Android自定义Comparator,实现List按时间排序

 package com.suntek.mobilemeeting.comparator;

 import java.util.Comparator;

 import com.suntek.mobilemeeting.model.User;

 /**
  * 根据用户离线时间定制的比较器
  *
  * @author by wwj
  *
  */
 public class OfflineUserComparator implements Comparator {

     @Override
     public int compare(Object obj1, Object obj2) {
         User user1 = (User) obj1;
         User user2 = (User) obj2;
         int flag = user2.getLeftTime().compareTo(user1.getLeftTime());
         return flag;
     }

 }

这样使用：

 // 离线
                     JSONArray offlineArray = json
                             .optJSONArray(StringUtil.RES_OFF_USER_INFO);
                     offlineUsers.clear();
                     for (int i = 0; offlineArray != null
                             && i < offlineArray.length(); i++) {
                         JSONObject temp = (JSONObject) offlineArray.get(i);
                         User user = new User();
                         user.setUserId(temp.optString(StringUtil.USER_USERID));
                         user.setSerialNo(temp
                                 .optString(StringUtil.USER_SERIAL_NO));
                         user.setUserName(temp.optString(StringUtil.USER_NAME));
                         user.setTelephone(temp
                                 .optString(StringUtil.USER_TELEPHONE));
                         user.setStatus(-1);
                         user.setJoinDateTime(temp
                                 .optString(StringUtil.USER_JOIN_DATE_TIME));
                         user.setLeftTime(temp
                                 .optString(StringUtil.USER_LEFT_TIME));
                         user.setGroupNo(temp.optInt(StringUtil.USER_GROUP_NO));
                         user.setSubConfName(temp
                                 .optString(StringUtil.USER_SUB_CONF_NAME));
                         offlineUsers.add(user);
                     }
                     OfflineUserComparator offlineUserComparator = new OfflineUserComparator();

                     Collections.sort(offlineUsers, offlineUserComparator);