List对象分组排序算法

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<Order> list = new ArrayList<Order>();
        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<String, List<Order>> map = OrderSortByGroup(list);

        for(Map.Entry<String, List<Order>> entry : map.entrySet()){
            for(Order o : entry.getValue() ){
                System.out.println(entry.getKey() +"--"+o.getSeq()+"--"+o.getStatusId());
            }
        }

    }

    public static Map<String, List<Order>> OrderSortByGroup(List<Order> list){
        Map<String, List<Order>> map = new HashMap<String, List<Order>>();
        for(Order order : list) {
            List<Order> staList = map.get(order.orderNo);
            if(staList==null){
                staList = new ArrayList<Order>();
            }
            Order od = new Order();
            od.setSeq(order.seq);od.setStatusId(order.statusId);
            staList.add(od);

            Collections.sort(staList, new Comparator<Order>() {
                @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;
    }
}

输出结果:

10086--1--1008601
10086--2--1008602
10086--3--1008603
10000--1--1000001
10000--2--1000002
10000--3--1000003
10010--1--1001001
10010--2--1001002
10010--3--1001003

转载自:https://www.cnblogs.com/jager/p/6072987.html