Develop Reference

how to get the return value from my doInBackground task?

I'm new on android studio and I'm trying to do an AsyncTask for my Network operation.
The problem is to get the return variable from it to be able to set the image in the imageview. imgDisplay.setImageBitmap(var)
public class ZoomActivity extends Activity {
#SuppressLint("NewApi")
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_zoom);
Intent intent = getIntent();
String url2 = intent.getStringExtra("image");
ImageView imgDisplay;
Button btnClose;
imgDisplay = (ImageView) findViewById(R.id.imgDisplay);
btnClose = (Button) findViewById(R.id.btnClose);
//Bitmap var = return of doInBackground??????????
imgDisplay.setImageBitmap(var);
btnClose.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
ZoomActivity.this.finish();
}
});
}
private class MyTask extends AsyncTask<String, Integer, String> {
#Override
protected String doInBackground(String... Params) {
String myString = Params[0];
try {
URL url = new URL(URL???); //how to pass url2 var here?
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;
}
}
}
}
any examples?

First, declare this asynctask class:
class MyTask extends AsyncTask<String,Void,Bitmap>{
#Override
protected Bitmap doInBackground(String... strings) {
String myString = Params[0];
try {
URL url = new URL(myString);
Bitmap myBitmap = BitmapFactory.decodeStream(url.openConnection().getInputStream());
return myBitmap;
} catch (IOException e) {
e.printStackTrace();
return null;
}
return null;
}
#Override
protected void onPostExecute(Bitmap bitmap) {
super.onPostExecute(bitmap);
imgDisplay.setImageBitmap(bitmap);
}
}
Your zoomActivity changes to:
public class ZoomActivity extends Activity {
ImageView imgDisplay;
#SuppressLint("NewApi")
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_zoom);
Intent intent = getIntent();
String url2 = intent.getStringExtra("image");
Button btnClose;
imgDisplay = (ImageView) findViewById(R.id.imgDisplay);
btnClose = (Button) findViewById(R.id.btnClose);
//call asynctask
new MyTask().execute(url2);
btnClose.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
ZoomActivity.this.finish();
}
});
}
hope this works

When your doInBackground returns an object, it goes to the method onPostExecute as an input parameter, and that method executes in the UI thread and not a parallel thread, so you can set the imag

AsyncTask
This this for reference.
Change you MyTask to
private class MyTask extends AsyncTask<String, Integer, BitMap> {
#Override
protected Bitmap doInBackground(String... Params) {
String myString = Params[0];
try {
URL url = new URL(URL???); //how to pass url2 var here?
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;
}
}
protected void onPostExecute(Bitmap result) {
//set the Image here.
imgDisplay.setImageBitmap(result);
}
}

You should let the AsyncTask return a Bitmap instead of a String
private class MyTask extends AsyncTask<String, Integer, Bitmap> {
#Override
protected Bitmap doInBackground(String... Params) {
String myString = Params[0];
try {
URL url = new URL(myString); //how to pass url2 var here?
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;
}
}
protected void onPostExecute(Bitmap result) {
//set your bitmap here to your imgDisplay
}
}
Then you start the task with
new MyTask().execute(/* urlString*/)

Android AsyncTask wait until Status.FINISHED

Well I am downloading a image from url with AsyncTask,
I want to show this image in dialog, right after image downloaded.
I m trying with this code: It ıs not waiting until finish, this code is returning RUNNING.
if(dt.getStatus() == AsyncTask.Status.FINISHED) {
dialog.show();
}

You need to set an event listener. Just setting an if-then statement means it will be executed the moment it finds the code. A event listener will wait until the event happens (In this case, Status.FINISHED) and then execute the code inside the listener.

With Ken Wolf helps..
public class DownloadImageTask extends AsyncTask<String, Void, Bitmap> {
ImageView bmImage;
private Context mcontec;
public DownloadImageTask(ImageView bmImage, Context mContextr) {
this.bmImage = bmImage;
mcontec=mContextr;
}
protected Bitmap doInBackground(String... urls) {
String urldisplay = urls[0];
Bitmap mIcon11 = null;
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) {
dialog(result, mcontec);
}
public void dialog(Bitmap resim, final Context ctx){
final Dialog dialog = new Dialog(ctx, R.style.CustomDialogTheme);
dialog.setContentView(R.layout.perdereklam);
ImageView reklam = (ImageView) dialog.findViewById(R.id.reklampng);
reklam.setImageBitmap(resim);
reklam.setOnTouchListener(new OnTouchListener() {
// fill your stuff...
}
dialog.show();
}
calling from any class:
public static void showRateDialog(final Context mContextr) {
final Dialog dialog = new Dialog(mContextr, R.style.CustomDialogTheme);
ImageView reklam = (ImageView) dialog.findViewById(R.id.reklampng);
final DownloadImageTask dt = new DownloadImageTask(reklam, mContextr);
dt.execute("your url");
}

Load two images from url to imageviews

when I tried to load only one image from url, it is working, but when I tried to load two images, it's just loading the last image.
This is what I've tried so far:
ProgressDialog pd;
private ImageView imgView1, imgView2;
private String strURLJohnA = "sample1.jpg";
private String strURLJohnR = "sample2.jpg";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.info);
back = (Button) findViewById (R.id.btBack);
back.setOnClickListener(this);
imgView1 = (ImageView) findViewById(R.id.ivInfo1);
imgView2 = (ImageView) findViewById (R.id.ivInfo2);
// Create an object for subclass of AsyncTask
GetXMLTask task = new GetXMLTask();
// Execute the task
task.execute(new String[] { strURLJohnA, strURLJohnR });
}
private class GetXMLTask extends AsyncTask<String, Void, Bitmap> {
#Override
protected Bitmap doInBackground(String... urls) {
Bitmap map = null;
for (String url : urls) {
map = downloadImage(url);
}
return map;
}
#Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
pd = ProgressDialog.show(Info.this, "Please wait", "Downloading content", false, true);
}
// Sets the Bitmap returned by doInBackground
#Override
protected void onPostExecute(Bitmap result) {
imgView1.setImageBitmap(result);
imgView2.setImageBitmap(result);
pd.dismiss();
}
// Creates Bitmap from InputStream and returns it
private Bitmap downloadImage(String url) {
Bitmap bitmap = null;
InputStream stream = null;
BitmapFactory.Options bmOptions = new BitmapFactory.Options();
bmOptions.inSampleSize = 1;
try {
stream = getHttpConnection(url);
bitmap = BitmapFactory.
decodeStream(stream, null, bmOptions);
stream.close();
} catch (IOException e1) {
e1.printStackTrace();
}
return bitmap;
}
// Makes HttpURLConnection and returns InputStream
private InputStream getHttpConnection(String urlString)
throws IOException {
InputStream stream = null;
URL url = new URL(urlString);
URLConnection connection = url.openConnection();
try {
HttpURLConnection httpConnection = (HttpURLConnection) connection;
httpConnection.setRequestMethod("GET");
httpConnection.connect();
if (httpConnection.getResponseCode() == HttpURLConnection.HTTP_OK) {
stream = httpConnection.getInputStream();
}
} catch (Exception ex) {
ex.printStackTrace();
}
return stream;
}
}
Any ideas how to resolve the issue? I'd greatly appreciate your help. Thanks.

You a list instead as follows:
private class GetXMLTask extends AsyncTask<String, Void, ArrayList<Bitmap>> {
#Override
protected ArrayList<Bitmap> doInBackground(String... urls) {
ArrayList<Bitmap> map = new ArrayList<Bitmap>();
for (String url : urls) {
map.add(downloadImage(url));
}
return map;
}
#Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
pd = ProgressDialog.show(Info.this, "Please wait", "Downloading content", false, true);
}
// Sets the Bitmap returned by doInBackground
#Override
protected void onPostExecute(ArrayList<Bitmap> result) {
imgView1.setImageBitmap(result.get(0));
imgView2.setImageBitmap(result.get(1));
pd.dismiss();
}
...
...
...
You need to return a list of Bitmap objects like I have shown in the code above. Then set the imageView to its respective bitmap.

(String... urls) is Var args. You dont need to pass a string array to it. Use as following code:
task.execute( strURLJohnA, strURLJohnR );
private class GetXMLTask extends AsyncTask<String, Void, ArrayList<Bitmap>> {
#Override
protected ArrayList<Bitmap> doInBackground(String... urls) {
ArrayList<Bitmap> map = new ArrayList<Bitmap>();
map.add(downloadImage(urls[0]));// I used as this for you to understand. You can use for each loop
map.add(downloadImage(urls[1]));
return map;
}
#Override
protected void onPostExecute(ArrayList<Bitmap> result) {
imgView1.setImageBitmap(result.get(0));
imgView2.setImageBitmap(result.get(1));
}

ProgressDialog pd;
private ImageView imgView1, imgView2;
//we can store any number of urls in a string array and load them at a time
private String[] str={"http://www.bogotobogo.com/images/rodin.jpg","http://www.bogotobogo.com/images/smalltiger.gif"};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
imgView1=(ImageView)findViewById(R.id.imageView1);
imgView2=(ImageView)findViewById(R.id.imageView2);
// Create an object for subclass of AsyncTask
GetXMLTask task = new GetXMLTask ();
// Execute the task
task.execute(str);
}
private class GetXMLTask extends AsyncTask<String, Void, ArrayList<Bitmap>> {
#Override
protected ArrayList<Bitmap> doInBackground(String... urls) {
ArrayList<Bitmap> map = new ArrayList<Bitmap>();
//enhanced for statement, mainly used for arrays
for (String url : urls) {
map.add(downloadImage(url));
}
return map;
}
#Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
pd = ProgressDialog.show(Info.this, "Please wait", "Downloading content", false, true);
}
// Sets the Bitmap returned by doInBackground
#Override
protected void onPostExecute(ArrayList<Bitmap> result) {
imgView1.setImageBitmap(result.get(0));
imgView2.setImageBitmap(result.get(1));
pd.dismiss();
}

Parsing Image URL Android

I have parsed several items of weather data from an online xml file. One of the nodes is a URL of an image I want to display. I have managed to parse it and save it as a String variable and it displays in the app as a String. How do I get it to display the image instead of text?
Thanks in advance!

First, you need to download the image and store it in a Bitmap object.
Then, display it with an ImageView.
This answer describes how you can do it in some detail.

public class MainActivity extends Activity {
ProgressDialog pd;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
pd = new ProgressDialog(MainActivity.this);
pd.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
new DownloadImageTask((ImageView) findViewById(R.id.imageView1))
.execute("Your URL");
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
class DownloadImageTask extends AsyncTask<String, Void, Bitmap> {
ImageView bmImage;
DownloadImageTask(ImageView bmImage) {
this.bmImage = bmImage;
}
#Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
pd = new ProgressDialog(MainActivity.this);
pd.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
}
protected Bitmap doInBackground(String... urls) {
String urldisplay = urls[0];
Bitmap mIcon11 = null;
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) {
pd.dismiss();
bmImage.setImageBitmap(result);
}
}
}

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
}