自定义ArrayAdapter深入

如果数据来源是Json的情况下：

  //从json对象中获得user对象    public User(JSONObject object) {        try {            this.name = object.getString("name");            this.hometown = object.getString("hometown");        } catch (JSONException e) {            e.printStackTrace();        }    }    //将一组user对象存储在数组列表中，首先要获得Json数组    public static ArrayList<User> fromJson(JSONArray jsonObjects) {        ArrayList<User> users = new ArrayList<User>();        for (int i = 0; i < jsonObjects.length(); i++) {            try {                users.add(new User(jsonObjects.getJSONObject(i)));            } catch (JSONException e) {                e.printStackTrace();            }        }        return users;    }}

优化ListView

public class UserAdapter extends ArrayAdapter<User> {    //使用viewHolder缓存数据    private static class ViewHolder {        TextView name;        TextView home;    }    @Override    public View getView(int position , View convertView, ViewGroup parent) {    //获得相应位置的类        User user = getItem(position);        ViewHolder viewHolder;        if (convertView == null) {            viewHolder = new ViewHolder();            convertView = LayoutInflater.from(getContext()).inflate(R.layout.item_user, parent, false);            //加载两个textView视图            viewHolder.name = (TextView) convertView.findViewById(R.id.tvName);            viewHolder.home = (TextView) convertView.findViewById(R.id.tvHome);            //将viewHolder存贮在convertView中            convertView.setTag(viewHolder);        } else {        //将convertView中存储的数据还原成viewHolder            viewHolder = (viewHolder) convertView.getTag();        }        viewHolder.name.setText(user.name);        viewHolder.home.setText(user.hometown);        return convertView;    }}