
public SetImageTask(ImageView imageview) {
this.imageview = imageview;
}
#Override
protected Integer doInBackground(String... params) {
String url = params[0];
try {
bmp = getBitmapFromURL(url);
if (bmp != null) {
cache.put(url, bmp);
}
else {
return 0;
}
} catch (Exception e) {
e.printStackTrace();
return 0;
}
return 1;
}
#Override
protected void onPostExecute(Integer result) {
if (result == 1) {
imageview.setImageBitmap(bmp);
}
super.onPostExecute(result);
}
private Bitmap getBitmapFromURL(String src) {
try {
URL url = new URL(src);
HttpURLConnection connection
= (HttpURLConnection) url.openConnection();
connection.setDoInput(true);
connection.connect();
InputStream input = connection.getInputStream();
Bitmap myBitmap = BitmapFactory.decodeStream(input);
return myBitmap;
} catch (IOException e) {
e.printStackTrace();
return null;
}
}
}
#Override
public void onConfigurationChanged(Configuration newConfig) {
}
#Override
public void onLowMemory() {
}
#Override
public void onTrimMemory(int level) {
if (level >= TRIM_MEMORY_MODERATE) {
cache.evictAll();
}
else if (level >= TRIM_MEMORY_BACKGROUND) {
cache.trimToSize(cache.size() / 2);
}
}
}
get a instance of TCImageLoader and call display method appropriately.

Nothing getting displayed in singleitem view

I am having an app that retrieves information from parse and display into a list view ,but when the app is run and the list view item is clicked it opens a new activity and display some images and text from parse.com but it shows nothing like the image below
Here is my code
main activity.java
public class MainActivity extends Activity
{
ListView listview;
List<ParseObject> ob;
ProgressDialog mProgressDialog;
FinalAdapter adapter;
private List<CodeList> codelist = null;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.beg_layout);
new RemoteDataTask().execute();
}
private class RemoteDataTask extends AsyncTask<Void, Void, Void>
{
#Override
protected void onPreExecute() {
super.onPreExecute();
// Create a progressdialog
mProgressDialog = new ProgressDialog(MainActivity.this);
// Set progressdialog title
mProgressDialog.setTitle("Testing");
// Set progressdialog message
mProgressDialog.setMessage("Loading. Please wait this may take few moments ....");
mProgressDialog.setIndeterminate(true);
// Show progressdialog
mProgressDialog.show();
}
#Override
protected Void doInBackground(Void... params)
{
codelist = new ArrayList<CodeList>();
try{
ParseQuery<ParseObject> query = new ParseQuery<ParseObject>(
"BeginnerActivity");
query.orderByAscending("_created_at");
ob = query.find();
for(ParseObject begactivity : ob){
ParseFile listimg = (ParseFile) begactivity.get("alphabetimg");
ParseFile levelimg = (ParseFile) begactivity.get("levelimg");
ParseFile apiimg = (ParseFile) begactivity.get("apiimg");
ParseFile descimgone = (ParseFile) begactivity.get("descimgone");
ParseFile descimgtwo = (ParseFile) begactivity.get("descimgtwo");
CodeList map = new CodeList();
map.setListHeading((String) begactivity.get("listheading"));
map.setSingleItemHeading((String) begactivity.get("heading"));
map.setDescription((String) begactivity.get("subheading"));
map.setApiText((String) begactivity.get("apitext"));
map.setFinalCodeText((String) begactivity.get("codetext"));
map.setAlphabetimg(listimg.getUrl());
map.setLevelImg(levelimg.getUrl());
map.setApiImg(apiimg.getUrl());
map.setPreviewImgOne(descimgone.getUrl());
map.setPreviewImgTwo(descimgtwo.getUrl());
codelist.add(map);
}
}catch(ParseException e){
Log.e("Error", e.getMessage());
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(Void result) {
// Locate the listview in listview_main.xml
listview = (ListView) findViewById(R.id.beg_layoutListView);
// Pass the results into ListViewAdapter.java
adapter = new FinalAdapter(MainActivity.this,
codelist);
// Binds the Adapter to the ListView
listview.setAdapter(adapter);
// Close the progressdialog
mProgressDialog.dismiss();
}
}
}
codelist.java
public class CodeList
{
private String alphabetimg;
private String listHeading;
private String levelImg;
private String singleItemHeading;
private String description;
private String apiImg;
private String apiText;
private String previewImgOne;
private String previewImgTwo;
private String finalCodeText;
public void setAlphabetimg(String alphabetimg)
{
this.alphabetimg = alphabetimg;
}
public String getAlphabetimg()
{
return alphabetimg;
}
public void setListHeading(String listHeading)
{
this.listHeading = listHeading;
}
public String getListHeading()
{
return listHeading;
}
public void setLevelImg(String levelImg)
{
this.levelImg = levelImg;
}
public String getLevelImg()
{
return levelImg;
}
public void setSingleItemHeading(String singleItemHeading)
{
this.singleItemHeading = singleItemHeading;
}
public String getSingleItemHeading()
{
return singleItemHeading;
}
public void setDescription(String description)
{
this.description = description;
}
public String getDescription()
{
return description;
}
public void setApiImg(String apiImg)
{
this.apiImg = apiImg;
}
public String getApiImg()
{
return apiImg;
}
public void setApiText(String apiText)
{
this.apiText = apiText;
}
public String getApiText()
{
return apiText;
}
public void setPreviewImgOne(String previewImgOne)
{
this.previewImgOne = previewImgOne;
}
public String getPreviewImgOne()
{
return previewImgOne;
}
public void setPreviewImgTwo(String previewImgTwo)
{
this.previewImgTwo = previewImgTwo;
}
public String getPreviewImgTwo()
{
return previewImgTwo;
}
public void setFinalCodeText(String finalCodeText)
{
this.finalCodeText = finalCodeText;
}
public String getFinalCodeText()
{
return finalCodeText;
}
}
parse application.java
public class ParseApplication extends Application {
#Override
public void onCreate() {
super.onCreate();
// Add your initialization code here
Parse.initialize(this, "4rOrqK23m0nVq187Of3rhDe0TK1R7FObdBWhfX10", "afKA4B9ohvk3M9pZNv9qK2ypbrdOpXi0FPnrXOu6");
ParseUser.enableAutomaticUser();
ParseACL defaultACL = new ParseACL();
// If you would like all objects to be private by default, remove this line.
defaultACL.setPublicReadAccess(true);
ParseACL.setDefaultACL(defaultACL, true);
}
}
final adapter.java
public class FinalAdapter extends BaseAdapter
{
Context context;
LayoutInflater inflater;
ImageLoader imageLoader;
private List<CodeList> codeList = null;
private ArrayList<CodeList> arraylist;
public FinalAdapter(Context context,
List<CodeList> codeList) {
this.context = context;
this.codeList = codeList;
inflater = LayoutInflater.from(context);
this.arraylist = new ArrayList<CodeList>();
this.arraylist.addAll(codeList);
imageLoader = new ImageLoader(context);
}
public class ViewHolder{
TextView listHeading;
ImageView alphabetList;
}
#Override
public int getCount()
{
return codeList.size();
}
#Override
public Object getItem(int position)
{
return codeList.get(position);
}
#Override
public long getItemId(int position)
{
return position;
}
#Override
public View getView(final int position, View view, ViewGroup parent)
{
final ViewHolder holder;
if(view == null){
holder = new ViewHolder();
view = inflater.inflate(R.layout.beg_list_item,null);
holder.listHeading = (TextView) view.findViewById(R.id.beg_list_itemTextView);
holder.alphabetList = (ImageView) view.findViewById(R.id.beg_list_itemImageView);
view.setTag(holder);
}else{
holder = (ViewHolder) view.getTag();
}
holder.listHeading.setText(codeList.get(position).getListHeading());
imageLoader.DisplayImage(codeList.get(position).getAlphabetimg(),
holder.alphabetList);
view.setOnClickListener(new OnClickListener(){
#Override
public void onClick(View arg0){
Intent intent = new Intent(context, SingleItemView.class);
intent.putExtra("listheading",
(codeList.get(position).getListHeading()));
intent.putExtra("alphabetimg",
(codeList.get(position).getAlphabetimg()));
// Start SingleItemView Class
context.startActivity(intent);
}
});
return view;
}
}
singleitemview.java
public class SingleItemView extends Activity.
{
String heading;
String subHeading;
String levelImg;
String apiImg;
String apiText;
String descImgOne;
String descImgTwo;
String codeText;
ImageLoader imgloader = new ImageLoader(this);
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.singleitemview);
Intent i = getIntent();
heading= i.getStringExtra("heading");
subHeading = i.getStringExtra("subheading");
levelImg = i.getStringExtra("levelimg");
apiImg = i.getStringExtra("apiimg");
apiText = i.getStringExtra("apitext");
descImgOne = i.getStringExtra("descimgone");
descImgTwo = i.getStringExtra("descimgtwo");
codeText = i.getStringExtra("codetext");
TextView headingtxt = (TextView)findViewById(R.id.singleitemheading);
TextView subheadingtxt = (TextView)findViewById(R.id.singleitemsubheading);
TextView apitxt = (TextView)findViewById(R.id.singleitemviewapitext);
TextView codetxt = (TextView) findViewById(R.id.singleitemviewcodetext);
ImageView level =(ImageView) findViewById(R.id.levelimg);
ImageView api =(ImageView) findViewById(R.id.singleitemviewapiimg);
ImageView descone =(ImageView) findViewById(R.id.descriptionimgone);
ImageView desctwo =(ImageView) findViewById(R.id.descriptionimgtwo);
headingtxt.setText(heading);
subheadingtxt.setText(subHeading);
apitxt.setText(apiText);
codetxt.setText(codeText);
imgloader.DisplayImage(levelImg, level);
imgloader.DisplayImage(apiImg, api);
imgloader.DisplayImage(descImgOne, descone);
imgloader.DisplayImage(descImgTwo, desctwo);
}
}
image loaded.java
public class ImageLoader {
MemoryCache memoryCache = new MemoryCache();
FileCache fileCache;
private Map<ImageView, String> imageViews = Collections
.synchronizedMap(new WeakHashMap<ImageView, String>());
ExecutorService executorService;
// Handler to display images in UI thread
Handler handler = new Handler();
public ImageLoader(Context context) {
fileCache = new FileCache(context);
executorService = Executors.newFixedThreadPool(5);
}
final int stub_id = R.drawable.temp_img;
public void DisplayImage(String url, ImageView imageView) {
imageViews.put(imageView, url);
Bitmap bitmap = memoryCache.get(url);
if (bitmap != null)
imageView.setImageBitmap(bitmap);
else {
queuePhoto(url, imageView);
imageView.setImageResource(stub_id);
}
}
private void queuePhoto(String url, ImageView imageView) {
PhotoToLoad p = new PhotoToLoad(url, imageView);
executorService.submit(new PhotosLoader(p));
}
private Bitmap getBitmap(String url) {
File f = fileCache.getFile(url);
Bitmap b = decodeFile(f);
if (b != null)
return b;
// Download Images from the Internet
try {
Bitmap bitmap = null;
URL imageUrl = new URL(url);
HttpURLConnection conn = (HttpURLConnection) imageUrl
.openConnection();
conn.setConnectTimeout(30000);
conn.setReadTimeout(30000);
conn.setInstanceFollowRedirects(true);
InputStream is = conn.getInputStream();
OutputStream os = new FileOutputStream(f);
Utils.CopyStream(is, os);
os.close();
conn.disconnect();
bitmap = decodeFile(f);
return bitmap;
} catch (Throwable ex) {
ex.printStackTrace();
if (ex instanceof OutOfMemoryError)
memoryCache.clear();
return null;
}
}
// Decodes image and scales it to reduce memory consumption
private Bitmap decodeFile(File f) {
try {
// Decode image size
BitmapFactory.Options o = new BitmapFactory.Options();
o.inJustDecodeBounds = true;
FileInputStream stream1 = new FileInputStream(f);
BitmapFactory.decodeStream(stream1, null, o);
stream1.close();
// Find the correct scale value. It should be the power of 2.
final int REQUIRED_SIZE = 70;
int width_tmp = o.outWidth, height_tmp = o.outHeight;
int scale = 1;
while (true) {
if (width_tmp / 2 < REQUIRED_SIZE
|| height_tmp / 2 < REQUIRED_SIZE)
break;
width_tmp /= 2;
height_tmp /= 2;
scale *= 2;
}
// Decode with inSampleSize
BitmapFactory.Options o2 = new BitmapFactory.Options();
o2.inSampleSize = scale;
FileInputStream stream2 = new FileInputStream(f);
Bitmap bitmap = BitmapFactory.decodeStream(stream2, null, o2);
stream2.close();
return bitmap;
} catch (FileNotFoundException e) {
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
// Task for the queue
private class PhotoToLoad {
public String url;
public ImageView imageView;
public PhotoToLoad(String u, ImageView i) {
url = u;
imageView = i;
}
}
class PhotosLoader implements Runnable {
PhotoToLoad photoToLoad;
PhotosLoader(PhotoToLoad photoToLoad) {
this.photoToLoad = photoToLoad;
}
#Override
public void run() {
try {
if (imageViewReused(photoToLoad))
return;
Bitmap bmp = getBitmap(photoToLoad.url);
memoryCache.put(photoToLoad.url, bmp);
if (imageViewReused(photoToLoad))
return;
BitmapDisplayer bd = new BitmapDisplayer(bmp, photoToLoad);
handler.post(bd);
} catch (Throwable th) {
th.printStackTrace();
}
}
}
boolean imageViewReused(PhotoToLoad photoToLoad) {
String tag = imageViews.get(photoToLoad.imageView);
if (tag == null || !tag.equals(photoToLoad.url))
return true;
return false;
}
// Used to display bitmap in the UI thread
class BitmapDisplayer implements Runnable {
Bitmap bitmap;
PhotoToLoad photoToLoad;
public BitmapDisplayer(Bitmap b, PhotoToLoad p) {
bitmap = b;
photoToLoad = p;
}
public void run() {
if (imageViewReused(photoToLoad))
return;
if (bitmap != null)
photoToLoad.imageView.setImageBitmap(bitmap);
else
photoToLoad.imageView.setImageResource(stub_id);
}
}
public void clearCache() {
memoryCache.clear();
fileCache.clear();
}
}
filecache.java
public class FileCache {
private File cacheDir;
public FileCache(Context context) {
// Find the dir to save cached images
if (android.os.Environment.getExternalStorageState().equals(
android.os.Environment.MEDIA_MOUNTED))
cacheDir = new File(
android.os.Environment.getExternalStorageDirectory(),
"ImgTxt");
else
cacheDir = context.getCacheDir();
if (!cacheDir.exists())
cacheDir.mkdirs();
}
public File getFile(String url) {
String filename = String.valueOf(url.hashCode());
// String filename = URLEncoder.encode(url);
File f = new File(cacheDir, filename);
return f;
}
public void clear() {
File[] files = cacheDir.listFiles();
if (files == null)
return;
for (File f : files)
f.delete();
}
}
memorycache.java
public class MemoryCache {
private static final String TAG = "MemoryCache";
// Last argument true for LRU ordering
private Map<String, Bitmap> cache = Collections
.synchronizedMap(new LinkedHashMap<String, Bitmap>(10, 1.5f, true));
// Current allocated size
private long size = 0;
// Max memory in bytes
private long limit = 1000000;
public MemoryCache() {
// Use 25% of available heap size
setLimit(Runtime.getRuntime().maxMemory() / 4);
}
public void setLimit(long new_limit) {
limit = new_limit;
Log.i(TAG, "MemoryCache will use up to " + limit / 1024. / 1024. + "MB");
}
public Bitmap get(String id) {
try {
if (!cache.containsKey(id))
return null;
return cache.get(id);
} catch (NullPointerException ex) {
ex.printStackTrace();
return null;
}
}
public void put(String id, Bitmap bitmap) {
try {
if (cache.containsKey(id))
size -= getSizeInBytes(cache.get(id));
cache.put(id, bitmap);
size += getSizeInBytes(bitmap);
checkSize();
} catch (Throwable th) {
th.printStackTrace();
}
}
private void checkSize() {
Log.i(TAG, "cache size=" + size + " length=" + cache.size());
if (size > limit) {
// Least recently accessed item will be the first one iterated
Iterator<Entry<String, Bitmap>> iter = cache.entrySet().iterator();
while (iter.hasNext()) {
Entry<String, Bitmap> entry = iter.next();
size -= getSizeInBytes(entry.getValue());
iter.remove();
if (size <= limit)
break;
}
Log.i(TAG, "Clean cache. New size " + cache.size());
}
}
public void clear() {
try {
cache.clear();
size = 0;
} catch (NullPointerException ex) {
ex.printStackTrace();
}
}
long getSizeInBytes(Bitmap bitmap) {
if (bitmap == null)
return 0;
return bitmap.getRowBytes() * bitmap.getHeight();
}
}
android manifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.mycompany.myapp" >
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<application
android:name="ParseApplication"
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name=".MainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".SingleItemView">
</activity>
</application>
</manifest>

In the onclicklistener() add this code
intent.putExtra("levelimg",
(codeList.get(position).getLevelImg()));
intent.putExtra("heading",
(codeList.get(position).getSingleItemHeading()));
intent.putExtra("subheading",
(codeList.get(position).getDescription()));
intent.putExtra("apitext",
(codeList.get(position).getApiText()));
intent.putExtra("apiimg",
(codeList.get(position).getApiImg()));
intent.putExtra("descimgone",
(codeList.get(position).getPreviewImgOne()));
intent.putExtra("descimgtwo",
(codeList.get(position).getPreviewImgTwo()));
intent.putExtra("codetext",
(codeList.get(position).getFinalCodeText()));

Retrieves nothing from parse.com into singleitemview

My app retrieves information from parse and display it into a list view ,but when the app is run and the list view item is clicked it opens a new activity and display some images and text from parse.com but it shows nothing like the image below
Here is my code
MainActivity
public class MainActivity extends Activity
{
ListView listview;
List<ParseObject> ob;
ProgressDialog mProgressDialog;
FinalAdapter adapter;
private List<CodeList> codelist = null;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.beg_layout);
new RemoteDataTask().execute();
}
private class RemoteDataTask extends AsyncTask<Void, Void, Void>
{
#Override
protected void onPreExecute() {
super.onPreExecute();
// Create a progressdialog
mProgressDialog = new ProgressDialog(MainActivity.this);
// Set progressdialog title
mProgressDialog.setTitle("Testing");
// Set progressdialog message
mProgressDialog.setMessage("Loading. Please wait this may take few moments ....");
mProgressDialog.setIndeterminate(true);
// Show progressdialog
mProgressDialog.show();
}
#Override
protected Void doInBackground(Void... params)
{
codelist = new ArrayList<CodeList>();
try{
ParseQuery<ParseObject> query = new ParseQuery<ParseObject>(
"BeginnerActivity");
query.orderByAscending("_created_at");
ob = query.find();
for(ParseObject begactivity : ob){
ParseFile listimg = (ParseFile) begactivity.get("alphabetimg");
ParseFile levelimg = (ParseFile) begactivity.get("levelimg");
ParseFile apiimg = (ParseFile) begactivity.get("apiimg");
ParseFile descimgone = (ParseFile) begactivity.get("descimgone");
ParseFile descimgtwo = (ParseFile) begactivity.get("descimgtwo");
CodeList map = new CodeList();
map.setListHeading((String) begactivity.get("listheading"));
map.setSingleItemHeading((String) begactivity.get("heading"));
map.setDescription((String) begactivity.get("subheading"));
map.setApiText((String) begactivity.get("apitext"));
map.setFinalCodeText((String) begactivity.get("codetext"));
map.setAlphabetimg(listimg.getUrl());
map.setLevelImg(levelimg.getUrl());
map.setApiImg(apiimg.getUrl());
map.setPreviewImgOne(descimgone.getUrl());
map.setPreviewImgTwo(descimgtwo.getUrl());
codelist.add(map);
}
}catch(ParseException e){
Log.e("Error", e.getMessage());
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(Void result) {
// Locate the listview in listview_main.xml
listview = (ListView) findViewById(R.id.beg_layoutListView);
// Pass the results into ListViewAdapter.java
adapter = new FinalAdapter(MainActivity.this,
codelist);
// Binds the Adapter to the ListView
listview.setAdapter(adapter);
// Close the progressdialog
mProgressDialog.dismiss();
}
}
}
CodeList
public class CodeList
{
private String alphabetimg;
private String listHeading;
private String levelImg;
private String singleItemHeading;
private String description;
private String apiImg;
private String apiText;
private String previewImgOne;
private String previewImgTwo;
private String finalCodeText;
public void setAlphabetimg(String alphabetimg)
{
this.alphabetimg = alphabetimg;
}
public String getAlphabetimg()
{
return alphabetimg;
}
public void setListHeading(String listHeading)
{
this.listHeading = listHeading;
}
public String getListHeading()
{
return listHeading;
}
public void setLevelImg(String levelImg)
{
this.levelImg = levelImg;
}
public String getLevelImg()
{
return levelImg;
}
public void setSingleItemHeading(String singleItemHeading)
{
this.singleItemHeading = singleItemHeading;
}
public String getSingleItemHeading()
{
return singleItemHeading;
}
public void setDescription(String description)
{
this.description = description;
}
public String getDescription()
{
return description;
}
public void setApiImg(String apiImg)
{
this.apiImg = apiImg;
}
public String getApiImg()
{
return apiImg;
}
public void setApiText(String apiText)
{
this.apiText = apiText;
}
public String getApiText()
{
return apiText;
}
public void setPreviewImgOne(String previewImgOne)
{
this.previewImgOne = previewImgOne;
}
public String getPreviewImgOne()
{
return previewImgOne;
}
public void setPreviewImgTwo(String previewImgTwo)
{
this.previewImgTwo = previewImgTwo;
}
public String getPreviewImgTwo()
{
return previewImgTwo;
}
public void setFinalCodeText(String finalCodeText)
{
this.finalCodeText = finalCodeText;
}
public String getFinalCodeText()
{
return finalCodeText;
}
}
ParseApplication
public class ParseApplication extends Application {
#Override
public void onCreate() {
super.onCreate();
// Add your initialization code here
Parse.initialize(this, "4rOrqK23m0nVq187Of3rhDe0TK1R7FObdBWhfX10", "afKA4B9ohvk3M9pZNv9qK2ypbrdOpXi0FPnrXOu6");
ParseUser.enableAutomaticUser();
ParseACL defaultACL = new ParseACL();
// If you would like all objects to be private by default, remove this line.
defaultACL.setPublicReadAccess(true);
ParseACL.setDefaultACL(defaultACL, true);
}
}
FinalAdapter
public class FinalAdapter extends BaseAdapter
{
Context context;
LayoutInflater inflater;
ImageLoader imageLoader;
private List<CodeList> codeList = null;
private ArrayList<CodeList> arraylist;
public FinalAdapter(Context context,
List<CodeList> codeList) {
this.context = context;
this.codeList = codeList;
inflater = LayoutInflater.from(context);
this.arraylist = new ArrayList<CodeList>();
this.arraylist.addAll(codeList);
imageLoader = new ImageLoader(context);
}
public class ViewHolder{
TextView listHeading;
ImageView alphabetList;
}
#Override
public int getCount()
{
return codeList.size();
}
#Override
public Object getItem(int position)
{
return codeList.get(position);
}
#Override
public long getItemId(int position)
{
return position;
}
#Override
public View getView(final int position, View view, ViewGroup parent)
{
final ViewHolder holder;
if(view == null){
holder = new ViewHolder();
view = inflater.inflate(R.layout.beg_list_item,null);
holder.listHeading = (TextView) view.findViewById(R.id.beg_list_itemTextView);
holder.alphabetList = (ImageView) view.findViewById(R.id.beg_list_itemImageView);
view.setTag(holder);
}else{
holder = (ViewHolder) view.getTag();
}
holder.listHeading.setText(codeList.get(position).getListHeading());
imageLoader.DisplayImage(codeList.get(position).getAlphabetimg(),
holder.alphabetList);
view.setOnClickListener(new OnClickListener(){
#Override
public void onClick(View arg0){
Intent intent = new Intent(context, SingleItemView.class);
intent.putExtra("listheading",
(codeList.get(position).getListHeading()));
intent.putExtra("alphabetimg",
(codeList.get(position).getAlphabetimg()));
// Start SingleItemView Class
context.startActivity(intent);
}
});
return view;
}
}
SingleItemView
public class SingleItemView extends Activity.
{
String heading;
String subHeading;
String levelImg;
String apiImg;
String apiText;
String descImgOne;
String descImgTwo;
String codeText;
ImageLoader imgloader = new ImageLoader(this);
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.singleitemview);
Intent i = getIntent();
heading= i.getStringExtra("heading");
subHeading = i.getStringExtra("subheading");
levelImg = i.getStringExtra("levelimg");
apiImg = i.getStringExtra("apiimg");
apiText = i.getStringExtra("apitext");
descImgOne = i.getStringExtra("descimgone");
descImgTwo = i.getStringExtra("descimgtwo");
codeText = i.getStringExtra("codetext");
TextView headingtxt = (TextView)findViewById(R.id.singleitemheading);
TextView subheadingtxt = (TextView)findViewById(R.id.singleitemsubheading);
TextView apitxt = (TextView)findViewById(R.id.singleitemviewapitext);
TextView codetxt = (TextView) findViewById(R.id.singleitemviewcodetext);
ImageView level =(ImageView) findViewById(R.id.levelimg);
ImageView api =(ImageView) findViewById(R.id.singleitemviewapiimg);
ImageView descone =(ImageView) findViewById(R.id.descriptionimgone);
ImageView desctwo =(ImageView) findViewById(R.id.descriptionimgtwo);
headingtxt.setText(heading);
subheadingtxt.setText(subHeading);
apitxt.setText(apiText);
codetxt.setText(codeText);
imgloader.DisplayImage(levelImg, level);
imgloader.DisplayImage(apiImg, api);
imgloader.DisplayImage(descImgOne, descone);
imgloader.DisplayImage(descImgTwo, desctwo);
}
}
ImageLoader
public class ImageLoader {
MemoryCache memoryCache = new MemoryCache();
FileCache fileCache;
private Map<ImageView, String> imageViews = Collections
.synchronizedMap(new WeakHashMap<ImageView, String>());
ExecutorService executorService;
// Handler to display images in UI thread
Handler handler = new Handler();
public ImageLoader(Context context) {
fileCache = new FileCache(context);
executorService = Executors.newFixedThreadPool(5);
}
final int stub_id = R.drawable.temp_img;
public void DisplayImage(String url, ImageView imageView) {
imageViews.put(imageView, url);
Bitmap bitmap = memoryCache.get(url);
if (bitmap != null)
imageView.setImageBitmap(bitmap);
else {
queuePhoto(url, imageView);
imageView.setImageResource(stub_id);
}
}
private void queuePhoto(String url, ImageView imageView) {
PhotoToLoad p = new PhotoToLoad(url, imageView);
executorService.submit(new PhotosLoader(p));
}
private Bitmap getBitmap(String url) {
File f = fileCache.getFile(url);
Bitmap b = decodeFile(f);
if (b != null)
return b;
// Download Images from the Internet
try {
Bitmap bitmap = null;
URL imageUrl = new URL(url);
HttpURLConnection conn = (HttpURLConnection) imageUrl
.openConnection();
conn.setConnectTimeout(30000);
conn.setReadTimeout(30000);
conn.setInstanceFollowRedirects(true);
InputStream is = conn.getInputStream();
OutputStream os = new FileOutputStream(f);
Utils.CopyStream(is, os);
os.close();
conn.disconnect();
bitmap = decodeFile(f);
return bitmap;
} catch (Throwable ex) {
ex.printStackTrace();
if (ex instanceof OutOfMemoryError)
memoryCache.clear();
return null;
}
}
// Decodes image and scales it to reduce memory consumption
private Bitmap decodeFile(File f) {
try {
// Decode image size
BitmapFactory.Options o = new BitmapFactory.Options();
o.inJustDecodeBounds = true;
FileInputStream stream1 = new FileInputStream(f);
BitmapFactory.decodeStream(stream1, null, o);
stream1.close();
// Find the correct scale value. It should be the power of 2.
final int REQUIRED_SIZE = 70;
int width_tmp = o.outWidth, height_tmp = o.outHeight;
int scale = 1;
while (true) {
if (width_tmp / 2 < REQUIRED_SIZE
|| height_tmp / 2 < REQUIRED_SIZE)
break;
width_tmp /= 2;
height_tmp /= 2;
scale *= 2;
}
// Decode with inSampleSize
BitmapFactory.Options o2 = new BitmapFactory.Options();
o2.inSampleSize = scale;
FileInputStream stream2 = new FileInputStream(f);
Bitmap bitmap = BitmapFactory.decodeStream(stream2, null, o2);
stream2.close();
return bitmap;
} catch (FileNotFoundException e) {
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
// Task for the queue
private class PhotoToLoad {
public String url;
public ImageView imageView;
public PhotoToLoad(String u, ImageView i) {
url = u;
imageView = i;
}
}
class PhotosLoader implements Runnable {
PhotoToLoad photoToLoad;
PhotosLoader(PhotoToLoad photoToLoad) {
this.photoToLoad = photoToLoad;
}
#Override
public void run() {
try {
if (imageViewReused(photoToLoad))
return;
Bitmap bmp = getBitmap(photoToLoad.url);
memoryCache.put(photoToLoad.url, bmp);
if (imageViewReused(photoToLoad))
return;
BitmapDisplayer bd = new BitmapDisplayer(bmp, photoToLoad);
handler.post(bd);
} catch (Throwable th) {
th.printStackTrace();
}
}
}
boolean imageViewReused(PhotoToLoad photoToLoad) {
String tag = imageViews.get(photoToLoad.imageView);
if (tag == null || !tag.equals(photoToLoad.url))
return true;
return false;
}
// Used to display bitmap in the UI thread
class BitmapDisplayer implements Runnable {
Bitmap bitmap;
PhotoToLoad photoToLoad;
public BitmapDisplayer(Bitmap b, PhotoToLoad p) {
bitmap = b;
photoToLoad = p;
}
public void run() {
if (imageViewReused(photoToLoad))
return;
if (bitmap != null)
photoToLoad.imageView.setImageBitmap(bitmap);
else
photoToLoad.imageView.setImageResource(stub_id);
}
}
public void clearCache() {
memoryCache.clear();
fileCache.clear();
}
}
MemoryCache
public class MemoryCache {
private static final String TAG = "MemoryCache";
// Last argument true for LRU ordering
private Map<String, Bitmap> cache = Collections
.synchronizedMap(new LinkedHashMap<String, Bitmap>(10, 1.5f, true));
// Current allocated size
private long size = 0;
// Max memory in bytes
private long limit = 1000000;
public MemoryCache() {
// Use 25% of available heap size
setLimit(Runtime.getRuntime().maxMemory() / 4);
}
public void setLimit(long new_limit) {
limit = new_limit;
Log.i(TAG, "MemoryCache will use up to " + limit / 1024. / 1024. + "MB");
}
public Bitmap get(String id) {
try {
if (!cache.containsKey(id))
return null;
return cache.get(id);
} catch (NullPointerException ex) {
ex.printStackTrace();
return null;
}
}
public void put(String id, Bitmap bitmap) {
try {
if (cache.containsKey(id))
size -= getSizeInBytes(cache.get(id));
cache.put(id, bitmap);
size += getSizeInBytes(bitmap);
checkSize();
} catch (Throwable th) {
th.printStackTrace();
}
}
private void checkSize() {
Log.i(TAG, "cache size=" + size + " length=" + cache.size());
if (size > limit) {
// Least recently accessed item will be the first one iterated
Iterator<Entry<String, Bitmap>> iter = cache.entrySet().iterator();
while (iter.hasNext()) {
Entry<String, Bitmap> entry = iter.next();
size -= getSizeInBytes(entry.getValue());
iter.remove();
if (size <= limit)
break;
}
Log.i(TAG, "Clean cache. New size " + cache.size());
}
}
public void clear() {
try {
cache.clear();
size = 0;
} catch (NullPointerException ex) {
ex.printStackTrace();
}
}
long getSizeInBytes(Bitmap bitmap) {
if (bitmap == null)
return 0;
return bitmap.getRowBytes() * bitmap.getHeight();
}
}
FileCache
public class FileCache {
private File cacheDir;
public FileCache(Context context) {
// Find the dir to save cached images
if (android.os.Environment.getExternalStorageState().equals(
android.os.Environment.MEDIA_MOUNTED))
cacheDir = new File(
android.os.Environment.getExternalStorageDirectory(),
"ImgTxt");
else
cacheDir = context.getCacheDir();
if (!cacheDir.exists())
cacheDir.mkdirs();
}
public File getFile(String url) {
String filename = String.valueOf(url.hashCode());
// String filename = URLEncoder.encode(url);
File f = new File(cacheDir, filename);
return f;
}
public void clear() {
File[] files = cacheDir.listFiles();
if (files == null)
return;
for (File f : files)
f.delete();
}
}
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.mycompany.myapp" >
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<application
android:name="ParseApplication"
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name=".MainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".SingleItemView">
</activity>
</application>
</manifest>

Android ListView wrong images

I'm developing an Android app but I'm a newbie and I got stuck...
My ListView single element has an ImageView and some TextViews, but sometimes (when I scroll the page and there are more than 7-8 elements) it doesn't display the right image in the right row.
I'm using a custom Image Loader to manage the downloaded images.
Here's my Adapter:
public class AddVideogameActivityAdapter extends BaseAdapter {
private ArrayList<Videogame> videogames;
private Typeface typefaceMedium;
private Typeface typefaceLight;
private ImageLoader loader;
private LayoutInflater mInflater;
public AddVideogameActivityAdapter(Context context, ArrayList<Videogame> results) {
videogames = results;
mInflater = LayoutInflater.from(context);
typefaceMedium = Typeface.createFromAsset(context.getAssets(), "Roboto-Medium.ttf");
typefaceLight = Typeface.createFromAsset(context.getAssets(), "Roboto-Light.ttf");
loader = new ImageLoader(context);
}
public int getCount() {
return videogames.size();
}
public Object getItem(int position) {
return videogames.get(position);
}
public long getItemId(int position) {
return position;
}
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder;
if (convertView == null) {
convertView = mInflater.inflate(R.layout.list_element,null);
holder = new ViewHolder();
holder.imgView = (ImageView) convertView.findViewById(R.id.thumbView);
holder.txtName = (TextView) convertView.findViewById(R.id.elementView);
holder.txtPlatform = (TextView) convertView.findViewById(R.id.elementView2);
convertView.setTag(holder);
}
else {
holder = (ViewHolder) convertView.getTag();
}
try {
Videogame vgame = (Videogame) videogames.get(position);
holder.txtName.setText(vgame.getTitle());
holder.txtName.setTypeface(typefaceMedium);
holder.txtPlatform.setText(videogames.get(position).getPlatform());
holder.txtPlatform.setTypeface(typefaceLight);
holder.imgUrl = videogames.get(position).getImage();
loader.display(holder.imgUrl, holder.imgView, R.drawable.youtube_icon);
}
catch (Exception e) {
e.printStackTrace();
Log.e(com.example.ludos2_0.MainActivity.TAG,
"Exception: " + e.getLocalizedMessage());
}
return convertView;
}
static class ViewHolder {
TextView txtName;
TextView txtPlatform;
public String imgUrl;
ImageView imgView;
}
}
Sorry for my english and thank you for your help!
EDIT:
Here's also the Loader:
public class ImageLoader implements ComponentCallbacks2 {
private TCLruCache cache;
public ImageLoader(Context context) {
ActivityManager am = (ActivityManager) context.getSystemService(
Context.ACTIVITY_SERVICE);
int memoryClass = am.getMemoryClass() * 1024 * 1024;
cache = new TCLruCache(memoryClass);
}
public void display(String url, ImageView imageview, int defaultresource) {
imageview.setImageResource(defaultresource);
Bitmap image = cache.get(url);
if (image != null) {
imageview.setImageBitmap(image);
}
else {
new SetImageTask(imageview).execute(url);
}
}
private class TCLruCache extends LruCache<String, Bitmap> {
public TCLruCache(int maxSize) {
super(maxSize);
}
}
private class SetImageTask extends AsyncTask<String, Void, Integer> {
private ImageView imageview;
private Bitmap bmp;
public SetImageTask(ImageView imageview) {
this.imageview = imageview;
}
#Override
protected Integer doInBackground(String... params) {
String url = params[0];
try {
bmp = getBitmapFromURL(url);
if (bmp != null) {
cache.put(url, bmp);
}
else {
return 0;
}
} catch (Exception e) {
e.printStackTrace();
return 0;
}
return 1;
}
#Override
protected void onPostExecute(Integer result) {
if (result == 1) {
imageview.setImageBitmap(bmp);
}
super.onPostExecute(result);
}
private Bitmap getBitmapFromURL(String src) {
try {
URL url = new URL(src);
HttpURLConnection connection
= (HttpURLConnection) url.openConnection();
connection.setDoInput(true);
connection.connect();
InputStream input = connection.getInputStream();
Bitmap myBitmap = BitmapFactory.decodeStream(input);
return myBitmap;
} catch (IOException e) {
e.printStackTrace();
return null;
}
}
}
}
RE-EDIT
Activity code:
public class AddVideogameActivity extends ListActivity {
private TextView searchField = null;
private final Handler handler = new Handler();
private ArrayList<Videogame> videogamesList = null;
private static AddVideogameActivity mContext = null;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_add_book);
mContext = this;
searchField = (TextView) findViewById(R.id.searchField);
searchField.setMaxLines(1);
searchField.setOnFocusChangeListener(new OnFocusChangeListener() {
#Override
public void onFocusChange(View v, boolean hasFocus) {
searchField.setHint("");
}
});
// Setup the list view and its listener
getListView().setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
Log.d(MainActivity.TAG,
"AddBookActivity ---> AddButton:onClick()");
// Sets typefaces for TextView
String videogameId = videogamesList.get(position).getId();
String videogameName = videogamesList.get(position).getTitle();
String thumbnail = videogamesList.get(position).getThumbnail();
String description = videogamesList.get(position)
.getDescription();
String image = videogamesList.get(position).getImage();
String platform = videogamesList.get(position).getPlatform();
if (videogameName != null && videogameName.length() > 0
&& thumbnail != null && thumbnail.length() > 0
&& description != null && description.length() > 0
&& image != null && image.length() > 0
&& platform != null && platform.length() > 0) {
if (ListsManager.getInstance().addVideogame(
new Videogame(videogameId, videogameName,
thumbnail, image, description, platform)) == 0) {
Log.d(MainActivity.TAG,
"AddBookActivity --> Videogame:[" + videogameId
+ "#" + videogameName + "]");
Toast toast = Toast.makeText(mContext, "["
+ videogameName + "] Saved !",
Toast.LENGTH_LONG);
toast.show();
} else {
Log.e(MainActivity.TAG,
"AddBookActivity --> Error ! Videogame already in the list ! ");
Toast toast = Toast.makeText(mContext,
"Error! Videogame already in the list!",
Toast.LENGTH_LONG);
toast.show();
}
} else {
Log.e(MainActivity.TAG,
"AddBookActivity --> Error ! Invalid Videogame Name or Thumbnail or Id or Deck");
Toast toast = Toast
.makeText(
mContext,
"Error ! Invalid Videogame Name or Thumbnail or Id or Deck",
Toast.LENGTH_LONG);
toast.show();
}
Intent newIntent = new Intent(getApplicationContext(),
MainActivity.class);
startActivity(newIntent);
}
});
// Setup the search button and its listener
Button searchButton = (Button) findViewById(R.id.searchButton);
searchButton.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
Log.d(com.example.ludos2_0.MainActivity.TAG, "Search Game ...");
String searchInputString = searchField.getText().toString();
if (searchInputString != null && searchInputString.length() > 0) {
try {
String requestURL = ("http://www.giantbomb.com/api/search/?api_key=fcf60d6d67b98b0d17b3905d1a90b3fd31ed1e8e&format=json&query="
+ Uri.encode(searchInputString) + "&resources=game");
// String requestURL =
// String.format("https://gdata.youtube.com/feeds/api/videos?v=2&alt=jsonc&category=Music&orderby=relevance&q=%s",Uri.encode(searchInputString));
Log.d(com.example.ludos2_0.MainActivity.TAG, requestURL);
DownloadGiantBombJSONData giantbombAsyncTask = new DownloadGiantBombJSONData();
giantbombAsyncTask.execute(new String[] { requestURL });
} catch (Exception e) {
e.printStackTrace();
}
}
}
});
if (videogamesList == null)
videogamesList = new ArrayList<Videogame>();
else
updateVideogamesListView(videogamesList);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.add_book, menu);
return true;
}
#Override
protected void onResume() {
super.onResume();
}
#Override
protected void onPause() {
super.onPause();
}
public void updateVideogamesListView(ArrayList<Videogame> values) {
AddVideogameActivityAdapter adapter = new AddVideogameActivityAdapter(this, values);
setListAdapter(adapter);
}
#Override
protected void onDestroy() {
super.onDestroy();
}
}
The other classes involved in building the ListView are the REST classes and the AsyncTask class that downloads and parses the JSon files.

What does your ListView look like, does it look like this:
<ListView android:id="#id/android:list"
android:layout_weight="1"
android:layout_width="match_parent"
android:layout_height="0dip" ></ListView>
Especially the id of the ListView. Check your layout file, probably the bug exists there.

Drawables won't load using AsyncTask

I have the queryAppIcon() method that queries and stores images in the array appIconDrawable. However, I'm only getting blank where images should pop up. Please let me know if I should post any other relevant code
This is the relevant code inside the ViewActivity:
// global vars
final Drawable[] appIconDrawable = null;
int i;
public Drawable[] queryAppIcon() throws ParseException, IOException {
ParseQuery<ParseObject> query = ParseQuery.getQuery("AndroidStoreContent");
query.whereExists("appIcon");
List<ParseObject> ParseResult = query.find();
// Drawable array
appIconDrawable = new Drawable[ParseResult.size()];
for (i = 0; i < ParseResult.size(); i++) {
ParseFile pf = (ParseFile) ParseResult.get(i).get("appIcon");
startDownload(pf);
}
return appIconDrawable;
}
public void startDownload(ParseFile pf) {
new DownloadImageTask(this).execute(pf);
}
public class DownloadImageTask extends AsyncTask<ParseFile, Void, Drawable> {
private AsyncResponse ar;
DownloadImageTask(AsyncResponse ar) {
this.ar = ar;
}
#Override
protected Drawable doInBackground(ParseFile... pf) {
return fetchDrawable(pf[0]);
}
protected void onPostExecute(Drawable result) {
ar.processFinish(result);
}
public Drawable fetchDrawable(ParseFile pf) {
InputStream is;
try {
is = (InputStream) new URL(pf.getUrl()).getContent();
return Drawable.createFromStream(is,null);
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
}
#Override
public void processFinish(Drawable d) {
appIconDrawable[i] = d; // i also tried testing appIconDrawable[1] = d and the app loaded with all blank images and then crashes
}
This is the interface, AsyncResponse:
public interface AsyncResponse {
void processFinish(Drawable d);
}

It seems like you need a bit of refactor...
You are expecting Drawable[] from queryAppIcon() but you will always get an empty set because you start the download which takes place in a separate thread to then update the return value.
You should be setting the Drawable to the ImageView from within processFinish.
Signs of things done wrong: Async methods such as downloading images should never have a return value.
UPDATE
Here is a very simple download AsyncTask but there are many checks, optimizations, etc. missing, like CACHE! Also, ImageView inside DownloadImageTask should be held by a WeakReference (Google it) otherwise it WILL leak your activity.
public class DownloadImageTask extends AsyncTask<String, Void, Drawable> {
private static final String TAG = DownloadImageTask.class.getSimpleName();
private ImageView mImageView;
DownloadImageTask(ImageView imageView) {
mImageView = imageView;
}
#Override
protected Drawable doInBackground(String... url) {
return fetchDrawable(url[0]);
}
#Override
protected void onPostExecute(Drawable result) {
if (result != null) {
mImageView.setImageDrawable(result);
} else {
Log.w(TAG, "Could download image!");
}
}
public static Drawable fetchDrawable(String url) {
Log.v(TAG, "Downloading: " + url);
InputStream is;
try {
is = (InputStream) new URL(url).getContent();
return Drawable.createFromStream(is, null);
} catch (MalformedURLException e) {
Log.e(TAG, e.getMessage(), e);
} catch (IOException e) {
Log.e(TAG, e.getMessage(), e);
}
return null;
}
}
Adapter:
public class ImageDownloadAdapter extends ArrayAdapter<String>{
public ImageDownloadAdapter(Context context, String[] objects) {
super(context, R.layout.item_image_download, R.id.txt_url, objects);
}
#SuppressLint("NewApi")
#Override
public View getView(int position, View convertView, ViewGroup parent) {
View view = super.getView(position, convertView, parent);
String url = getItem(position);
ImageView imageView = (ImageView) view.findViewById(R.id.img_download);
DownloadImageTask downloadImageTask = new DownloadImageTask(imageView);
if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
downloadImageTask.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, url);
} else {
downloadImageTask.execute(url);
}
return view;
}
}
Activity:
ListView listView = (ListView) findViewById(android.R.id.list);
listView.setAdapter(new ImageDownloadAdapter(this, new String[]{
"http://www.beautystat.com/site/wp-content/uploads/2011/02/happy-faces-small.jpg",
"http://www.ducthide.com/new_wallet_pics/happy_face.JPG"
}));