Question

i am trying to show the progress dialog in my program when press the refresh button but the application close unexpexted with error in debugger that the thread which one is created ui hierachy can only touch it.

    public class MainActivity extends Activity {
    Handler handler = new Handler();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        this.refreshView();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }

    public void refreshView(){
        ImageView img = (ImageView) findViewById(R.id.imageView1);
        Bitmap bm = null;
        InputStream is = null;
        BufferedInputStream bis = null;
        try 
        {
            URLConnection conn = new URL("http://technomoot.edu.pk/$Common/Image/Content/ciit_logo.jpg").openConnection();
            conn.connect();
            is = conn.getInputStream();
            bis = new BufferedInputStream(is, 8192);
            bm = BitmapFactory.decodeStream(bis);
        }
        catch (Exception e) 
        {
            e.printStackTrace();
        }
        finally {
            if (bis != null) 
            {
                try 
                {
                    bis.close();
                }
                catch (IOException e) 
                {
                    e.printStackTrace();
                }
            }
            if (is != null) 
            {
                try 
                {
                    is.close();
                }
                catch (IOException e) 
                {
                    e.printStackTrace();
                }
            }
        }
        img.setImageBitmap(bm);
}

    public void onRefresh(View view) {

        final ProgressDialog dialog = ProgressDialog.show(this,"Loading","Loading the image of the Day");
        Thread th = new Thread(){
            public void run(){
                refreshView();
                handler.post(new Runnable(){
                    public void run(){
                        dialog.dismiss();
                    }
                }
                        );
            }

        };th.start();   
    }

}

Answer 1

You can’t manipulate with UI from worker Thread! It’s prohibited! If you want to update UI just use

• runOnUiThread()
• AsyncTask

So try it like this:

runOnUiThread(new Runnable() {

   @Override
   public void run() {
      // do your work.

   }
});

AsyncTask is more complex, also generic-type that provides some benefits like type control etc. You can look at example here:

• Android application (performance and more) analysis tools -
Tutorial