Question

I have a layout with about 20 horizontal progress bars. Each of them is for separate picture to download. I am checking CheckBoxes to show which pictures to download. Downloading starts when “DOWNLOAD” button is pressed. How to make downloading of few pictures at the same time and how to update progress bars?

Answer 1

Write an async to do your downloading task.
in async task you can download you file in doinbackground() also you publish the progress their using
publishProgress(int);
in the same async task you also have below method.

@Override
protected void onProgressUpdate(Void... values) {
    // TODO Auto-generated method stub
    super.onProgressUpdate(values);
//here comes your code to set progress
progressBar.setProgress(values[0]);
}

so on click event you execute the asynctask by below lines:

new YourAsyncTask().execute();

Thats all…. also have a look below urls

There are plenty of articles on asynctasks. Some of them I am mentioning here: http://developer.android.com/reference/android/os/AsyncTask.html http://www.vogella.de/articles/AndroidPerformance/article.html http://androidpartaker.wordpress.com/2010/08/01/android-async-task/ http://android10.org/index.php/articlesother/239-android-application-and-asynctask-basics

and so on. First brush up your async task concepts and start implementing them. This will surely resolve your query.