Question

I have this code that pulls an image from an url and displays it within the app.

    Drawable drawableTest = LoadImageFromWeb("http://www.someimageurl");
    imgView.setImageDrawable(drawableTest);

private Drawable LoadImageFromWeb(String url){
    try {
        InputStream is = (InputStream) new URL(url).getContent();
        Drawable d = Drawable.createFromStream(is, "src name");
        return d;
    }catch (Exception e) {
        System.out.println("Exc="+e);
        return null;
    }
 }

The method works and the image is pulled into the app without a problem. What I’d like to do is two things…

1) Move the process to a background thread.

2) Display a “loading” drawable (located in drawable folder) while the image is being downloaded and then switch to image when done. If there’s a problem I’d like to load a “unable to load image” drawable (also located in drawable folder).

Can someone help modify the method above so that it will run in the background and display the appropriate images upon loading and if there’s a problem?

Thanks! You guys rock btw.

Shannon

Answer 1

You can use AsyncTask to run the task in another thread. That way, it won’t block UI. Roughly, it should be something like this:

private class MyTask extends AsyncTask<String, Void, Drawable> {

     ProgressDialog pd;

     protected Drawable doInBackground(String... url) {
            try {
                pd = ProgressDialog.show(this, "Working..", "Getting image", true, false);
                InputStream is = (InputStream) new URL(url[0]).getContent();
                Drawable d = Drawable.createFromStream(is, "src name");
                return d;
            } catch (Exception e) {
                System.out.println("Exception = " + e);
                return null;
            }
     }

     protected void onProgressUpdate(Void... progress) {
     }

     protected void onPostExecute(Drawable result) {
         /* Image loaded...*/
         pd.dismiss();
         imgView.setImageDrawable(result);

     }
}

MyTask task = new MyTask();
task.execute("http://www.someimageurl");

You can change the ProgressDialog with whatever you like…