ContactAdapter.java

package com.diandi.demo.adapter;

import android.annotation.SuppressLint;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.SectionIndexer;
import android.widget.TextView;

import com.diandi.demo.R;
import com.diandi.demo.model.User;
import com.diandi.demo.util.ImageLoadOptions;
import com.nostra13.universalimageloader.core.ImageLoader;

import java.util.List;

/**
 * *******************************************************************************
 * *********    Author : klob(kloblic@gmail.com) .
 * *********    Date : 2014-11-29  .
 * *********    Time : 11:46 .
 * *********    Project name : Diandi1.18 .
 * *********    Version : 1.0
 * *********    Copyright @ 2014, klob, All Rights Reserved
 * *******************************************************************************
 */
@SuppressLint("DefaultLocale")
public class ContactAdapter extends BaseAdapter implements SectionIndexer {
    private Context ct;
    private List<User> data;

    public ContactAdapter(Context ct, List<User> datas) {
        this.ct = ct;
        this.data = datas;
    }

    /**
     * 当ListView数据发生变化时,调用此方法来更新ListView
     *
     * @param @param list
     * @return void
     * @throws
     * @Title: updateListView
     * @Description: TODO
     */
    public void updateListView(List<User> list) {
        this.data = list;
        notifyDataSetChanged();
    }

    public void remove(User user) {
        this.data.remove(user);
        notifyDataSetChanged();
    }

    @Override
    public int getCount() {
        return data.size();
    }

    @Override
    public Object getItem(int position) {
        return data.get(position);
    }

    @Override
    public long getItemId(int position) {
        return 0;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder viewHolder = null;
        if (convertView == null) {
            convertView = LayoutInflater.from(ct).inflate(
                    R.layout.item_user_friend, null);
            viewHolder = new ViewHolder();
            viewHolder.alpha = (TextView) convertView.findViewById(R.id.alpha);
            viewHolder.name = (TextView) convertView
                    .findViewById(R.id.tv_friend_name);
            viewHolder.avatar = (ImageView) convertView
                    .findViewById(R.id.img_friend_avatar);
            convertView.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder) convertView.getTag();
        }

        User friend = data.get(position);
        final String name = friend.getNick();
        String avatarUrl = null;
        if (friend.getAvatar() != null) {
            avatarUrl = friend.getAvatar();
        }
        ImageLoader.getInstance().displayImage(avatarUrl, viewHolder.avatar,
                ImageLoadOptions.getOptions());
        viewHolder.name.setText(name);

        // 根据position获取分类的首字母的Char ascii值
        int section = getSectionForPosition(position);
        // 如果当前位置等于该分类首字母的Char的位置 ，则认为是第一次出现
        if (position == getPositionForSection(section)) {
            viewHolder.alpha.setVisibility(View.VISIBLE);
            viewHolder.alpha.setText(friend.getSortLetters());
        } else {
            viewHolder.alpha.setVisibility(View.GONE);
        }

        return convertView;
    }

    /**
     * 根据ListView的当前位置获取分类的首字母的Char ascii值
     */
    public int getSectionForPosition(int position) {
        return data.get(position).getSortLetters().charAt(0);
    }

    /**
     * 根据分类的首字母的Char ascii值获取其第一次出现该首字母的位置
     */
    @SuppressLint("DefaultLocale")
    public int getPositionForSection(int section) {
        for (int i = 0; i < getCount(); i++) {
            String sortStr = data.get(i).getSortLetters();
            char firstChar = sortStr.toUpperCase().charAt(0);
            if (firstChar == section) {
                return i;
            }
        }

        return -1;
    }

    @Override
    public Object[] getSections() {
        return null;
    }

    static class ViewHolder {
        TextView alpha;// 首字母提示
        ImageView avatar;
        TextView name;
    }

}