JAVA8 - 使用stream api进行list集合指定字段去重

水深无声 2022-05-19 03:20 227阅读 0赞

## 背景 ##

有一个list,实体包含多个字段,当其中两个字段值均相同时,就认为list中的这两条记录是一样的

## 去重 ##

java8中有一个collectingAndThen可以根据多个字段去重

依据姓名和年龄去重,当姓名和年龄相同时,认为这两个实体相同

class FlightTicketInfo {
    
        private String orderNumber;
    
        private String userName;
    
        private String age;
    
        public FlightTicketInfo(String orderNumber, String userName, String age) {
            this.orderNumber = orderNumber;
            this.userName = userName;
            this.age = age;
        }
    
        @Override
        public String toString() {
            return "FlightTicketInfo{" +
                    "orderNumber='" + orderNumber + '\'' +
                    ", userName='" + userName + '\'' +
                    ", age='" + age + '\'' +
                    '}';
        }
    
        public String getOrderNumber() {
            return orderNumber;
        }
    
        public String getUserName() {
            return userName;
        }
    
        public String getAge() {
            return age;
        }
    }
    
        @Test
        public void testList(){
            List<FlightTicketInfo> infoList = new ArrayList<>();
            infoList.add(new FlightTicketInfo("11111", "xiaoming", "22"));
            infoList.add(new FlightTicketInfo("22222", "xiaoming", "22"));
            infoList.add(new FlightTicketInfo("33333", "xiaoming", "23"));
            infoList.add(new FlightTicketInfo("11111", "xiaoming", "22"));
            infoList.stream()
                    .collect(Collectors.collectingAndThen(Collectors.toCollection(() -> new TreeSet<>(Comparator.comparing(f -> f.getUserName()+f.getAge()))), ArrayList::new))
                    .forEach(System.out::println);
        }