问每次数据更改时更新ListView

EN

@Override
protected void onPostExecute(Void result) {
    super.onPostExecute(result);


    // Dismiss the progress dialog
    if (pDialog.isShowing())
        pDialog.dismiss();
    /**
     * Updating parsed JSON data into ListView
     * */


    adapter =  new costumeadapter(
                    ChatRoomActivity.this,
                    contactList,
                    R.layout.chat_row,
                    new String[]{ TAG_MESSAGE, TAG_CONVERSATION },
                    new int[]{ R.id.name, R.id.conversationid });

    setListAdapter(adapter);

}

public View getView(int position, View convertView, ViewGroup parent){

      View v = super.getView(position, convertView, parent);


      TextView text = (TextView) v.getTag();

      if(text == null){
         text = (TextView) v.findViewById(R.id.name);
          v.setTag(text);
      } 

     String pos = (String) ((Map)getItem(position)).get(TAG_POSITION);

     text.setBackgroundResource(pos.equals("left") ? R.drawable.bubble_green : R.drawable.bubble_yellow);

     conversationid = (TextView)v.findViewById(R.id.conversationid);

     send.setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {

            String getmessage = txtmessage.getText().toString();
            String getconversationid = conversationid.getText().toString();

            SendMessage mTask = new SendMessage();
            mTask.execute(sessionid,getmessage,getconversationid);

            adapter.notifyDataSetChanged();
         }
     });

      return v;  

   }