Comparator比较器

一、代码解析

    default Comparator<T> thenComparing(Comparator<? super T> other) {
        Objects.requireNonNull(other);
        return (Comparator<T> & Serializable) (c1, c2) -> {
            int res = compare(c1, c2);
            return (res != 0) ? res : other.compare(c1, c2);
        };
    }

  	List<Employee> employeeList = Arrays.asList(
			new Employee("赵1", 12,85),
			new Employee("赵2", 13,102),
			new Employee("赵3", 11,90),
			new Employee("赵4", 13,90)
			//new Employee("赵4", 15),
			//new Employee("赵5", 10),
			//new Employee("赵5", 10)
    );

自定义排序

   Comparator<Integer> keyComparator = new Comparator<Integer>() {
          @Override
          public int compare(Integer o1, Integer o2) {
              return 0;
          }
    };

    List<Employee> collect = employeeList.stream()
            .sorted(Comparator.comparing(Employee::getAge,Comparator.reverseOrder()) // 使用ReverseComparator的compare(x,y)进行比较
            .thenComparing(Employee::getSroce, keyComparator))                       // 优先比较x与y的Age字段是否相等，若相等则，调用keyComparator自定义比较器，比较sroce字段
            .collect(Collectors.toList());
    System.out.println("---collect---"+JSONObject.toJSON(collect));