如何高效使用Adapter

最新推荐文章于 2025-02-11 12:47:55 发布

转载最新推荐文章于 2025-02-11 12:47:55 发布 · 690 阅读

文章标签：

#listview #null #function

Android 专栏收录该内容

63 篇文章

订阅专栏

本文介绍了在Android开发中ListView的三种getView实现方法，详细对比了不同版本的性能差异，并推荐使用ViewHolder模式来提高ListView滚动效率。

以下转自How you create your view for listview on Android?

How you create your view for listview on Android?
There have three versions of getView() function,
the first version is a slow way,and the last is the fastest one.

Version 1:

 
    1public View getView(int position, View convertView, ViewGroup parent) {
 
    2     View item = mInflater.inflate(R.layout.list_item_icon_text, null);
 
    3      ((TextView) item.findViewById(R.id.text)).setText(DATA[position]);
 
    4      ((ImageView) item.findViewById(R.id.icon)).setImageBitmap(
 
    5     (position & 1) == 1 ? mIcon1 : mIcon2);
 
    6      return item;
 
    7 }

Version 2:

 
    1public View getView(int position, View convertView, ViewGroup parent) {
 
    2    if (convertView == null) {
 
    3      convertView = mInflater.inflate(R.layout.item, parent, false);
 
    4    }
 
    5    ((TextView) convertView.findViewById(R.id.text)).setText(DATA[position]);
 
    6     ((ImageView) convertView.findViewById(R.id.icon)).setImageBitmap(
 
    7     (position & 1) == 1 ? mIcon1 : mIcon2);
 
    8     return convertView;
 
    9 }

Version 3: the fast way for getView function.

 
    01static class ViewHolder {
 
    02  TextView text;
 
    03  ImageView icon;
 
    04}
 
    05 
 
    06public View getView(int position, View convertView, ViewGroup parent) {
 
    07   ViewHolder holder;
 
    08 
 
    09  if (convertView == null) {
 
    10     convertView = mInflater.inflate(R.layout.list_item_icon_text,parent, false);
 
    11     holder = new ViewHolder();
 
    12     holder.text = (TextView) convertView.findViewById(R.id.text);
 
    13     holder.icon = (ImageView) convertView.findViewById(R.id.icon);
 
    14     convertView.setTag(holder);
 
    15   } else {
 
    16     holder = (ViewHolder) convertView.getTag();
 
    17   }
 
    18 
 
    19   holder.text.setText(DATA[position]);
 
    20   holder.icon.setImageBitmap((position & 1) == 1 ? mIcon1 : mIcon2);
 
    21   return convertView;
 
    22 
 
    23}