43、gridview或者listview的adapter优化

1、在getview时，如果是一个textview，那么不用每次都new一个或者inflater直接返回，可以先判断convertview是否为空，如果为空则new或者inflate，否则直接返回convertview

2、如果adapter数量太多，假设需要显示1000个数据，那么如果在getview时每次都是对inflate，那么是一种对资源的浪费，且卡顿现象严重，此时可以通过结合viewHolder提高效率

举例：

1、adapter的getview方法

@Override
    public View getView( int pos, View convertView, ViewGroup parent) {
        // TODO Auto-generated method stub

            ViewHolderPushHistory holder;
            final int position = pos;

            if(convertView == null)
            {

                CommonUtils.LogWuwei(tag, "pushHistoryAdapter  getView position is "+pos);

                LayoutInflater inflater = (LayoutInflater)ctxt.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

                holder = new ViewHolderPushHistory();

                convertView = inflater.inflate(R.layout.gridview_history_item, null);

                holder.tv_serinal_num = (TextView)convertView.findViewById(R.id.textview_grdiview_history_item_serinal_num);

                holder.tv_whether_packaged = (TextView)convertView.findViewById(R.id.textview_grdiview_history_item_whether_packaged);

                holder.buttonContent = (TextView)convertView.findViewById(R.id.button_gridview_history_item_order_content);

                holder.buttonTime = (TextView)convertView.findViewById(R.id.textview_grdiview_history_item_time);

                convertView.setTag(holder);
            }
            else
            {
                holder = (ViewHolderPushHistory)convertView.getTag();
            }

            holder.tv_serinal_num.setText(serinal_num);

            holder.buttonContent.setText("鱼香肉丝");

            holder.tv_whether_packaged.setText("打包");                

            holder.buttonTime.setText(“2：12”）;

            return convertView;

    }

2、定义一个存储信息的类

 package com.shanfubaoAndroid.kitchenMealDone;

 import android.widget.TextView;

 public class ViewHolderPushHistory {

     public TextView tv_serinal_num;

     public TextView tv_whether_packaged ;

     public TextView buttonContent ;

     public TextView buttonTime ;

 }