How to sort an attribute of an object using Collections

Question

Good day!

I have an object student with the following attributes:

class Student
    String name
    Date birthday

I used arrayList

Answer 1

You can pass a Comparator to Collections.sort() to handle the sorting by birthday:

Collections.sort(studentList, new Comparator() {
    public int compare(Student s1, Student s2) {
        return s1.getBirthday().compareTo(s2.getBirthday());
    }
});

You'll need to add getBirthday() to your Student class if you don't have it already.