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LEVEL: Beginner
Language: Java
IDE: Android Studio
CASE: Downloading multiple MP3 files from multiple URL's in a row in the background.
ISSUE: download task in the loop to download all the urls. the songs did download in the following path but aren't fully downloaded (every song is downloaded for 3 seconds/4 seconds basically very less). don't know what's the problem, It'll be great if i can get any help

  • receive mp3 url's from API
  • download them using the following code. (ISSUE)
  • get the path of all and store them in the Database

  • fetch the path and play one by one continuously.

    private class DownloadTask extends AsyncTask<SongDetails, Integer, String> {
Context context;

public DownloadTask(Context context) {
    this.context = context;
}

@Override
protected void onPreExecute() {
    super.onPreExecute();
    Utilities.showProgressDialog(getActivity(), getFragmentManager());
}

@Override
protected String doInBackground(SongDetails... songDetails) {
    for (SongDetails songs : songDetails
    ) {
        donwloadsong(songs);
    }
    return null;
}

@Override
protected void onPostExecute(String s) {
    super.onPostExecute(s);
    Utilities.dismissProgressDialog();
}
}




 for (SongDetails songs : songDetails
    ) {
        downloadTask(songs);
    }


 public void downloadTask(SongDetails songs){
   HttpURLConnection httpURLConnection = null;
   try {
     URL url = new URL(songs.getUrl());
     httpURLConnection = (HttpURLConnection) url.openConnection();
     httpURLConnection.setRequestMethod("GET");
     httpURLConnection.connect();

    int fileLength = httpURLConnection.getContentLength();
         InputStream inputStream = new 
    BufferedInputStream(url.openStream(), 8192);
    OutputStream outputStream1;
    outputStream1 = new 
    FileOutputStream(Environment.getExternalStorageDirectory() + "/gbeduwarssongs/" + songDetails.getTitle().trim() + ".mp3");
    int count = 0;
         byte data[] = new byte[1024];
    int buffer_length;

    while ((buffer_length = inputStream.read(data)) != -1) {
        outputStream1.write(data, 0, count);
          count += buffer_length;
    }
    outputStream1.flush();
    outputStream1.close();
    inputStream.close();

} catch (Exception e) {
    e.printStackTrace();
    Log.e("Error", "Download Error Exception " + e.getMessage());
} finally {
    if (httpURLConnection != null)
        httpURLConnection.disconnect();
  }
}
Honey
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  • can you post more code i mean complete actitivity code.. – Abdul Waheed Apr 04 '19 at 12:27
  • If you expect the download to last longer than a couple of seconds, then I'd suggest you use something other than `AsyncTask`, which is really only suitable for short off-UI-thread work. A Foreground `Service` perhaps, or maybe `DownloadManager` – PPartisan Apr 04 '19 at 12:30
  • Sure i'll update the code @AbdulWaheed – Honey Apr 04 '19 at 12:31
  • DownloadManager notifies the user in the notification section if am not wrong, I don't want user to know what's happening in the background @PPartisan Also i'll try with Foreground Service – Honey Apr 04 '19 at 12:32
  • DownloadManager did the work. Thankyou – Honey Apr 09 '19 at 08:29
  • DownloadManager doesn't work below Nougat. Could you tell me what could i use for lower level API's @PPartisan – Honey Apr 17 '19 at 05:56
  • [`DownloadManager`](https://developer.android.com/reference/android/app/DownloadManager) is compatible with Android Gingerbread and up – PPartisan Apr 17 '19 at 06:39
  • I got it yesterday, i was adding a method named setRequiresCharging(false) which needed API 24 in DownloadManager. Thank you for your revert :) @PPartisan – Honey Apr 18 '19 at 08:19

2 Answers2

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Rather calling iteration inside a new thread, use iteration first and then start new thread in every iteration. I hope it will help you. I am posting code for your help.

for (SongDetails songs : songDetails) {
        new DownloadTask(pass your song object in constructor).executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
    }

and in doInBackground call your downloading method stuff.

Abdul Waheed
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  • Tried this, but i got an Error: Cannot execute task: the task is already running. Also AsyncTask can only be executed once as i searched the error. So iterating it did not go well. @AbdulWaheed – Honey Apr 04 '19 at 13:58
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I offer to use DownloadManager or workmanager for it. AsyncTask has used a bad idea. It has a problem with a memory leak. The asyncTask use only one thread

The same question

Alexander
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