Question

I just wanted to Grab an image from a URL and to display it in an imageview

The code:

public class MainActivity extends Activity {

    // declare internal using controls
    private TextView txtUrl;
    private ImageView imgView;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        imgView =(ImageView)findViewById(R.id.imageView1);

        Drawable drawable=null;


            drawable = grabImageFromUrl("http://blog.sptechnolab.com/wp-content/uploads/2011/02/c2.jpg");
            imgView.setImageDrawable(drawable);

    }



    private Drawable grabImageFromUrl(String url)  {
        try {
            return Drawable.createFromStream((InputStream)new URL(url).getContent(), "src");
        } catch (MalformedURLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;
    }

}

I am having this error:

09-04 20:34:18.712: E/AndroidRuntime(1156): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.test/com.example.test.MainActivity}: android.os.NetworkOnMainThreadException

I would appreciate your help please be specific in your answers

Answer 1

Is your app configured with Internet permissions? That is, do you have the following in your app’s manifest?

    <uses-permission android:name="android.permission.INTERNET" />

FOLLOW UP: Also, the error seems to be saying you shouldn’t do network access on your app’s UI thread. It’s generally a bad practice to do any long blocking I\O on your app’s UI thread. Try using an AnycTask, or you might even have a look at some of the code in LazyList.

EXAMPLE: add this as an inner class to your activity:

private class DownloadTask extends AsyncTask<Void, Void, Drawable>{

    private final String mUrl;
    public DownloadTask(String url){
        mUrl = url;
    }

    @Override
    protected Drawable doInBackground(Void... params) {
        try {
            return Drawable.createFromStream((InputStream)new URL(mUrl).getContent(), "src");
        } catch (MalformedURLException e) {
            e.printStackTrace();
            return null;
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }
    }

    @Override
    protected void onPostExecute(Drawable result){
        ((ImageView)findViewById(R.id.imageView1)).setImageDrawable(result);
    }

}

Then call it like this from your onCreate:

new DownloadTask(url).execute();