android– 自定义listView中的持有者是如何创建的？

概述我在以下链接中看到了自定义列表视图的程序http://www.ezzylearning.comutorial.aspx?tid=1763429&q=customizing-android-listview-items-with-custom-arrayadapter这是定制适配器：publicclassWeatherAdapterextendsArrayAdapter<Weather>{Contextcontext;i

我在以下链接中看到了自定义列表视图的程序
http://www.ezzylearning.com/tutorial.aspx?tid=1763429&q=customizing-android-listview-items-with-custom-arrayadapter

这是定制适配器：

public class WeatherAdapter extends ArrayAdapter<Weather>{    Context context;     int layoutResourceID;        Weather data[] = null;    public WeatherAdapter(Context context, int layoutResourceID, Weather[] data) {        super(context, layoutResourceID, data);        this.layoutResourceID = layoutResourceID;        this.context = context;        this.data = data;    }    @OverrIDe    public VIEw getVIEw(int position, VIEw convertVIEw, VIEwGroup parent) {        VIEw row = convertVIEw;        WeatherHolder holder = null;        if(row == null)        {            LayoutInflater inflater = ((Activity)context).getLayoutInflater();            row = inflater.inflate(layoutResourceID, parent, false);            holder = new WeatherHolder();            holder.imgIcon = (ImageVIEw)row.findVIEwByID(R.ID.imgIcon);            holder.txtTitle = (TextVIEw)row.findVIEwByID(R.ID.txtTitle);            row.setTag(holder);        }        else        {            holder = (WeatherHolder)row.getTag();        }        Weather weather = data[position];        holder.txtTitle.setText(weather.Title);        holder.imgIcon.setimageResource(weather.icon);        return row;    }    static class WeatherHolder    {        ImageVIEw imgIcon;        TextVIEw txtTitle;    }}

在getVIEw()方法中,他为WeatherHolder创建了这个WeatherHolder类的对象是什么？

>它是如何创建的？
>它是由我们手动创建的吗？

Because I cant find the body of the “WeatherHolder” class any where
else in the program.

我希望我的问题很明确.程序中的WeatherHolder是什么,谁创建了WatchHolder类.

解决方法:

在ListVIEw的滚动期间,findVIEwByID()(布局的子项为列表视图的行膨胀)经常被调用,这会降低性能.即使适配器返回一个膨胀的视图以进行回收,您仍然需要查找元素并更新它们.重复使用findVIEwByID()的方法是使用视图持有者设计模式.

VIEwHolder对象将每个组件视图存储在Layout的标记字段中,因此您可以立即访问它们而无需重复查找它们.首先,您需要创建一个类来保存您的确切视图集.

这是代码中的类

static class WeatherHolder {        ImageVIEw imgIcon;        TextVIEw txtTitle;}

Yes it is manually created by us
in getVIEw() u will create Object of that class and access it

 @OverrIDe    public VIEw getVIEw(int position, VIEw convertVIEw, VIEwGroup parent) {        VIEw row = convertVIEw;        WeatherHolder holder = null;        if(row == null)        {            LayoutInflater inflater = ((Activity)context).getLayoutInflater();            row = inflater.inflate(layoutResourceID, parent, false);            holder = new WeatherHolder();            holder.imgIcon = (ImageVIEw)row.findVIEwByID(R.ID.imgIcon);            holder.txtTitle = (TextVIEw)row.findVIEwByID(R.ID.txtTitle);            row.setTag(holder);        }        else        {            holder = (WeatherHolder)row.getTag();        }//do ur staffreturn row;}

欲了解更多信息Visit here

http://developer.android.com/training/improving-layouts/smooth-scrolling.html

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