gridview setNotifiedDataSetChanged() not updating gridview smoothly?

I try to update gridview background color smoothly but it does not work somoothly. when i scrool gridview at that 开发者_如何学JAVAtime it get changed; plz guide me how to do it, below is my code, Thanks you.

TableGridViewAdapter gridadapter;
 GridView gridview;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState); 

            textViewUname = (TextView) this.findViewById(R.id.userName);
            textViewUname.setText("Welcome , " + HomeActivity.name);

             gridview = (GridView) findViewById(R.id.gridview);
             gridadapter=new TableGridViewAdapter(this);
             gridview.setAdapter(gridadapter);
            //adapter.notifyDataSetChanged();            

             UpdateGridview updateGridview=new UpdateGridview();
             updateGridview.execute(TableActivity.this);



            // code for onClick gridview items , It take to that Activity
            gridview.setOnItemClickListener(new OnItemClickListener() {

                @Override
                public void onItemClick(AdapterView<?> parent, View v,
                        int position, long id) {
                    ConText.currentPos = position;
                    Intent i = new Intent(TableActivity.this,
                            OrderListActivity.class);
                    i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK
                            | Intent.FLAG_ACTIVITY_CLEAR_TOP);
                    startActivity(i);
                    finish();

                }

            });
        } 
    }

}

here i tryed to refreshing view in every 20sec

  private class UpdateGridview extends AsyncTask<Context, Integer, String>
       {    
        @Override
        protected String doInBackground( Context... params ) 
        {

                int i = 0;
                while( i <10) 
                {
                        try{

                               gridadapter.notifyDataSetChanged();
                              // gridadapter.refreshItems(gridadapter);
                               gridview.invalidate();

                              //TableGridViewAdapter.refreshItems(gridadapter);
                               Thread.sleep( 20000 );
                               System.out.println("i  called notifyDataSetChanged()=======================");
                                i++;
                        } catch( Exception e ){
                                Log.i("makemachine", e.getMessage() );
                        }
                }
                return "COMPLETE!";
        }

// -- gets called just before thread begins
        @Override
        protected void onPreExecute() 
        {
                Log.i( "makemachine", "onPreExecute()" );
                super.onPreExecute();

        }


        @Override
        protected void onProgressUpdate(Integer... values) 
        {
                super.onProgressUpdate(values);

        }

        // -- called if the cancel button is pressed
        @Override
        protected void onCancelled()
        {
                super.onCancelled();
               Log.i( "makemachine", "onCancelled()" );

        }

        // -- called as soon as doInBackground method completes
        // -- notice that the third param gets passed to this method
        @Override
        protected void onPostExecute( String result ) 
        {
                super.onPostExecute(result);
                Log.i( "makemachine", "onPostExecute(): " + result );

        }

}

}

Try like this:

private final Handler handler = new Handler() {
        public void handleMessage(Message msg) {
            if(msg.arg1 == 1){
                gridadapter.notifyDataSetChanged();
            }
        }   
   };



private class UpdateGridview extends AsyncTask<Context, Integer, String>
       {    
        @Override
        protected String doInBackground( Context... params ) 
        {

                int i = 0;
                while( i <10) 
                {
                        try{

                              // gridadapter.notifyDataSetChanged();
                              // gridadapter.refreshItems(gridadapter);
                               //gridview.invalidate();
                                 Message msg = handler.obtainMessage();
                                 msg.arg1 = 1;
                                 handler.sendMessage(msg);
                              //TableGridViewAdapter.refreshItems(gridadapter);
                               Thread.sleep( 20000 );
                               System.out.println("i  called notifyDataSetChanged()=======================");
                                i++;
                        } catch( Exception e ){
                                Log.i("makemachine", e.getMessage() );
                        }
                }
                return "COMPLETE!";
        }

// -- gets called just before thread begins
        @Override
        protected void onPreExecute() 
        {
                Log.i( "makemachine", "onPreExecute()" );
                super.onPreExecute();

        }


        @Override
        protected void onProgressUpdate(Integer... values) 
        {
                super.onProgressUpdate(values);

        }

        // -- called if the cancel button is pressed
        @Override
        protected void onCancelled()
        {
                super.onCancelled();
               Log.i( "makemachine", "onCancelled()" );

        }

        // -- called as soon as doInBackground method completes
        // -- notice that the third param gets passed to this method
        @Override
        protected void onPostExecute( String result ) 
        {
                super.onPostExecute(result);
                Log.i( "makemachine", "onPostExecute(): " + result );

        }
}

}