场景：

　　List里面的对象是订单的节点，比如我们快递的物流状态，这个是需要有序的，所以需要根据订单号进行分组排序。

 

import java.util.ArrayList;import java.util.Collections;import java.util.Comparator;import java.util.HashMap;import java.util.List;import java.util.Map;public class GroupSortTest {    public static void main(String[] args) {            List
     
       list = new ArrayList
      
       ();        Order o1 = new Order("10086","3",(long) 1008603);        Order o2 = new Order("10086","2",(long) 1008602);        Order o3 = new Order("10086","1",(long) 1008601);        Order o4 = new Order("10010","1",(long) 1001001);        Order o5 = new Order("10000","3",(long) 1000003);        Order o6 = new Order("10010","3",(long) 1001003);        Order o7 = new Order("10000","1",(long) 1000001);        Order o8 = new Order("10000","2",(long) 1000002);        Order o9 = new Order("10010","2",(long) 1001002);                list.add(o1);        list.add(o2);        list.add(o3);        list.add(o4);        list.add(o5);        list.add(o6);        list.add(o7);        list.add(o8);        list.add(o9);                Map
       
        > map = OrderSortByGroup(list);                for(Map.Entry
        
         > entry : map.entrySet()){            for(Order o : entry.getValue() ){                System.out.println(entry.getKey() +"--"+o.getSeq()+"--"+o.getStatusId());            }        }            }        public static Map
         
          > OrderSortByGroup(List
          
            list){ Map
           
            > map = new HashMap
            
             >(); for(Order order : list) { List
             
               staList = map.get(order.orderNo); if(staList==null){ staList = new ArrayList
              
               (); } Order od = new Order(); od.setSeq(order.seq);od.setStatusId(order.statusId); staList.add(od); Collections.sort(staList, new Comparator
               
                () { @Override public int compare(Order o1, Order o2) { return o1.getSeq().compareTo(o2.getSeq()); } }); map.put(order.orderNo, staList); } return map; } }class Order { String orderNo; //订单号 String seq; //订单节点序号 Long statusId; //订单节点主键 public Order() {} public Order(String orderNo, String seq, Long statusId) { super(); this.orderNo = orderNo; this.seq = seq; this.statusId = statusId; } public String getOrderNo() { return orderNo; } public void setOrderNo(String orderNo) { this.orderNo = orderNo; } public String getSeq() { return seq; } public void setSeq(String seq) { this.seq = seq; } public Long getStatusId() { return statusId; } public void setStatusId(Long statusId) { this.statusId = statusId; }}