로딩화면 띄우기

..extends Activity
{

  ..

  private ProgressDialog mProgressDialog = null;

  ..onCreate(..)
  {

    ..
    mProgressDialog = new ProgressDialog(this);
    mProgressDialog = ProgressDialog.show(ctx,"로딩", "로딩중.", true);
    //로딩화면 띄운 동안 할것
    runOnUiThread(returnRes);

  }

  ..

  private Runnable returnRes = new Runnable()
 {
  @Override
  public void run()
  {
   mProgressDialog.dismiss();
  }
 };