实现 Adapter 的 getView 效率提高

本文主要是介绍实现 Adapter 的 getView 效率提高，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

Adapter

显示每条数据的 XML 布局文件
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal">
<ImageView android:id="@+id/icon"
android:layout_width="48dip"
android:layout_height="48dip" />
<TextView android:id="@+id/text"
android:layout_gravity="center_vertical"
android:layout_width="0dip"
android:layout_weight="1.0"
android:layout_height="wrap_content" />
</LinearLayout>

滚动时, 频繁调用

public View getView(int pos, View convertView,
ViewGroup parent){
View item = mInflater.inflate(R.layout.list_item, null);
((TextView) item.findViewById(R.id.text)).
setText(DATA[pos]);
((ImageView) item.findViewButId(R.id.icon)).
setImageBitmap((pos & 1) == 1 ? mIcon1 : mIcon2);
return item;
}
..简单的方法, 最慢最不实用

..利用convertView回收视图

public View getView(int pos, View convertView,
ViewGroup parent){
if (convertView == null) {
convertView = mInflater.inflate(
R.layout.list_item, null);
}
((TextView) convertView.findViewById(R.id.text)).
setText(DATA[pos]);
((ImageView) convertView.findViewButId(R.id.icon)).
setImageBitmap((pos & 1) == 1 ? mIcon1 : mIcon2);
return convertView;
}
..................................再度优化, 效率提高 200%

static class ViewHolder {
TextView text;
ImageView icon;
}

public View getView(int pos, View convertView, ViewGroup parent){
ViewHolder holder;
if (convertView == null) {
convertView = mInflater.inflate(R.layout.list_item, null);
holder = new ViewHolder();
holder.text = (TextView) convertView.findViewById(
R.id.text));
holder.icon = (ImageView) convertView.findViewButId(
R.id.icon));
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
holder.text.setText(DATA[pos]);
holder.icon.setImageBitmap((pos & 1) == 1 ? mIcon1 : mIcon2);
return convertView;
}