List集合中的对象按照某个字段去重实现

package com.liying.banana.user;

import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;
import java.util.Set;
import java.util.TreeSet;

import com.liying.banana.order.vo.OrderVO;

/**
* List集合中的对象按照某个字段去重实现
*
* @author jqlin
*
*/
public class DuplicateOrderTest {
public static void main(String[] args) {
List<OrderVO> orderList = new ArrayList<OrderVO>();
OrderVO orderVO = new OrderVO();
orderVO.setOrderNo("11");
orderVO.setUserId("aa");
orderList.add(orderVO);

orderVO = new OrderVO();
orderVO.setOrderNo("22");
orderVO.setUserId("bb");
orderList.add(orderVO);

orderVO = new OrderVO();
orderVO.setOrderNo("33");
orderVO.setUserId("aa");
orderList.add(orderVO);

List<OrderVO> dataList = removeDuplicateOrder(orderList);
for(OrderVO data : dataList){
System.out.println(data.getOrderNo() + ":" + data.getUserId());
}
}

/**
* 去重
*
* @param orderList
* @return
* @author jqlin
*/
private static List<OrderVO> removeDuplicateOrder(List<OrderVO> orderList) {
Set<OrderVO> set = new TreeSet<OrderVO>(new Comparator<OrderVO>() {
@Override
public int compare(OrderVO a, OrderVO b) {
// 字符串则按照asicc码升序排列
return a.getUserId().compareTo(b.getUserId());
}
});

set.addAll(orderList);
return new ArrayList<OrderVO>(set);
}
}

11:aa
22:bb