Develop Reference

Downloading image and loading it in a imageview in listitem

I'm new to android, I work on an app. I want to download an image and show it in list item. I used many functions for that. My code runs without error but image doesn't display on screen that's part of my code.
public loader(Context context, String[] img) {
super(context, R.layout.item, img);
this.context = context;
this.img = img;
inflater = LayoutInflater.from(context);
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
// ImageView imgshow = (ImageView) findViewById(R.id.image1);
if (null == convertView) {
convertView = inflater.inflate(R.layout.item, parent, false);
}
ImageView imageView = (ImageView) convertView.findViewById(R.id.imageview);
//first method
// Glide.with(context)
// .load(img[position])
//.into(imageView);
//second method
DownloadImageTask download=new DownloadImageTask((ImageView) convertView.findViewById(R.id.imageview));
download.execute("http://previews.123rf.com/images/faysalfarhan/faysalfarhan1402/faysalfarhan140200008/25989999-Back-left-arrow-icon-glossy-purple-button-Stock-Photo.jpg");
//new DownloadImageTask((ImageView) convertView.findViewById(R.id.imageview))
//.execute(img[position]);
//third method
//Picasso.with(context).load(img[position]).into(imageView);
//Log.e("image_url","https://upload.wikimedia.org/wikipedia/commons/thumb/2/27/Square_200x200.svg/1024px-Square_200x200.svg.png");
return convertView;
}
private class DownloadImageTask extends AsyncTask<String, Void, Bitmap> {
ImageView bmImage;
TextView t;
public DownloadImageTask(ImageView bmImage) {
this.bmImage = bmImage;
}
protected Bitmap doInBackground(String... urls) {
String urldisplay = "http://previews.123rf.com/images/faysalfarhan/faysalfarhan1402/faysalfarhan140200008/25989999-Back-left-arrow-icon-glossy-purple-button-Stock-Photo.jpg";
Bitmap mIcon11 = null;
// Toast.makeText(mainpage.this ,urldisplay ,Toast.LENGTH_SHORT).show();
TextView t=(TextView)findViewById(R.id.texttt);
// t.setText(urldisplay);
try {
InputStream in = new java.net.URL(urldisplay).openStream();
mIcon11 = BitmapFactory.decodeStream(in);
} catch (Exception e) {
Log.e("Error", e.getMessage());
e.printStackTrace();
}
return mIcon11;
}
protected void onPostExecute(Bitmap result) {
bmImage.setImageBitmap(result);
}
}
}
I put that in my list using (img is array of strings I save urls in it and display them but for testing I replace it by one image url inside loader class)
String[] img = new String[1000];
loader im=new loader(mainpage.this,img);
lv.setAdapter(im);

you can't set image in ImageView directly. you have to convert that image in Bitmap and then set
public static Bitmap getBitmapFromURL(String src) {
try {
Log.e("src",src);
URL url = new URL(src);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setDoInput(true);
connection.connect();
InputStream input = connection.getInputStream();
Bitmap myBitmap = BitmapFactory.decodeStream(input);
Log.e("Bitmap","returned");
return myBitmap;
} catch (IOException e) {
e.printStackTrace();
Log.e("Exception",e.getMessage());
return null;
}
}
and then set to imageview :
imageView.setImageBitmap(getBitmapFromURL(url));
try this hope it helps you

Picasso.with(context).load("http://i.imgur.com/DvpvklR.png").into(imageView);

Use piccasso.
To use piccasso to add it add
compile 'com.squareup.picasso:picasso:2.5.2'
To your app level gradle. And
use this
Picasso.with(context).load("http://previews.123rf.com/images/faysalfarhan/faysalfarhan1402/faysalfarhan140200008/25989999-Back-left-arrow-icon-glossy-purple-button-Stock-Photo.jpg").into(imageview);
or maybe your getCount() method is returning 0. (or add it) change it to
#Override
public int getCount() {
return img.length;
}

Use Glide
dependency for glide: compile 'com.github.bumptech.glide:glide:3.7.0'
and add the code
ImageView imageView = (ImageView) findViewById(R.id.my_image_view);
Glide.with(this).load("https://s3-us-west-1.amazonaws.com/powr/defaults/image-slider2.jpg").into(imageView);

How to display dynamic ImageView from URL in infoWindow

I'm trying to download an image and show it as an ImageView in my infoWindow , working with InfoWindowsAdapter , i put all the necessary code in the getInfoContents() method, but i can't get the image , in fact i can get it but still can't show it .
As i read in the documentation,i have to recall the treatment to set the downloaded image , i have to use showInfoWindow() method because it's the only way to do it . I tried to use it in getInfoContents() just before the return but , it blocks my app , need help !
This is my getInfoContents() :
public View getInfoContents(Marker marker) {
// set the view
View v = (View) getLayoutInflater().inflate(R.layout.info_window,null);
//assign values to the view field
ImageView imagePlace =(ImageView) v.findViewById(R.id.imageview1);
TextView tvLocality = (TextView) v.findViewById(R.id.tv_place);
//setting values with the parameter
Picasso.with(getApplicationContext()).load(url_image_place).into(imagePlace);
tvLocality.setText(marker.getTitle());
//marker.showInfoWindow();
return v;
}
This my downloadIcon() :
private Bitmap downloadIcon(String iconURL) {
Bitmap bmImg = null;
try {
URL url = new URL(iconURL);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setDoInput(true);
conn.connect();
InputStream is = conn.getInputStream();
bmImg = BitmapFactory.decodeStream(is);
} catch (IOException e) {
e.printStackTrace();
bmImg = null;
}
return bmImg;
}
EDIT :
I used picasso to download my image , but the image is shown only after the second click , and any marker's infowindow that use the same image get the image in the first time , it means that the image have to be downloaded first !! i edited my getInfoContents() and i'm not using downloadIcon() anymore !

Using Picasso, this is extremely easy. Simply write:
String url = ...;//Your url
ImageView imageView; //Your ImageView
Picasso.with(context).load(url).into(imageView);
Or, If you want to do it yourself, you can implement an AsyncTask:
Definition:
private class ImageDownloader extends AsyncTask {
#Override
protected Bitmap doInBackground(String... param) {
return downloadIcon(param[0]);
}
#Override
protected void onPostExecute(Bitmap result) {
//Handle your result, i.e. your bitmap
}
}
Execution:
new ImageDownloader().execute(iconURL);

You should not dowmload image by using main UI thread, so you need another thread to do it, something like:
public void setImage(final ImageView img, final String iconURL)
{
Thread thread = new Thread(new Runnable() {
#Override
public void run()
{
Bitmap bmImg;
try {
URL url = new URL(iconURL);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setDoInput(true);
conn.connect();
InputStream is = conn.getInputStream();
bmImg = BitmapFactory.decodeStream(is);
}
catch (IOException e) {
e.printStackTrace();
bmImg = null;
}
//after downloading, then talk to main ui
runOnUiThread(new Runnable()
{
#Override
public void run()
{
img.setImageBitmap(bmImg);
}
}
}}).start();
}
Hope this help!

android.os.NetworkOnMainThreadException in AsyncTask's doInBackground

Why do I get in an AsyncTask which should a android.os.NetworkOnMainThreadException? I thought that an AsyncTask is the solution to that problem. The exxeption is on line 7.
private class ImageDownloadTask extends AsyncTask<String, Integer, byte[]> {
#Override
protected byte[] doInBackground(String... params) {
try {
URL url = new URL(params[0]);
URLConnection connection = url.openConnection();
InputStream inputStream = connection.getInputStream();
ByteArrayOutputStream byteBuffer = new ByteArrayOutputStream();
int bufferSize = 1024;
byte[] buffer = new byte[bufferSize];
int len;
while ((len = inputStream.read(buffer)) != -1) {
byteBuffer.write(buffer, 0, len);
}
return byteBuffer.toByteArray();
} catch (IOException ex) {
return new byte[0];
}
}
}
I want to use it for downloading a picture.
public byte[] getProfilePicture(Context context, String id) {
String url = context.getString(R.string.facebook_picture_url_large, id);
ImageDownloadTask task = new ImageDownloadTask();
return task.doInBackground(url);
}

By calling doInBackground() directly, you are not actually using the AsyncTask functionality. Instead, you should call execute() and then use the results by overriding the AsyncTask's onPostExecute() method as explained in the Usage section of that same page.

Best way to download an image and attach it to a ImageView is passing the ImageView as the parameter in your async task and set the URL as a tag of the image view then after downloading the task in the OnPostExecute() set the image to the ImageView look at this example :
public class DownloadImagesTask extends AsyncTask<ImageView, Void, Bitmap> {
ImageView imageView = null;
#Override
protected Bitmap doInBackground(ImageView... imageViews) {
this.imageView = imageViews[0];
return download_Image((String)imageView.getTag());
}
#Override
protected void onPostExecute(Bitmap result) {
imageView.setImageBitmap(result);
}
private Bitmap download_Image(String url) {
...
}
And the Usage will be like this
ImageView mChart = (ImageView) findViewById(R.id.imageview);
String URL = "http://www...someImageUrl ...";
mChart.setTag(URL);
new DownloadImageTask.execute(mChart);
The image will be attached automatically when done, for more memory optimization you could use WeakReference.
Good Luck.

Downloading Image using an Async Task and DIsplaying it in Gallery

I have to download some images and display them using Gallery. For the Image adapter I'm using for the gallery I have to start downloading the images in the get view method using an Async task. My problem is that i cant return the downloaded image view to the calling function. I cant download using the main thread due to networkonmainthread exception.
GalleryActivity
public class GalleryActivity extends Activity {
#Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
setContentView(R.layout.gallery);
((Gallery) findViewById(R.id.gallery)).setAdapter(new ImageAdapter(this));
}
Image Adapter
public class ImageAdapter extends BaseAdapter {
public View getView(int position, View convertView, ViewGroup parent) {
new galleryBackground().execute(Integer.toString(position));
ImageView i =null;
return i;
}
}
Gallery
public class galleryBackground extends AsyncTask<String, Integer, String> {
Bitmap bm;
public String[] myRemoteImages = { ....};
ImageView i = new ImageView(GalleryActivity.this);
#Override
protected String doInBackground(String... arg0) {
try {
URL aURL = new URL(myRemoteImages[Integer.parseInt(arg0[0])]);
URLConnection conn = aURL.openConnection();
conn.connect();
InputStream is = conn.getInputStream();
BufferedInputStream bis = new BufferedInputStream(is);
bm = bitmapFactory.decodeStream(bis);
bis.close();
is.close();
}
#Override
protected void onPostExecute(String result) {
i.setImageBitmap(bm);
i.setScaleType(ImageView.ScaleType.FIT_CENTER);
i.setLayoutParams(new Gallery.LayoutParams(150, 150));
// i have to return this Image view to the calling function
super.onPostExecute(result);
}

This library will solve your problem:
https://github.com/xtremelabs/xl-image_utils_lib-android
Pull the JAR from that repo into your project.
Instantiate an ImageLoader in your Activity/Fragment and pass it in to the adapter.
Call imageLoader.loadImage(imageView, url), and everything is done for you by that system.
The wiki can show you how to plug it in.

Change your Asynctask to
AsyncTask<String, Integer, Bitmap>
which will return you Bitmap and onPostExecute use the Bitmap
You are already passing the position so onPostExecute you can
yourlist.getItem(your position) and set the bitmap

Look at: Lazy load of images in ListView
It does not matter how to display data, your adapter will be the same.

you should return bm from doingBackground();
#Override
protected String doInBackground(String... arg0) {
try{
URL aURL = new URL(myRemoteImages[Integer.parseInt(arg0[0])]);
URLConnection conn = aURL.openConnection();
conn.connect();
InputStream is = conn.getInputStream();
BufferedInputStream bis = new BufferedInputStream(is);
bm = bitmapFactory.decodeStream(bis);
bis.close();
is.close();
return bm;
}
}

Android : Loading an image from the Web with Asynctask

How do I replace the following lines of code with an Asynctask ?
How do you "get back" the Bitmap from the Asynctask ? Thank you.
ImageView mChart = (ImageView) findViewById(R.id.Chart);
String URL = "http://www...anything ...";
mChart.setImageBitmap(download_Image(URL));
public static Bitmap download_Image(String url) {
//---------------------------------------------------
Bitmap bm = null;
try {
URL aURL = new URL(url);
URLConnection conn = aURL.openConnection();
conn.connect();
InputStream is = conn.getInputStream();
BufferedInputStream bis = new BufferedInputStream(is);
bm = BitmapFactory.decodeStream(bis);
bis.close();
is.close();
} catch (IOException e) {
Log.e("Hub","Error getting the image from server : " + e.getMessage().toString());
}
return bm;
//---------------------------------------------------
}
I thought about something like this :
replace :
mChart.setImageBitmap(download_Image(graph_URL));
by something like :
mChart.setImageBitmap(new DownloadImagesTask().execute(graph_URL));
and
public class DownloadImagesTask extends AsyncTask<String, Void, Bitmap> {
#Override
protected Bitmap doInBackground(String... urls) {
return download_Image(urls[0]);
}
#Override
protected void onPostExecute(Bitmap result) {
mChart.setImageBitmap(result); // how do I pass a reference to mChart here ?
}
private Bitmap download_Image(String url) {
//---------------------------------------------------
Bitmap bm = null;
try {
URL aURL = new URL(url);
URLConnection conn = aURL.openConnection();
conn.connect();
InputStream is = conn.getInputStream();
BufferedInputStream bis = new BufferedInputStream(is);
bm = BitmapFactory.decodeStream(bis);
bis.close();
is.close();
} catch (IOException e) {
Log.e("Hub","Error getting the image from server : " + e.getMessage().toString());
}
return bm;
//---------------------------------------------------
}
}
but How do I pass a reference to mChart in onPostExecute(Bitmap result) ???
Do I need to pass it with the URL in some way ?
I would like to replace all my lines of code :
mChart1.setImageBitmap(download_Image(URL_1));
mChart2.setImageBitmap(download_Image(URL_2));
with something similar ... but in Asynctask way !
mChart1.setImageBitmap(new DownloadImagesTask().execute(graph_URL_1));
mChart2.setImageBitmap(new DownloadImagesTask().execute(graph_URL_2));
Is there an easy solution for this ?
Do I get something wrong here ?

If there is no good reason to download the image yourself then I would recommend to use Picasso.
Picasso saves you all the problems with downloading, setting and caching images.
The whole code needed for a simple example is:
Picasso.with(context).load(url).into(imageView);
If you really want to do everything yourself use my older answer below.
If the image is not that big you can just use an anonymous class for the async task.
This would like this:
ImageView mChart = (ImageView) findViewById(R.id.imageview);
String URL = "http://www...anything ...";
mChart.setTag(URL);
new DownloadImageTask.execute(mChart);
The Task class:
public class DownloadImagesTask extends AsyncTask<ImageView, Void, Bitmap> {
ImageView imageView = null;
#Override
protected Bitmap doInBackground(ImageView... imageViews) {
this.imageView = imageViews[0];
return download_Image((String)imageView.getTag());
}
#Override
protected void onPostExecute(Bitmap result) {
imageView.setImageBitmap(result);
}
private Bitmap download_Image(String url) {
...
}
Hiding the URL in the tag is a bit tricky but it looks nicer in the calling class if you have a lot of imageviews that you want to fill this way. It also helps if you are using the ImageView inside a ListView and you want to know if the ImageView was recycled during the download of the image.
I wrote if you Image is not that big because this will result in the task having a implicit pointer to the underlying activity causing the garbage collector to hold the whole activity in memory until the task is finished. If the user moves to another screen of your app while the bitmap is downloading the memory can't be freed and it may make your app and the whole system slower.

Try this code:
ImageView myFirstImage = (ImageView) findViewById(R.id.myFirstImage);
ImageView mySecondImage = (ImageView) findViewById(R.id.mySecondImage);
ImageView myThirdImage = (ImageView) findViewById(R.id.myThirdImage);
String URL1 = "http://www.google.com/logos/2013/estonia_independence_day_2013-1057005.3-hp.jpg";
String URL2 = "http://www.google.com/logos/2013/park_su-geuns_birthday-1055005-hp.jpg";
String URL3 = "http://www.google.com/logos/2013/anne_cath_vestlys_93rd_birthday-1035005-hp.jpg";
myFirstImage.setTag(URL1);
mySecondImage.setTag(URL2);
myThirdImage.setTag(URL3);
new DownloadImageTask.execute(myFirstImage);
new DownloadImageTask.execute(mySecondImage);
new DownloadImageTask.execute(myThirdImage);
public class DownloadImagesTask extends AsyncTask<ImageView, Void, Bitmap> {
ImageView imageView = null;
#Override
protected Bitmap doInBackground(ImageView... imageViews) {
this.imageView = imageViews[0];
return download_Image((String)imageView.getTag());
}
#Override
protected void onPostExecute(Bitmap result) {
imageView.setImageBitmap(result);
}
private Bitmap download_Image(String url) {
Bitmap bmp =null;
try{
URL ulrn = new URL(url);
HttpURLConnection con = (HttpURLConnection)ulrn.openConnection();
InputStream is = con.getInputStream();
bmp = BitmapFactory.decodeStream(is);
if (null != bmp)
return bmp;
}catch(Exception e){}
return bmp;
}
}

you can create a class say..BkgProcess which contains an inner class that extends AsyncTask. while instantiating BkgProcess pass the context of your Activity class in BkgProcess constructor. for eg:
public class BkgProcess {
String path;
Context _context;
public Download(Downloader downloader, String path2){
this.path = path2;
_context = downloader;
}
public void callProgressDialog(){
new BkgProcess().execute((Void)null);
}
class Downloads extends AsyncTask<Void, Void, Boolean> {
private ProgressDialog dialog = new ProgressDialog(_context);
protected void onPreExecute(){
dialog.setMessage("Downloading image..");
dialog.show();
}
protected void onPostExecute(Boolean success) {
dialog.dismiss();
if(success)
Toast.makeText(_context, "Download complete", Toast.LENGTH_SHORT).show();
}
#Override
protected Boolean doInBackground(Void... params) {
return(startDownload(path));
}
public boolean startDownload(String img_url) {
// download img..
return true;
}
}
}
from your activity class..
BkgProcess dwn = new BkgProcess (Your_Activity_class.this, img_path);
dwn.callProgressDialog();

This will get you images of any size...
if you dont want the progress dialog just comment the codes in onPreExecute();
for(int i = 0 ; i < no_of_files ; i++ )
new FetchFilesTask().execute(image_url[i]);
private class FetchFilesTask extends AsyncTask<String, Void, Bitmap> {
private ProgressDialog dialog = new ProgressDialog(FileExplorer.this);
Bitmap bitmap[];
protected void onPreExecute(){
dialog.setMessage("fetching image from the server");
dialog.show();
}
protected Bitmap doInBackground(String... args) {
bitmap = getBitmapImageFromServer();
return bitmap;
}
protected void onPostExecute(Bitmap m_bitmap) {
dialog.dismiss();
if(m_bitmap != null)
//store the images in an array or do something else with all the images.
}
}
public Bitmap getBitmapImageFromServer(){
// fetch image form the url using the URL and URLConnection class
}