Android中BaseAdapter用法示例

本文实例讲述了android中baseadapter用法。分享给大家供大家参考，具体如下：

概述：

baseadapter就android应用程序中经常用到的基础数据适配器，它的主要用途是将一组数据传到像listview、spinner、gallery及gridview等ui显示组件，它是继承自接口类adapter

baseadapter

java代码：

public class recentadapter extends baseadapter {
  private class recentviewholder {
    textview appname;
    imageview appicon;
    textview appsize;
  }
  private list<resolveinfo> mapplist;
  private layoutinflater minflater;
  private packagemanager pm;
  public recentadapter(context c, list<resolveinfo> applist,
      packagemanager pm) {
    mapplist = applist;
    this.pm = pm;
    minflater = (layoutinflater) c
        .getsystemservice(context.layout_inflater_service);
  }
  public void clear(){
    if(mapplist!=null){
      mapplist.clear();
    }
  }
  public int getcount() {
    return mapplist.size();
  }
  @override
  public object getitem(int position) {
    return mapplist.get(position);
  }
  @override
  public long getitemid(int position) {
    // todo auto-generated method stub
    return position;
  }
  public view getview(int position, view convertview, viewgroup parent) {
    recentviewholder holder;
    if (convertview == null) {
      convertview = minflater.inflate(r.layout.app_info_item, null);
      holder = new recentviewholder();
      holder.appname = (textview) convertview.findviewbyid(r.id.app_name);
      holder.appicon = (imageview) convertview
          .findviewbyid(r.id.app_icon);
      holder.appsize = (textview) convertview.findviewbyid(r.id.app_size);
      convertview.settag(holder);
    } else {
      holder = (recentviewholder) convertview.gettag();
    }
    resolveinfo appinfo = mapplist.get(position);
    if (appinfo != null) {
      string labelname = appinfo.loadlabel(pm).tostring();
      if (labelname != null) {
        holder.appname.settext(labelname);
      }
      drawable icon = appinfo.loadicon(pm);
      if (icon != null) {
        holder.appicon.setimagedrawable(icon);
      }
    }
    return convertview;
  }
  public void remove(int position){
    mapplist.remove(position);
    this.notifydatasetchanged();
  }
}

其中两个注意点为：

settag 用view设置存储数据

notifydatasetchanged() 告诉view数据更改并刷新

view convertview = minflater.inflate(r.layout.app_info_item, null)  加载xml item 视图

app_info_item.xml文件示例：

xml代码：

<?xml version="1.0" encoding="utf-8"?>
<relativelayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent" android:layout_height="wrap_content"
  android:layout_gravity="center_vertical" android:minheight="?android:attr/listpreferreditemheight">
  <imageview android:id="@+id/app_icon" android:layout_width="@android:dimen/app_icon_size"
    android:layout_height="@android:dimen/app_icon_size"
    android:layout_alignparentleft="true" android:paddingleft="6dip"
    android:paddingtop="6dip" android:paddingbottom="6dip"
    android:scaletype="fitcenter" />
  <textview android:id="@+id/app_name" android:layout_width="wrap_content"
    android:layout_height="wrap_content" android:textappearance="?android:attr/textappearancelarge"
    android:textcolor="?android:attr/textcolorprimary"
    android:layout_torightof="@id/app_icon" android:paddingleft="6dip"
    android:paddingtop="6dip" />
  <textview android:id="@+id/app_description"
    android:layout_width="wrap_content" android:layout_height="wrap_content"
    android:textappearance="?android:attr/textappearancesmall"
    android:layout_below="@+id/app_name" android:layout_torightof="@id/app_icon"
    android:paddingleft="6dip" android:paddingbottom="6dip" />
  <textview android:id="@+id/app_size" android:layout_width="wrap_content"
    android:layout_height="wrap_content" android:textappearance="?android:attr/textappearancesmall"
    android:layout_alignparentright="true" android:layout_below="@+id/app_name"
    android:paddingright="6dip" android:maxlines="1" />
</relativelayout>

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希望本文所述对大家android程序设计有所帮助。