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优化SimpleAdapter适配器加载效率的方法

程序员文章站 2022-05-30 18:24:51
在主activity中: listview=(listview)findviewbyid(r.id.listview);getdata(); //为list...

在主activity中:

listview=(listview)findviewbyid(r.id.listview);getdata();

//为list添加数据overridesimpleadapter=new overridesimpleadapter(getcontext(),list,r.layout.list_item_layout,       

new string[]{"num","word","translates"},       

new int[]{r.id.tv_num,r.id.tv_word,r.id.tv_translates});

listview.setadapter(overridesimpleadapter);

重写simpleadapter:/**
 * created by kewenc on 2017/1/26.
 */

public class overridesimpleadapter extends simpleadapter {
  /**
   * constructor
   *
   * @param context the context where the view associated with this simpleadapter is running
   * @param data   a list of maps. each entry in the list corresponds to one row in the list. the
   *         maps contain the data for each row, and should include all the entries specified in
   *         "from"
   * @param resource resource identifier of a view layout that defines the views for this list
   *         item. the layout file should include at least those named views defined in "to"
   * @param from   a list of column names that will be added to the map associated with each
   *         item.
   * @param to    the views that should display column in the "from" parameter. these should all be
   *         textviews. the first n views in this list are given the values of the first n columns
   */

  private layoutinflater minflater;
  private arraylist<map<string, object>> list;
  private int mresource;
  private int[] mto;
  private string[] mfrom;

  public overridesimpleadapter(context context, arraylist<map<string, object>> data, int resource, string[] from, int[] to) {
    super(context, data, resource, from, to);
    this.list=data;
    this.minflater = layoutinflater.from(context);
    this.mresource = resource;
    this.mfrom = from;
    this.mto = to;
  }

  @override
  public int getcount() {
    return list.size();
  }

  @override
  public object getitem(int position) {
    return list.get(position);
  }

  @override
  public long getitemid(int position) {
    return position;
  }

  @override
  public view getview(int position, view convertview, viewgroup parent) {
    viewholder holder = null;
    // 判断是否缓存
    if (convertview == null) {
      holder = new viewholder();
      // 通过layoutinflater实例化布局
      convertview = minflater.inflate(mresource, null);
//      holder.img = (imageview) convertview.findviewbyid(r.id.imageview);
      holder.num = (textview) convertview.findviewbyid(mto[0]);
      holder.word = (textview) convertview.findviewbyid(mto[1]);
      holder.translates = (textview) convertview.findviewbyid(mto[2]);
      convertview.settag(holder);
    } else {
      // 通过tag找到缓存的布局
      holder = (viewholder) convertview.gettag();
    }
    // 设置布局中控件要显示的视图
//    holder.img.setbackgroundresource(r.drawable.ic_launcher);
    holder.num.settext(list.get(position).get(mfrom[0]).tostring());// mfrom[0]为“num”key
    holder.word.settext(list.get(position).get(mfrom[1]).tostring());
    holder.translates.settext(list.get(position).get(mfrom[2]).tostring());
    return convertview;
  }

  public final class viewholder {
//    public imageview img;
    public textview num;
    public textview word;
    public textview translates;
  }
}

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