BaseAdapter的getView有关问题

    public View getView(int position, View convertView, ViewGroup parent) {        Log.i(TAG, "getView -- " + position + " -- " + convertView);                ViewHolder holder = null;        if(convertView == null){            convertView = mInflater.inflate(R.layout.list_item, null);            holder = new ViewHolder();            holder.ivPic = (ImageView) convertView.findViewById(R.id.iv_pic);            holder.tvTitle = (TextView) convertView.findViewById(R.id.tv_title);            holder.cbSelect = (CheckBox) convertView.findViewById(R.id.cb_selected);            holder.btOk    = (Button) convertView.findViewById(R.id.btn_ok);                        convertView.setTag(holder);        } else{            holder = (ViewHolder) convertView.getTag();        }                convertView.setOnClickListener(new OnClickListener() {                        public void onClick(View v) {//                viewHolder.cbSelect.toggle();                Log.i(TAG, "click the convertView at ");            }        });                holder.btOk.setOnClickListener(new OnClickListener() {                        public void onClick(View v) {                Log.i(TAG, "click the button");            }        });                holder.ivPic.setBackgroundResource(list.get(position).getPicId());        holder.tvTitle.setText(list.get(position).getTitle());                return convertView;    }