@Override
 public boolean onOptionsItemSelected(MenuItem item) {
   switch (item.getItemId()) {
     case R.id.col1:
       mGridView.setColumnCount(1);
       break;
     case R.id.col2:
       mGridView.setColumnCount(2);
       break;
     case R.id.col3:
       mGridView.setColumnCount(3);
       break;
   }
   return true;
 }