Java中如何将对象按属性进行分组呢？

实现思路:
    借助java8中的stream流，可对集合进行分组操作

//集合定义
list<Student> studlist = new ArrayList<>();

        studlist.add(new Student("1", "aa", "China"));
        studlist.add(new Student("2", "bb", "China"));
        studlist.add(new Student("3", "cc", "China"));
        studlist.add(new Student("4", "dd", "New York"));
        studlist.add(new Student("5", "ee", "California"));
        studlist.add(new Student("6", "ff", "New York"));

//group by
Map<String, List<Student>> list =
    studlist.stream().collect(Collectors.groupingBy(w -> w.stud_location));