Android记录14--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;
	}

}

// 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);